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Causes of mortality at nests of ground-nesting birds in the Upper Waitaki Basin, South Island, New Zealand: A 5-year video study
Abstract
We used video cameras over 5 years to quantify causes of mortality at 172 nests of three species of ground-nesting birds that nest on braided riverbeds of the Upper Waitaki Basin, South Island, New Zealand. The species were banded dotterels Charadrius bicinctus (n=114), black stilts Himantopus novaezelandiae (n=23), and black-fronted terns Sterna albostriata (n=35). Of 77 recorded lethal events (excluding four desertions caused by us), 66 involved deaths of only eggs, and 11 involved deaths of adults and/or chicks, and/or eggs. The main predators were cats Felis catus, hedgehogs Erinaceus europaeus, and ferrets Mustela furo, which were responsible for 43, 20, and 18% of lethal events, respectively. Cats were the only predator species to take adult birds. We recorded only two avian predations: a harrier Circus approximans took a chick and a hatching egg from one nest, and an Australian magpie Gymnorhina tibicen ate chicks at one nest. Other causes of mortality were incubating adult birds, floods, and sheep Ovis aries. Each accounted for <4% of lethal events. Ninety percent of visits (151 of 168) by predators or potential predators happened between sunset and sunrise. We found no evidence that video cameras or infra-red lighting influenced predation rates during 2 years of testing for such effects.
... Globally, introduced mammalian predators are implicated in the decline of biodiversity (Blackburn et al. 2004;Doherty et al. 2016). In New Zealand, feral cats (Felis catus), stoats (Mustela erminea), weasels (Mustela nivalis), ferrets (Mustela furo), brushtail possums (Trichosurus vulpecula), and European hedgehogs (Erinaceus europaeus) are all predators of native avifauna, negatively affecting their populations (Moors 1983;Sanders & Maloney 2002;Moorhouse et al. 2003;Jones & Norbury 2006). As a result, significant effort is invested into the control of these introduced predators using a variety of methods (Baber et al. 2009;O'Donnell & Hoare 2012;Fea et al. 2021). ...
... Mustelids (stoats, ferrets, weasels) and cats (domestic and feral) are suspected predators of mallard nests and incubating hens in the Southland agricultural landscape (Sheppard 2017;Sheppard et al. 2019;Stewart et al. 2019;Southland Fish and Game unpubl. data); however, hedgehogs and possums may also prey on mallard nests as they are known to consume bird eggs (Brown et al. 1993;McDonald et al. 2000;Sanders & Maloney 2002). Swamp harriers (Circus approximans) and pukeko (Porphyrio melanotus) are native predators of avian nests (Boulton & Cassey 2006;Kross et al. 2013;Innes et al. 2015) and have been observed preying on mallard nests (Morgan et al. 2006;CS pers. ...
... Therefore, farm-scale control of mammalian predators will likely have little effect on mallard nest predation rates. Limited predation of the nests by cats, stoats, and ferrets was unexpected because these predators are known to consume bird eggs in both real (Sanders & Maloney 2002;Stewart et al. 2019) and artificial nests (Smith et al. 2008;Kross et al. 2013). The reason for limited nest predation may be related to the availability of alternative prey. ...
Artificial mallard (Anas platyrhynchos) nests were used to identify potential nest predators and assess whether small, farm-scale predator control could reduce mallard nest predation in Southland, New Zealand. Artificial nests were deployed over the mallard nesting period (late winter – spring) in both 2019 and 2020 and monitored with motion detection cameras. Prior to 2020 artificial nest deployment, farm-scale trapping of mammalian predators was conducted on one farm whilst the other was left as a control. Feral cats (Felis catus), brushtail possums (Trichosurus vulpecula), and European hedgehogs (Erinaceus europaeus) frequently visited the artificial nests but seldom preyed on them (i.e. consumed the eggs). Swamp harrier (Circus approximans) were the most common predator and were responsible for the destruction or predation of at least one egg at 17% of the artificial nests. Mammalian predator trapping had no noticeable effect on artificial nest predation, but did reduce the probability an artificial nest was visited by a cat, possum, or hedgehog. Results suggest typical predator control efforts of gamebird hunters does not reduce mallard nest predation, but may reduce nest disturbance and consequently mallard hen predation and nest abandonment.
... Thus, it is timely to review current population trends of banded dotterels. Braided river species including banded dotterels are threatened by a combination of factors on their breeding grounds, particularly predation by introduced mammalian predators and native avian predators (Rebergen et al. 1998;Sanders & Maloney 2002;Steffens et al. 2012;Schlesselmann et al. 2018), weed invasion, water and gravel abstraction, and dams, resulting in significant habitat loss. In addition, flood protection and other river control works are changing habitat characteristics, and disturbance from human recreational activities on rivers such as jetboating, four-wheel driving and fishing threaten nest and chick survival . ...
... Although there are generally low numbers of rats (Rattus spp.) on braided rivers, predation by invasive mammalian predators is still the most obvious direct threat, with high levels of nest loss (>50%) particularly attributed to cats (Felis catus), stoats (Mustela erminea), ferrets (M. furo), and hedgehogs (Erinaceus europaeus) (Bomford 1988;Rebergen et al. 1998;Keedwell 2002;Sanders & Maloney 2002;Norbury & Heyward 2007). Predator control, to increase productivity and survival of braided river birds, has been trialled using a range of standard trapping techniques on several rivers at a range of spatial and temporal scales . ...
... The occurrence of continued declines is not surprising given the large number of anthropogenic threats faced by banded dotterels, particularly on their breeding grounds , and the consistently high predation rates by introduced mammals recorded in all studies undertaken to date (particularly from cats, mustelids, and hedgehogs ;Hughey 1985a;Bomford 1988;Rebergen et al. 1998;Keedwell 2002;Sanders & Maloney 2002;McEntee 2007;Norbury & Heyward 2007). ...
Banded dotterels (tūturiwhatu, Charadrius bicinctus bicinctus) are small plovers inhabiting New Zealand's braided rivers, estuaries, seashores, and open country. They are considered Nationally Vulnerable under national threat listing criteria, but with uncertainty around the trend estimation. We collated and reviewed counts of banded dotterels on their braided river breeding grounds from throughout the country, 1962-2017, to describe their distribution, assess population trends, estimate rates of population change, and assess the appropriateness of the threat status given to this species. We also used nationwide winter count data for banded dotterels from 1984 to 2018 as an independent measure to compare trends. Banded dotterel counts were recorded for 119 braided and shingle river reaches, mostly in the South Island (87%) with far fewer rivers in the North Island (13%). The sum of banded dotterel counts was 12,730 birds when tallying the most recent counts/river. Although they were most widespread in the South Island, particularly Canterbury, the majority (>50%) of dotterels counted on the most recent surveys were from just 10 (8%) rivers with the largest single concentrations on three Hawkes Bay rivers. Counts suitable for long-term trend analysis were only available for South Island sites. Widespread declines in banded dotterel count indices were recorded. The weighted mean annual rate of change across 33 South Island rivers was-3.7% p.a. (per annum), which equates to a 52.3% decline over 20 years (~3 generations). We also detected a negative trend in dotterel numbers based on national winter count data, but of a smaller magnitude (-1.4% p.a., equating to a 25% decline over 20 years). However, trends in Australia, where c. 60% of banded dotterels over-winter, are unknown. In contrast, a significant population increase was measured on the Hakatere Reach of the South Ashburton River, which has intensive, sustained predator control, and several predator trapping initiatives on other braided rivers and coastal areas indicate declines can be reversed with management if applied at an extensive landscape scale. Banded dotterels are subject to a wide range of threats including very high levels of predation by invasive predators, human disturbance on breeding grounds, and habitat loss and degradation. Using the precautionary principle, the rates of decline on South Island braided rivers confirm the classification of Nationally Vulnerable using the NZ Threat Classification system. However, results suggest that the IUCN threat status for banded dotterel should be reclassified from Least Concern to Endangered. O'Donnell, C.F.J.; Monks, J.M. 2020. Distribution, long term population trends and conservation status of banded dotterels (Charadrius bicinctus bicinctus) on braided rivers in New Zealand. Notornis 67(4): 733-753.
... ' Accidental' egg removal (e.g. when the egg adheres to the abdominal feathers) can be distinguished from nest relocation because the egg is either left unattended or returned to the original nest scrape (Sanders & Maloney 2002, White et al. 2009). ...
... Alternatively, the parent may have been moving the egg away from the recently installed camera. Sanders & Maloney (2002) videoed a Doublebanded Dotterel which "dropped an egg when flying from the nest, and later retrieved the egg, which had fallen outside the nest but had not broken". ...
... Such organisms would display staggered life history timings, with bethedging strategies likely a common evolutionary adaptation to the unpredictability of flow events in braided rivers (Lytle and Poff, 2004). Higher-level consumers have evolved adaptations to cope with braided river unpredictability: many braided river bird species have the capacity to lay several clutches in a season to combat flooding events that may occur in a breeding season and destroy nests (Heather et al., 2015;Sanders and Maloney, 2002). Furthermore, in years where river channels are scoured by floods many species of river birds can gain alternate food sources from other areas of the braidplain such as ponds and mudflats, despite preferring lipid-rich prey from main channels (Pierce, 1983). ...
... Weed encroachment can also directly cause terrestrial habitat loss and reduce biodiversity of species that have evolved specific traits to deal with the inherently unstable flow regime. For example, the birds that are top predators on braided rivers in New Zealand no longer have areas to nest and feed in weed-dominated areas, whilst simultaneously becoming more vulnerable to nonnative mammalian predators (Maloney et al., 1999;Sanders and Maloney, 2002). Thus, weed invasions push the whole river system towards a much more homogeneous environment where resilience mechanisms inherently associated with a moving bed habitat mosaic are significantly reduced, and the feedbacks likely lock the braidplain in a new degraded and less resilient state. ...
... Predation is a major cause of breeding failure for some of these species, including black stilts (Himantopus novaezelandiae) (Pierce 1986), banded dotterels (Charadrius bicinctus) (Rebergen et al. 1998), and black-fronted terns (Chlidonias albostriatus) (Keedwell et al. 2002a). The main predators at nests of these species in three Mackenzie Basin rivers were feral cats (Felis catus), ferrets (Mustela furo), and hedgehogs (Erinaceus europaeus) (Sanders & Maloney 2002). In the case of black-fronted terns, Norway rats (Rattus norvegicus) were also implicated in predation of chicks, juveniles, and adults (Keedwell et al. 2002a). ...
... There are obvious reasons why chicks and eggs may show different levels of susceptibility to various threats. First, they may be vulnerable to different predators; for example, hedgehogs prey on many shorebird nests in the Mackenzie Basin (Sanders & Maloney 2002) but are too slow to catch most shorebird chicks, which are precocial and highly mobile. Because they are mobile, chicks may be more susceptible to avian predators, which hunt largely by sight. ...
The wrybill (Anarhynchus frontalis) is an endemic plover that breeds only in braided rivers east of the main divide in the South Island of New Zealand. It is threatened by a range of factors, including loss and degradation of habitat, flooding, and predation. We monitored wrybills in 2 sites in the Tekapo River and 2 in the Tasman River in the Mackenzie Basin, South Canterbury, during 3 breeding seasons (1997/98-1999/2000). We aimed to compare survival and productivity between areas with and without trapping (mammalian predator control) to determine whether predator control was associated with higher survival and/or breeding success of wrybills. In the Tekapo River, results were similar between trapped and un-trapped areas, suggesting that control had little effect. In the Tasman River, there were large differences between the two sites and trapping appeared to be beneficial; in the upper river (un-trapped), productivity and survival were very low and in the lower (trapped) site they were high. Over the whole study, 67.3% of nests hatched, and depredation was the largest cause of nest failure. Fledging success (the proportion of chicks hatched that fledged) averaged 35.4%. Losses at the chick stage were higher than at the egg stage, and there was only a weak correlation between nesting success and overall breeding success; we therefore caution against the use of nesting success as a proxy for overall breeding success. Productivity averaged 0.49 chicks fledged per pair over the whole study; when the very low values from the upper Tasman site were excluded, productivity averaged 0.61. Survival of adult male wrybills was lower than survival of females in all four study sites. Measurement of adult survival is important in determining the full effect of predator control (and in determining population trends) but is often overlooked. At the time of our study, wrybill populations in 3 of our 4 study sites appeared not to be self-sustaining and, in the absence of immigration, were in decline. A number of factors, including depredation by mammals, can affect breeding success. Trapping may be beneficial, but temporal and geographic differences in predator densities, as well as variability in other threats (such as flooding and levels of avian predation) mean that predicting when and where mammalian predator control may benefit wrybills is currently difficult. Dowding, J.E.; Murphy, E.C.; Elliott, M.J. 2020. Survival and breeding success of wrybills (Anarhynchus frontalis) in the Tekapo and Tasman Rivers, South Canterbury, New Zealand. Notornis 67(4): 755-764.
... Key threats to species survival include predation, and habitat loss and modification (Maloney & Murray, 2001). Introduced predators include feral cats (Felis catus), hedgehogs (Erinaceus europaeus), stoats (Mustela erminea) and ferrets (Mustela furo), with disproportionate impacts on chicks and juveniles (Pierce, 1986b;Sanders & Maloney, 2002). Since 1850, 40% of Te Manahuna wetlands have been drained (Wilson, 2001), with similar land conversion across the country. ...
... Egg-pulling encourages pairs to produce multiple clutches, increasing the number of eggs produced beyond the potential of the wild population (Heezik et al., 2005). High rates of predation in the wild are the main driver of low survival to adulthood (Keedwell et al., 2002;Maloney & Murray, 2001;Pierce, 1986bPierce, , 1996Sanders & Maloney, 2002) and so chicks are reared in captivity. Juveniles reaching the age of independence are released back into the wild to supplement subpopulations (Maloney & Murray, 2001). ...
Interspecific hybridisation—the breeding between distinct species—can contribute to species extinction due to wasted reproductive potential, outbreeding depression, and introgression of genetic material mediated by backcrossing. Incomplete reproductive barriers can facilitate interspecific hybridisation as previously isolated species come into contact with one another. Interspecific hybridisation is relatively common among birds, but anthropogenic impacts that increase the incidence of such hybridisation between threatened native species and non-threatened species are of conservation concern due to the risks of genetic swamping, which at its most extreme may result in species extinction. While the impacts of interspecific hybridisation have previously been assessed using small numbers of genetic markers, new genomic sequencing developments now facilitate implementation of genome-wide reassessments providing greater resolution of analyses.
The critically endangered kakī (black stilt; Himantopus novaezelandiae) is one such species that can benefit from these new genomic data. Anthropogenic habitat change and introduction of mammalian predators resulted in the decline of this Aotearoa New Zealand endemic wading bird during the 1900s. An intense population bottleneck resulting in an ephemeral sex-bias among the remaining kakī contributed to hybridisation with the self-introduced poaka (the Aotearoa New Zealand population of the Australian pied stilt; H. himantopus leucocephalus), a congeneric species previously thought to have diverged from a common ancestor with kakī one million years ago. Intensive conservation management including captive breeding for translocation and predator control has increased kakī numbers from ~23 adults in 1981 to approximately 169 wild adults in 2020. Previous genetic studies identified minimal evidence of introgression of poaka genetic material into kakī, and determined that moderate outbreeding depression in combination with stochastic processes likely limited introgression. These data informed the kakī captive breeding for translocation programme with the aim of maintaining genetic integrity. However, re-evaluation using genomic data was recommended for kakī.
Using high-throughput sequencing techniques, I sequenced and assembled the first reference genomes for kakī and Australian pied stilts as tools for use in analyses of introgression. The kakī mitochondrial genome was also assembled to facilitate comparisons of contemporary and historic stilt diversity, showing that conservation management aimed at maximising genetic diversity has largely maintained mitochondrial diversity despite kakī decline, identifying three mitochondrial haplotypes present among contemporary kakī. Kakī and poaka are well-differentiated, and are estimated to have diverged from a common ancestor approximately 750,000 years ago based on Bayesian analysis of mitochondrial data. In addition, the analysis of high-resolution genomic markers generated from approximately 65% of contemporary wild kakī detected no introgression from poaka to kakī despite past hybridisation. These findings confirm the results of previous genetic analysis of introgression and the success of past conservation management. As kakī recovery continues, these combined findings will be used by the New Zealand Department of Conservation’s Kakī Recovery Programme to further maintain the genetic integrity of kakī. Overall, the genomic resources developed here have facilitated the transition from using genetic data to genomic data for kakī recovery, and contribute to our understanding of the impacts of anthropogenic hybridisation on a critically endangered taonga species.
... Identification of nest predators and knowledge of their population dynamics are critical to understand the predation pressure on bird populations and for the implementation of conservation measures, particularly for threatened or endemic bird species (Sanders and Maloney 2002;Rader et al. 2007;Richardson et al. 2009). The use of camera traps in the study of avian ecology is becoming increasingly popular (O'Brien and Kinnaird 2008). ...
... The identification of the main nest predators is crucial for the management and conservation of threatened bird populations (Sanders and Maloney 2002;Rader et al. 2007;Richardson et al. 2009). This is particularly relevant on oceanic islands which harbour an important number of vulnerable and endemic species and contribute greatly to the world's biodiversity (Whittaker and Fernández-Palacios 2007). ...
Nest predation is the main cause of reproductive failure in many bird species. Identification of predators is crucial to understand and interpret the factors that affect nest predation. Although nest predation is a natural top-down regulator of bird populations, its effect is usually more dramatic when introduced predators are involved, particularly in oceanic islands. In the Azores archipelago, the endemic Azores Woodpigeon (Columba palumbus azorica) is believed to be under high predation pressure. We used motion-triggered cameras to monitor nests of the Azores Woodpigeon on two islands of the archipelago (Pico and Terceira) in order to identify nest predators, quantify their impact on this bird and better understand the determinants of predation rates. We sampled 56 nests, during 569 camera trap days, obtaining around 125,000 photographic records. Two introduced predators were identified, black rat (on both islands) and feral cat (only on Terceira), both depredating eggs and chicks. Breeding success, calculated using the Mayfield method, was estimated at 19% on Pico and only 9% on Terceira. Overall, predation was the main cause of breeding failure. General linear models showed that predation rates are positively correlated to fruit availability and negatively correlated to elevation, human population density and adult Woodpigeon attendance at the nest. Edge distance, nest height or cover of trees did not affect predation. Camera traps also provided additional and useful information on predator behaviour when approaching a nest and on daily activity patterns of both adult Woodpigeon and nest predators.
... Our meta-analysis results indicated that rodents are more detrimental to the reproductive success of seabirds than cats. Our literature review indicated that, although predation by both cats and rodents are considered major threats to the persistence of seabird colonies, there is a more extensive literature on the negative effects of predation by rodents (Burger and Gochfeld 1994, Sanders and Maloney 2002, Rayner et al. 2007, Hughes et al. 2008, Le Corre 2008, Medina et al. 2011). In addition, only three studies assessed predation by cats and rodents simultaneously (Jones et al. 2003, Le Corre 2008, Nishijima et al. 2014. ...
Seabirds belong to one are the most threatened bird groups in the world. One of the main threats and most relevant risk for local extinction of these birds is the predation by introduced mammals (cats, rats, and mice). Due to the severity of the impact of predators on seabirds, investigation of the effect of predation by cats and rodents (mice and rats) on the reproductive success of seabirds is needed to assess whether the success increases when the predator is managed and for how long. Our objective was to evaluate, through a global systematic literature review and a meta-analysis, the effectiveness of predator control on the reproductive success of seabirds, taking into account the type of predator and the control period. After the review, 85 articles published between 1974 and 2022 were selected, resulting in 14 articles (16 datasets) adequate for the meta-analysis. For comparison among studies, we used the effect size of the predator control in the meta-analysis models, accounting for their sample sizes. We detected that when predators are controlled, seabird reproductive success increases significantly (mean effect size = 1.4, range: 1.19–1.64). This control was significant for mice/rats as predators (mean = 1.61, range: 1.31–1.98, n = 14) but not for cats (mean = 0.60, range: 0.12–2.96, n = 2). Moreover, short-term predator control (<4 years; mean = 1.52; range: 1.25–1.84, n = 11) was more effective than long-term control (≥ 4 years; mean = 1.15, range: 0.52–2.54, n = 5). Thus, the need of these long-term studies must be evaluated on a case-by-case basis, also considering their increased costs. We also highlight the need for further studies with quantitative data on the percentage of nests with reproductive success, both in the absence and in the presence of the predator control.
... Waterbird populations have been experiencing declining trends all over the world, due to various anthropogenic threats like habitat loss and alteration, disturbance, hunting, climate change, along with reproductive failure and invasion of domestic and feral animals (BirdLife International 2017, Ramachandran et al. 2017, Keller et al. 2020, Datta 2022, Marshall et al. 2022). Due to their specialized breeding ecology and habitat requirements, ground nesting waterbirds, such as plovers, lapwings, terns, thickknees, and pratincoles are highly vulnerable to animal predation, habitat loss, hydrologic fluctuations, and disturbance from humans and domestic animals (Sanders & Maloney 2002, Chace & Walsh 2006. Understanding local ecological and environmental changes of waterbird habitats can fill the knowledge gaps regarding understudied species and provide crucial information for their conservation. ...
The nesting ecology of two wetland-dependent bird species, the Little Tern (Sternula albifrons) and the Small Pratincole (Glareola lactea) were studied in two seasonally emerged riverine islands, locally named as charlands in Padma River of Bangladesh. A total of 269 and 299 nests of Little Tern and Small Pratincole were found in the breeding season of 2022. We monitored 70 nests of the two species from two charlands, and the nesting success was 74.28% and 78.57%, respectively. No correlation was found between nesting success of both species in relation to clutch size, nest height, nest depth and presence of vegetation near nest. We found strong positive correlation between nesting success and nest distance to river for Little Tern. Nesting success was higher if the Little Tern’s nests were located far from the river channel. However, no such trends were observed for Small Pratincole in the study area. The main factor affecting Little Tern nesting success was nest predation by avian predator (n = 6) and tropical storms (n = 3). On the contrary, eight Small Pratincole nests were predated by avian predators and four nests were lost due to storm. However, in case of 12 deserted nests (with unhatched eggs) of both species, no apparent reasons were identified. The study suggests that these charlands, if protected from human interferences, can provide great breeding support for colonial ground nesting waterbirds.
... No information was available at all regarding adult survival of black-billed gulls or banded dotterels (Fig. 3). There is now considerable evidence that predation by introduced mammals and native avian predators is an important threat to nest, chick, and (in some instances) adult survival in these species at breeding grounds (Hay 1984; Rebergen et al. 1998;Sanders & Maloney 2002;Keedwell 2005;Norbury & Heyward 2008;Steffens et al. 2012;Cruz et al. 2013;Schlesselmann et al. 2018). However, individuals in these bird populations can spend as much as 70% of the year away from the breeding grounds (Appendix S1), and face a range of other, seasonally specific threats (O'Donnell et al. 2016). ...
In New Zealand, intensive, site-based conservation management of bird species is often focused on controlling threats from invasive species at a local scale. Such management may benefit species resident within the site but may be insufficient for mobile taxa whose movements extend beyond it through annual migrations, irregular nomadic movements, or exchanges of dispersing individuals in metapopulation networks. Here we highlight challenges in the conservation management of mobile species, and argue that information on population trends, vital rates (recruitment, survival, and immigration or emigration), movements, and population connectivity is required to understand whether threats at a particular time or place result in population limitation, and to evaluate different management options. We review and synthesise current knowledge on the vital rates of a group of migratory wading birds endemic to New Zealand: pohowera/banded dotterel (Charadrius bicinctus), tarāpunga/black-billed gull (Larus bulleri), tarapirohe/black-fronted tern (Chlidonias albostriatus),tōrea/South Island pied oystercatcher (Haematopus finschi), and ngutu parore/wrybill (Anarhynchus frontalis).We identify knowledge gaps for these species about population trends, connectivity, and movement, and show that information on egg and chick survival is available for all species, but information on adult survival rates is scarce and only available for three species. Because dispersal and migration dynamics link geographically distant sites, greater recognition of population dynamics dependent on the full annual cycle is required to improve conservation actions and robustly assess management outcomes. We discuss how ecological understanding and conservation of mobile species can be advanced by technological developments coupled with new integrative modelling frameworks that incorporate existing data.
... It inhabits the entire Korean Peninsula, predominantly coastal areas, agricultural landscapes, and forests (Kim et al. 2013;Jo, Baccus, and Koprowski 2018). BR infestations cause catastrophic declines in the populations of native species worldwide (Harris 2009;Sanders and Maloney 2002;King, Foster, and Miller 2011;Banks and Hughes 2012;Jones et al. 2008;Saunier et al. 2024). In South Korea, several marine breeding birds including the Chinese crested tern (Thalasseus bernsteini), a globally critically endangered species, have been disrupted by BR infestations on many uninhabited islands (Gang et al. 2008;Park et al. 2023;Kang et al. 2022). ...
The distribution of mammalian pests is altered by changes in global climate and land cover. Rattus norvegicus is a significant pest that contributes to the catastrophic decline of native species. Therefore, the studies identifying potentially suitable habitats for Rattus norvegicus and the impact of future climate change on the extent of such habitats are crucial. In this study, we determined the effects of key environmental and ecological variables on Rattus norvegicus in South Korea by considering multiple climate changes, land cover, and dispersal scenarios. The available presence locations with the least correlated variables and Maximum Entropy (MaxEnt) model along with multiple Shared Socioeconomic Pathways (SSPs) scenarios were utilized to project current and future habitat suitability. Additionally, three dispersal scenarios were incorporated into the model to enrich the analysis of potential future distribution. Mean diurnal temperature, elevation, and nighttime light were the three most important variables contributing to the species' distribution. The coastal and northern regions of South Korea constitute currently suitable habitats and are expected to exhibit a significant increase in the species' population under future climate projections. The results demonstrate the potential expansion of Rattus norvegicus as a result of changes in climate and land cover and provide crucial insights into the species' environmental niches. This study highlights the potential areas for monitoring, early warning, and developing effective prevention and control strategies for Rattus norvegicus.
... In recent decades, significant resources have been invested in research to determine the underlying causes of these population declines, and a number of causal factors have been identified (O'Donnell et al. 2016). These include depredation by introduced mammalian and native avian predators (Sanders & Maloney 2002;Steffens et al. 2012;Cruz et al. 2013;Norbury et al. 2021), habitat loss and degradation caused by invasive weeds, water abstraction, flood mitigation activities, land use changes and humaninduced climate change (Maloney et al. 1999;Robertson & Heather 1999;Norbury & Heyward 2008;McGlone & Walker 2011;O'Donnell & Hoare 2011), and disturbance caused by human activities, such as the recreational use of coastal and riverine habitats (Kearvell 2011). Substantial efforts are now underway throughout New Zealand to reduce these threats to local shorebird populations. ...
Egg floatation is a technique which can be used to estimate egg age and hatching dates of New Zealand shorebird eggs. It can be used to improve the accuracy of nest survival models, help identify nest outcomes, assist with chick survival monitoring and to prioritise the capture of incubating birds. We used egg floatation to estimate the age and hatching dates of South Island pied oystercatcher (Haematopus finschi) (SIPO) eggs. We developed regression equations to estimate the age of SIPO eggs by modelling egg angle and egg float height against egg age using a sample of eggs with known hatch dates. For early incubation eggs, we used linear regression to model the relationship between egg age and egg angle only, whereas for late incubation eggs we used multiple regression to model the relationship between egg age and both egg angle and egg float height data. These equations allowed 90% of SIPO eggs to be aged to within five days of their actual age. We recommend that species-specific regression equations describing the relationship between egg float characteristics and egg age be developed for other New Zealand shorebird species, to aid future research, monitoring and conservation management actions on these species. McArthur, N.J.; Krouse, S.K.; Thomas, D.; Thompson, H.; Melville, D.S.; Williams, E.M.; Walker, S.; Schlesselmann, A-K.V. 2024. Using egg floatation to estimate the age and hatching dates of South Island pied oystercatcher (Haematopus finschi) eggs. Notornis 71(2): 37-45.
... While the economic damage of cyclone Gabrielle has been estimated to be around 14 billion New Zealand dollars (Wilson et al., 2023), the impacts of the extensive floodings and heavy storms on Aotearoa New Zealand's biodiversity remain largely unclear but can be assumed to be severe (Bateman et al., 2020;Keegan et al., 2022). The little available research predominantly focuses on waterfowl and sea birds (Davis, 1994;Sanders and Maloney, 2002) but it is likely that other ground-nesting, groundforaging and small-bodies species may also be negatively impacted by floods and severe weather (Miskelly and Sagar, 2008;Reiley et al., 2017).Drought and fire risk are also predicted to increase across Aotearoa New Zealand (Macinnis-Ng et al., 2024;Sood and Mullan, 2020). Droughts appear to be a severe threat to endemic species like weka Gallirallus australis and kiwi species (Beauchamp et al., 1999;Wilson, 2014) and are likely to have severe effects on population numbers and may induce range shifts (Cady et al., 2019). ...
Anthropogenic climate change is threatening biodiversity globally with many species facing higher extinction risks. In Aotearoa New Zealand, average temperatures have increased by 1.13 • C since preindustrial times. While threats to many Aotearoa New Zealand bird species from invasive species and habitat destruction and degradation are largely well known, the impacts of climate change on Aotearoa New Zealand's biota and how these interact with existing threats remain largely unclear. To assess predicted future range shifts for terrestrial Aotearoa New Zealand's bird species, species distribution models were performed using Maxent. The results of these models were then integrated into a trait-based vulnerability assessment to create a combined correlative-/trait-based approach accounting for both extrinsic and intrinsic factors of species' vulnerability to climate change. Most assessed species scored moderately to highly vulnerable to climate change. Alpine species, colder-dwelling species on the South Island, species with significantly restricted ranges and already endangered species displayed the highest vulnerability to climate change. Several introduced species were identified to have a very high risk of becoming invasive with future climate change, with range shifts and low vulnerability highlighting the potential to outcompete native species. The climate change vulnerability assessment provides novel insights and fills a knowledge gap regarding potential climate change impacts on Aotearoa New Zealand birds. These results are important for integrating climate change into conservation planning to ensure long-term success of current conservation efforts.
... Wrybills reach the Firth of Thames from their breeding grounds from the last week of December onwards (Davies 1997), and the moult scores of the carcasses found are consistent with them having been killed at a similar time to the terns and the oystercatcher. Three of the wrybills were about Evidence of the impacts of introduced mammals on breeding shorebirds in New Zealand is accumulating (e.g., Dowding & Murphy 2001;Sanders & Maloney 2002). Here we describe an instance of predation by mammals on wrybills (Anarhynchus frontalis) on one of their main non-breeding grounds (Sagar et al. 1999), the Firth of Thames. ...
... Non-targeted incidental predation among grassland birds was well (Nolan, 1963 andRicklefs, 1969). In grassland birds non-targeted mammalian predator account for most predation which mostly visit between sunset and sunrise (Maxson and Oring 1978) (Sanders and Maloney 2002). However, a wide variety of predators, including birds, snakes and mammals generally cause nest losses among grassland birds (Gottfried and Thompson 1978, Maxson and Oring 1978, Wray and Whitmore, 1979. ...
Bengal florican (Houbaropsis bengalensis) is an important species of the three bustard present in Indian subcontinent. It is critically endangered bustard of the family otididae. Bengal Florican is a medium size about 60 cm size at standing position bustard its basically ground niche. The Bengal florican (Houbaropsis bengalensis) basically preferred open grassland dominated with Imperata cylindrical, Saccharum munja and Desmostachya bipinnata, the population of the Bengal florican due to habitat loss through environmental change and anthropologic activities. During the study period in Dudhwa National Park we observed only 13 males and 3 females of Bengal Florican. Total 80 grasslands covering 206.85 Km 2 areas were surveyed. Out of this presence of Bengal Florican was found only in seven large grasslands (12.63 ± 9.12 Km 2). In the adjoining small grasslands (1.14 ± 2.81 Km 2) Bengal Florican was not found. Island biogeography model indicates that large island will have a greater number of species than Small Island. Species-area relationship has been used to predict the number and percentage of those species that would become extinct if habitats destroy.
... Nest predation is a major factor limiting the success of bird reproduction and affects the life history and population dynamics of birds (Reidy and Thompson, 2012;Thompson and Ribic, 2012;Ibáñez-Álamo et al., 2015;Chen et al., 2020). Especially for ground-nesting birds, nest predation has become one of the most critical factors affecting their reproductive performance and population growth (Sanders and Maloney, 2002;MacDonald and Bolton, 2008;Pedersen et al., 2011;Melville et al., 2014). Based on this, understanding predation on birds and its influencing factors is of great significance for studying bird population dynamics and proposing conservation strategies (Martin, 1993;Chalfoun et al., 2002;Seibold et al., 2013;Chen et al., 2020). ...
Breeding success is an important factor determining fecundity with nest predation being the main factor limiting avian breeding success. Understanding of nest predation and its influencing factors are highly significant to explore the dynamics of bird populations and developing appropriate conservation strategies. In two breeding seasons of the year 2020 and 2021, natural nests of the red junglefowl (Gallus gallus jabouillei) were systematically searched and monitored using infrared camera, in two nature reserves (Datian and Bangxi) of tropical Hainan island, China. Results showed that breeding season of the red junglefowl is mainly from March to July, with April being the breeding peak. The clutch size was 5.15 ± 1.28 (n = 13), and nesting success of natural nests was 31.2%, with nest predation accounting for 45.4% of nest failure. Artificial nest experiments showed that predation rates of artificial nests were 25% (Datian, 2020), 6.67% (Datian, 2021), and 0% (Bangxi, 2020). Rodents, reptiles, and coucals are the main nest predators of red junglefowls, while activities of Hainan Eld’s deers (Panolia siamensis) may interfere with the reproduction of red junglefowls. We suggest that the conservation management policies should consider the impacts on junglefowls’ breeding success when reconstructing the suitable habitat of the Hainan Eld’s deer.
... The first studies date back to the fifties of the last century 21,22 and technological innovations have allowed significant advances in improving both the quantity and the quality of the images received, going from the first prototypes based on 35 mm photographic cameras to video surveillance cameras remotely controlled that allows real-time monitoring and public access through the Internet (review in 23 ). Although most studies report neutral effects of the use of cameras inside nests (e.g., 5,18,[24][25][26][27] ), very few studies report the possible potential effects that the installation of electronic devices inside nests might cause on behaviour (e.g. avoidance, decrease in the frequency of visits to the nest, nest abandonment) or direct and indirect effects on breeding performance (e.g. increase or decrease in predation risk, reduction in productivity of remotely-monitored nests). ...
Video surveillance cameras installed on birds’ nests are a cost-effective tool to study many aspects of ecology and behaviour that would otherwise be practically impossible to obtain. However, although most studies report neutral effects of cameras on birds, very few studies analyse in detail the potential negative effects of their use, particularly on raptors. Here, using a long-term database of a population of Bonelli’s eagle ( Aquila fasciata ) collected from 2000 to 2022, I show how the inappropriate use of video surveillance cameras could result in negative effects on the reproduction of a threatened species through a before-and-after control-impact study design. Pairs under video surveillance showed lower productivity, lower breeding success and unusual delayed laying dates. The installation of cameras close to the laying date, coinciding with the mating phase of individuals, most of them subadult inexperienced birds; in combination to the reiteration of visits to the nests once the cameras were installed to check the system, particularly during the incubation period and early stages of breeding; and the installation of cameras in a particular area subject to constant human disturbance, might explain these results. Potential management actions to mitigate the effect of the installation of video cameras on birds’ behaviour should include the need to plan the intervention dates, testing the systems beforehand under controlled conditions and adequate post-installation monitoring to avoid unnecessary disturbance to animals. Finally, I urge the scientific community to report the potential negative effects observed in their studies, especially if the target species are threatened with extinction.
... Parental care may be defined as any strategy that increases offspring fitness, 1,2 and involves two major decisions: how long to care and how much to care. 3,4 Parental care may affect adult survival, [5][6][7][8] and may be in conflict with other activities of adults, such as courtship behaviour or feeding, thus reducing mating opportunities, which leads to a sexual conflict over offspring care. 4,9 This conflict affects the decisions of adults on the timing of brood desertion. ...
Studies on brood desertion in birds have been mainly conducted on species with biparental care, and less often on uniparental species. Females of many duck species remain with their ducklings, unassisted by males, during variable periods of time before the chicks can fledge. In this paper, we examined factors that influence brood desertion by female red-crested pochards ( Netta rufina), common pochards ( Aythya ferina) and white-headed ducks ( Oxyura leucocephala) during a 10-year period in lakes in southern Spain that experienced interannual variations in water levels. At an interspecific level, we found that brood desertion was less frequent in the species that nested earlier (red-crested pochard), while it was more frequent in the species that nested later (white-headed duck). Larger (older) ducklings were deserted more frequently than smaller ones in the three species. However, an interaction between flooding conditions in wetlands and species identity on brood desertion, after accounting for chick age, suggests that there were variations between the ducklings of the three species in their requirements for maternal care, conditioned by environmental conditions. Therefore, our study indicates that environmental conditions may affect parental care. A longer duration of brood attendance by female ducks may buffer against adverse effects of environmental conditions.
... Because of the naivety of many island birds to predation and the consequential lack of behavioural, morphological and other life history antipredator responses, the impact of introduced mammals has been devastating, often leading to local or even global extinction (Atkinson 2001, Courchamp et al. 2003, Towns et al. 2006. Birds are particularly sensitive to predators during their reproduction stage, as predators may affect eggs, chicks and adults (Sanders & Maloney 2002). Nest success monitoring can help evaluate these short-term effects (Jones et al. 2008). ...
RESUMO A calhandra-do-ilhéu-Raso Alauda razae é uma das aves mais raras e ameaçadas do mundo. Esta espécie esteve confinada ao Raso até à translocação em 2018 para a ilha vizinha Santa Luzia. A sobrevivência desta está altamente dependente do tempo de incubação bem-sucedido e de riscos baixos de predação. Neste estudo, primeiramente identificámos potenciais predadores por meio de armadilhas de isco em Santa Luzia. Posteriormente, avaliámos o impacto relativo das espécies de predadores na sobrevivência com ninhos experimentais. O rato-doméstico Mus musculus foi capturado em todos os locais em densidade duas vezes superior no sul. As experiências com ninhos artificiais sugeriram um forte impacto predatório sobre os ovos. Identificámos pelo menos dois tipos diferentes de provável predação de ninhos: nocturno (atribuído a ratos), afectando 25-50% dos ovos, e diurno (atribuído provavelmente ao corvo-do-deserto Corvus ruficollis), afectando até 100% dos ovos. Actualmente, as taxas de sucesso de nidificação das calhandras do Raso permanecem pouco estudadas, mas é considerado naturalmente muito baixo no Raso, sem mamíferos introduzidos, devido à forte predação pela osga gigante Tarentola gigas, ela própria uma espécie ameaçada. A adaptação desta ave a diferentes ecossistemas e à pressão de predação será crucial para a sobrevivência a longo prazo. Palavras-chave: conservação de ilhas, erradicação, ilhas Desertas, roedores invasores Caut & Jowers 4 Predation risk of Raso lark ABSTRACT The Raso lark Alauda razae is one of the rarest and most threatened birds worldwide. This species was confined to Raso until its translocation in 2018 to the nearby Santa Luzia Island. Its survival is high dependent on successful incubation time and minimal predation risk. In this study, we firstly identified potential predators through bait trapping on Santa Luzia. Secondly, we assessed the relative impact of predator species on experimental nest survival. The house mouse Mus musculus was captured at all sites with a density twofold higher in the southern area. The artificial nest experiments suggested a heavy predatory impact on eggs. We identified at least two different types of likely predation of nests: nocturnal (assigned to mice), affecting 25-50% of eggs, and diurnal (assigned probably to brown-necked raven Corvus ruficollis), affecting up to 100% of eggs. Currently, the Raso lark nest success rates remain poorly studied but it is considered to be very naturally low on Raso, which is free of any introduced mammals, owing to heavy predation by the giant gecko Tarentola gigas, itself a threatened species. The adaptation of this bird to different ecosystems and predation pressure will be crucial for its long-term survival.
... However, other anthropogenic impacts and environmental modifications to NZ also include the introduction of exotic fauna and flora (King 1984). Alien, predatory mammals have had particular devastating effects on NZ's native avifauna (Sanders & Maloney 2002, Innes et al. 2010). Many extant native species are still vulnerable to predation and habitat loss, and have declined significantly (Robertson et al. 2021). ...
Understanding how climatic and environmental changes, as well as human activities, induce changes in distribution and population size of avian species refines the ability to predict future impacts on threatened species. Using multilocus genetic data, we show that the population of a threatened New Zealand endemic open‐habitat specialist, the Black‐fronted Tern Chlidonias albostriatus – in contrast to forest specialists – expanded during the last glacial period. The population has decreased subsequently despite the availability of extensive open habitat after human arrival to New Zealand. We conclude that population changes for open habitat specialist such as Black‐fronted Terns in pre‐human New Zealand were habitat dependent, similar to Northern Hemisphere cold‐adapted species, while post human settlement populations were constrained by predators independent of habitat availability similar to other island endemic species.
... As part of a larger study, we monitored a subset of nests at both properties with video surveillance to determine nest predator ID. Surveillance cameras were small, camouflaged, and used infrared light, which is discrete in the dark and likely not detectable by most predators (Sanders & Maloney, 2002). ...
Disruption of historic fire regimes has led to the expansion of hardwoods into pine savanna ecosystems in the southeastern United States. Management strategies that reduce mature mesophytic oaks in pine savanna that was previously fire suppressed may help restore understory vegetation and positively affect understory birds. Many private lands in the Southeast are managed intentionally for the Northern Bobwhite (Colinus virginianus; hereafter bobwhite), a species with high cultural and economic importance to the region. Mechanical hardwood reduction is used to restore southeastern pine savanna and as a pre-dation management tool to enhance populations of bobwhite although its utility has not been empirically tested. We measured the demographic response of bobwhite to a large-scale hardwood reduction using a before-after-control-impact (BACI) study replicated at two properties in the Red Hills region of northern Florida, United States, that had a relatively low density of mature, mesophytic hardwoods and were already managed for bobwhite with 2-year fire return intervals, supplemental feeding, and meso-mammal control. We monitored reproduction at 561 nests and survival of 1529 adults tracked with radiotelemetry. In treated sites, mean daily nest survival was 0.98 and did not change following hardwood reduction. Reproductive effort declined each year (pre-and post-treatment; 2015-2018) in one treated site and varied relatively little in the other. At both treated sites, weekly adult survival decreased to 0.93-0.94 immediately following the treatment, then increased gradually but did not exceed pretreatment weekly survival (0.98) within 2-3 years following the treatment. Our results suggest hardwood reduction may not benefit bob-white adult survival or productivity within 2-3 years of application on sites that are already managed intensively with prescribed fire, predator control, and supplemental feeding and that hardwoods in this system may not have direct negative impacts on understory birds. Further study is necessary to determine under what conditions hardwood reduction may be beneficial and whether other metrics such as chick survival or immigration are affected. Our study sites represent typical land management in the Red Hills region, and we
... Kakī are a critically endangered wading bird endemic to the South Island of Aotearoa New Zealand. While Kakī were once more widespread in Aotearoa, they experienced decline due to introduced mammalian predators and habitat loss (Sanders & Maloney, 2002). ...
Researchers have long debated which estimator of relatedness best captures the degree of relationship between two individuals. In the genomics era, this debate continues, with relatedness estimates being sensitive to the methods used to generate markers, marker quality, and levels of diversity in sampled individuals. Here, we compare six commonly used genome‐based relatedness estimators (kinship genetic distance (KGD), Wang Maximum Likelihood (TrioML), Queller and Goodnight (Rxy), Kinship INference for Genome‐wide association studies (KING‐robust), and Pairwise Relatedness (RAB), allele‐sharing co‐ancestry (AS)) across five species bred in captivity–including three birds and two mammals–with varying degrees of reliable pedigree data, using reduced‐representation and whole genome resequencing data. Genome‐based relatedness estimates varied widely across estimators, sequencing methods, and species, yet the most consistent results for known first order relationships were found using Rxy, RAB, and AS. However, AS was found to be less consistently correlated with known pedigree relatedness than either Rxy or RAB. Our combined results indicate there is not a single genome‐based estimator that is ideal across different species and data types. To determine the most appropriate genome‐based relatedness estimator for each new dataset, we recommend assessing the relative: (1) correlation of candidate estimators with known relationships in the pedigree and (2) precision of candidate estimators with known first‐order relationships. These recommendations are broadly applicable to conservation breeding programs, particularly where genome‐based estimates of relatedness can complement and complete poorly pedigreed populations. Given a growing interest in the application of wild pedigrees, our results are also applicable to in‐situ wildlife management.
... Reuleaux et al., 2014;Bonaparte and Cockle, 2017), observing behaviour at the nest (e.g. Sanders and Maloney, 2002;Richardson et al., 2009) and monitoring predation (e.g. Clout and Merton, 1998;Masello et al., 2006;Ribeiro-Silva et al., 2018). ...
Knowledge of breeding success and its limiting factors is crucial in assessing species’ conservation needs. As cavity-nesters, parrots are particularly influenced by the availability of suitable cavities and low breeding output, whether due to natural processes or trapping. On the island of Sumba, Indonesia, the Critically Endangered Citron-crested Cockatoo (Cacatua citrinocristata) has the added problem of co-existing with an unusually rich hole-nesting bird community in a forested environment much constrained by habitat loss. We monitored 95 nesting cavities of cockatoos and their competitors and potential nest-predators, over one to four breeding seasons, using a combination of camera-traps, direct checks on nest contents, and observations from the ground. Competition for suitable cavities was intense among three large parrot species, two owls and a hornbill. Visitation rates by potential competitors were higher at unoccupied cavities than at those containing active nests, reflecting the guarding behaviour of the occupants. The Endangered Sumba Hornbill (Rhyticeros everetti) dominated observed direct confrontations and was the most frequent visitor to active parrot nests, suggesting a further role as a potential nest-predator. Cockatoos prospected many cavities but rarely then attempted to nest: instead the sites were usually occupied by other cavity-nesters, or by bees. At the few cavities where cockatoos did breed, predation pressure was likely low, and observed success rate high (10 successful of 15 nests), although the low number of nests found early in the breeding cycle suggests that some may have failed before detection. Intense competition for cavities suggests a shortage of suitable nest-sites, the need for preservation of old hole bearing trees and a role for nestboxes. Accessible, known, safe artificial nest-sites would also provide opportunities to assess the scale of nest-site shortage, allow camera placements to study productivity, exclude some competitors and predators and prevent illegal trapping. Especially given continued trapping pressure, the species would benefit from targeted local awareness-raising and law enforcement, with the whole endeavour backed up by longer-term forest restoration.
... Kakī are a critically endangered wading bird endemic to the South Island of Aotearoa New Zealand. While Kakī were once more widespread in Aotearoa, they experienced decline due to introduced mammalian predators and habitat loss (Sanders & Maloney, 2002). ...
Researchers have long debated which genomic estimator of relatedness best captures the degree of relationship between two individuals. In the genomics era, this debate continues, with relatedness estimates being sensitive to the method used to generate genomic markers (e.g., reduced-representation sequencing, whole genome resequencing), marker quality, and levels of diversity in sampled individuals.
Here, we compare six commonly used relatedness estimators (kinship genetic distance (KGD), Wang Maximum Likelihood (TrioML), Queller and Goodnight (R xy ), KING-robust, R AB , allele-sharing co-ancestry) across five species bred in captivity–including three birds and two mammals–with varying degrees of reliable pedigree data, using reduced-representation and whole genome resequencing data.
Relatedness estimates varied widely across estimators, sequencing method, and species, yet the most consistent results with known pedigree data were found using KING-robust and to a lesser extent KGD. The allele-sharing estimator was sensitive to missing data and inbreeding, attributes that make this estimator ill-suited for use in captive breeding programs. Our combined results indicate there is not a single genomic based estimator that is ideal across different species and data types.
To enable researchers to evaluate the most appropriate relatedness estimator for each new data set, we provide a structured workflow that is broadly applicable to conservation breeding programs, particularly where genomic estimates of relatedness can complement and complete poorly pedigreed populations. Given a growing interest in wild pedigrees, our results and workflow are also applicable to in situ wildlife management.
... For additional concealment, we covered the first 1 m of the cord closest to the nest in camouflage tape. The cameras used infrared light, which is discrete in the dark and likely not detectable by most predators (Sanders and Maloney 2002). We had a limited number of video-surveillance systems; if all surveillance systems were in use on other nests at the time a new nest was found, then it was not monitored with video surveillance. ...
Where historical fire regimes have been disrupted, reduction in woody vegetation is often used to maintain or restore habitat for grassland and early successional birds. In pine savanna ecosystems of the southeastern USA, mechanical hardwood canopy reduction can restore pine savanna communities and is often employed on privately owned lands to improve habitat for the Northern Bobwhite (Colinus virginianus), although scant empirical evidence exists of its effects on target or non‐target species. We measured the response of a pine savanna specialist, the Bachman's Sparrow (Peucaea aestivalis), to large‐scale hardwood reduction in a before–after–control–impact design on two properties where two‐year fire‐return intervals were established and the Bachman's Sparrow population was stable. We investigated the effects of mechanical hardwood reduction on Bachman's Sparrow daily nest survival, cause‐specific nest mortality and adult male annual survival. During the four‐year study, we monitored 107 Bachman's Sparrow nests, recorded 49 nest predation events, and banded 113 adult male Bachman's Sparrows. We found Bachman's Sparrow nest and adult survival were resilient to changes in the hardwood canopy and did not differ significantly between treatment and control sites. Average annual adult male survival was 0.41 (0.32–0.52) and daily survival rate of nests with surveillance declined annually from 0.94 (0.92–0.96) to 0.88 (0.83–0.92). The identity of predators at nests was dominated by two snake species, black racer (Coluber constrictor) and corn snake (Pantherophis guttata). We found evidence for opposing treatment effects on the frequency of nest depredations by the dominant species; racers responded positively and corn snakes responded negatively. Our results suggest a moderate midstory canopy does not limit Bachman's Sparrow vital rates when management includes frequent prescribed fire. Our results also suggest hardwood reduction to mitigate nest predation may be complicated with a diverse predator suite.
... We simulated the observed waning of the treatment effect over 25 days by applying different values of nest-HS for successive renesting attempts: For first and second renesting attempts, we set HS as the mean of the first 25 days from the Cass/Macaulay sites (0.592), and for third renesting attempts, we set HS as the mean from all days (0.580). We used values recorded from the Cass/ Macaulay sites because they were more typical for double-banded plovers (HS on the Tekapo sites was low) (42,54). We set the starting population size to 1000 and the carrying capacity to five times the starting population. ...
Efficient decision-making integrates previous experience with new information. Tactical use of misinformation can alter choice in humans. Whether misinformation affects decision-making in other free-living species, including problem species, is unknown. Here, we show that sensory misinformation tactics can reduce the impacts of predators on vulnerable bird populations as effectively as lethal control. We repeatedly exposed invasive mammalian predators to unprofitable bird odors for 5 weeks before native shorebirds arrived for nesting and for 8 weeks thereafter. Chick production increased 1.7-fold at odor-treated sites over 25 to 35 days, with doubled or tripled odds of successful hatching, resulting in a 127% increase in modeled population size in 25 years. We demonstrate that decision-making processes that respond to changes in information reliability are vulnerable to tactical manipulation by misinformation. Altering perceptions of prey availability offers an innovative, nonlethal approach to managing problem predators and improving conservation outcomes for threatened species.
... The uplands of the Mackenzie Basin in New Zealand's central South Island is an ecologicallydistinct region comprised of the country's tallest mountains (to 3724 m a.s.l.), braided rivers, and expansive dryland tussock grassland. This region boasts high faunal and floral biodiversity and is a stronghold for many endemic threatened species (e.g., Maloney et al. 1997) which are collectively imperilled by 10 small mammal species (Sanders and Maloney 2002;Dowding et al. 2015). Several studies have sought to inform pest suppression efforts across this large area ([ 300,000 ha) by exploring fine-scale habitat selection and aspects of the spatial ecology of pest species, such as cats (Recio et al. 2014(Recio et al. , 2015Cross 2016), hedgehogs (Shanahan et al. 2007;Recio et al. 2013), ferrets (Byrom 2002, mice (Hunt 2018), and abundances and habitat selection of the greater predator guild (Keedwell and Brown 2001;Cameron et al. 2005). ...
New Zealand faces significant ecological problems caused by the introduction of a variety of invasive small mammal species. Many of these species originate from temperate to subarctic climates and occur across wide elevations in their native range, and so arrived predisposed to adapt to a variety of habitats and bioclimatic zones in their new environs, including the alpine zone. Almost all of New Zealand's invasive small mammal species have been recorded in the country's alpine zones, yet neither the altitudinal distribution nor the extent to which such species use high elevation areas has been clearly defined. We conducted extensive camera trap surveys in summer to autumn periods of 2019 and 2020 across an elevation range of 500-2250 m above sea level, and used detection rates and occupancy modelling to reveal the altitudinal distributions and habitat associations of all 10 invasive small mammals that occur in the dryland zone of the central South Island. We found altitudinal distributions varied greatly across species, and that while most exhibited decreasing detection rates and site occupancy probabilities with increasing elevation, some used the subalpine and alpine zones to a greater degree than adjacent lower elevations. There were clear habitat associations, as well as interspecific associations that helped to explain the altitudinal distribution of some species. Understanding how such factors influence the distribution of invasive small mammals has both broad implications for invasive species management, and direct applications in evaluating threats to native taxa, advancing management strategies, and benchmarking distributions in a changing climate.
... However, the replacement of cameras three times during 2.5 days, but probably no similar frequency of close visits at the control group, was a massive disturbance that could have biased nest failure (McKinnon and Bêty 2009). Thus, in the literature there is a broad consensus that the appropriate use of nest cameras does not affect hatching success of ground nesting birds (see also Sanders and Maloney 2002, Herring et al. 2011, Mallord et al. 2012, Ellis-Felege and Carroll 2012, Andes et al. 2019. ...
Identifying the fate of birds’ nests and the causes of breeding failure is often crucial for the development of conservation strategies for threatened species. However, collecting these data by repeatedly visiting nests might itself contribute to nest failure or bias. To solve this dilemma, automatic cameras have increasingly been used as a time-efficient means for nest monitoring. Here, we consider whether the use of cameras itself may influence hatching success of nests of the Black-tailed Godwit Limosa limosa at two long-term study sites in northern Germany. Annually between 2013 and 2019, cameras were used to monitor godwit nests. In 2014 and 2019, nests were randomly equipped with cameras or not, and nest survival checked independently of the cameras. Nest-survival models indicated that survival probabilities varied between years, sites and with time of the season, but were unaffected by the presence of cameras. Even though predation is the main cause of hatching failure in our study system, we conclude that predators did not learn to associate cameras with food either when the cameras were initially installed or after they had been used for several years. Cameras were thus an effective and non-deleterious tool to collect data for conservation in this case. As other bird species may react differently to cameras at their nests, and as other sets of predators may differ in their ability to associate cameras with food, the effect of cameras on breeding success should be carefully monitored when they are used in a new study system.
... Lack of standardized monitoring meant we could not account for impacts of other mammalian predators (e.g., Felis catus, feral cat; Erinaceus europaeus, European hedgehog) that may have been present at varying abundances in unfenced ecosanctuaries (Hendra 1999), yet the absence of these species from eradicationfocused regimes may have contributed to their positive bird responses. Feral cats and European hedgehogs are less frequent targets of pest control in New Zealand but can have severe impacts on native invertebrates (Jones et al. 2013), herpetofauna (Spitzen-van der Sluijs et al. 2009, Woinarski et al. 2018, ground-nesting birds (Sanders andMaloney 2002, Innes et al. 2010), and other small mammals (Loss et al. 2013, Woinarski et al. 2019 worldwide. Long-term invertebrate, vegetation, and herpetofauna studies were under-represented compared to birds, particularly within peninsula-fenced ecosanctuaries, as were beech forest ecosanctuaries where small mammals undergo irruptive dynamics (King 1983, Ostfeld and Keesing 2000, O'Donnell and Hoare 2012, Elliott and Kemp 2016, Walker et al. 2019. ...
Invasions by alien pest species contribute heavily to global biodiversity decline, with invasive mammals having some of the greatest impacts on endemic biota. Pest management within ecological restorations is therefore critical for conserving threatened biota. Coordinating restoration efforts at global scale requires evidence of the relative efficacy of different pest‐managed restoration approaches (“regimes”) for enhancing biodiversity. Our national meta‐analysis of 447 biodiversity responses across 16 ecological restorations quantifies significant benefits for biodiversity over two decades and multiple trophic levels, and across a spectrum of invasive mammal suppression‐to‐eradication regimes. Deeply endemic species had the strongest responses to pest control compared with recent native or introduced biota. Using this information, we predict levels of pest suppression required to confer biodiversity benefits, to guide future management strategies. Our findings provide new evidence that invasive pest control is an effective approach to ecological restoration, to aid decision‐makers in setting objectives and making targeted investments.
... Both humans and dogs are considered predators by shorebirds (Roberts & Evans 1993, Schulz & Stock 1993, Lafferty 2001b, Burger et al. 2004, Le Corre et al. 2009, Webber et al. 2013, Weston & Stankowich 2014. In fact, the occurrence of predation of nests, adults and plover chicks by dogs has been documented in various breeding habitats (Nol & Brooks 1982, Fraga & Amat 1996, Sanders & Maloney 2002, Amat & Masero 2004a, Diniz et al. 2016 and it is estimated that it may be an important mortality factor (Montalvo & Figuerola 2006, Baudains & Lloyd 2007. Dogs cause significant disturbance to birds when they approach them (Burger 1981, Klein 1993, and have a stronger effect on their behaviour than people do (Lord et al. 2001, Glover et al. 2011, Weston & Stankowich 2014, Faillace & Smith 2016, Jorgensen et al. 2016. ...
Recreational activities in nature have increased considerably in recent decades. Human disturbance may trigger similar trade‐offs in birds that the natural risk of predation generates on productivity through parental investment decisions. In order to estimate how the impact of human presence affects breeding birds on Mediterranean beaches, the behaviour of incubating Kentish plovers (Charadrius alexandrinus) was studied in relation to the approach of people, vehicles and dogs. Observational data were collected and control experiments were performed with a standardized stimulus. The response variability of birds in the decision to flush from the nest was studied depending on the type of beach user, the location of the disturbance event and thermal stress. Walkers, when accompanied by dogs, flushed plovers 93.8% of the time when walking through dunes and 80.0% of the time when walking on paths, whereas pedestrians alone flushed plovers 47.6% of the time when in dunes and only 12.9% of the time when on paths. Lone dogs triggered a flushing response 100% of the time when they roamed the dunes and 50% on the shore. The number of users in each disturbance event did not affect the flushing behaviour. Nest return times were shorter on disturbed beaches, suggesting habituation to the human disturbance stimulus. The ambient temperature for the nests in which plovers flushed was lower and nest return time decreased proportionally with ambient temperature, both suggesting that habituation to the human disturbance stimulus encourages relaxation of the trade‐off between escape behaviour to avoid predation risk and the effects of thermal stress on unattended eggs. Females flushed more frequently (57.1%) than males (32.0%), suggesting that they may perceive risk differently. Establishing buffers between nesting areas and people may help birds habituate to the predictable and non‐lethal stimulus of human presence, facilitating coexistence between conservation and recreation.
... In combination with other threats to braided river birds such as ongoing habitat loss and predation (Sanders & Maloney 2002;Cruz et al. 2013), the increased frequency of damaging extreme weather events is likely to negatively affect the population trajectories of already threatened and at-risk species. Braided river birds are often considered well-adapted to breeding within an unstable and flood-prone ecosystem and many species are able to renest in response to losses (Beer 1966;Hughey 1985). ...
... Conversely, all three predators have had only recent experience (up to 200 yr) with Masked Lapwings Vanellus mile, Family Charadriidae, Order Charadriiformes and Southern Black-backed Gulls Larus dominicanus, Family Laridae, Order Charadriiformes (Parkes and Murphy 2003), although they may have evolutionary experience with related species. All three species of predator inflict significant damage on a range of native bird populations in New Zealand and sub-Antarctic islands (Sanders and Maloney 2002, Jones and Norbury 2006, Angel et al. 2009), many of which are from the Order Charadriiformes. ...
Invasive mammalian predators can cause the decline and extinction of vulnerable native species. Many invasive mammalian predators are dietary generalists that hunt a variety of prey. These predators often rely upon olfaction when foraging, particularly at night. Little is understood about how prey odor cues are used to inform foraging decisions. Prey cues can vary spatially and temporally in their association with prey and can either reveal the location of prey or lead to unsuccessful foraging. Here we examine how two wild‐caught invasive mammalian bird predator species (European hedgehogs Erinaceus europaeus and ferrets Mustela putorius furo) respond to unrewarded bird odors over successive exposures, first demonstrating that the odors are perceptually different using house mice (Mus musculus) as a biological olfactometer. We aim to test if introduced predators categorize odor cues of similar prey together, a tactic that could increase foraging efficiency. We exposed house mice to the odors using a standard habituation/dishabituation test in a laboratory setting, and wild‐caught European hedgehogs and ferrets in an outdoor enclosure using a similar procedure. Mice discriminated among all bird odors presented, showing more interest in chicken odor than quail or gull odor. Both predator species showed a decline in interest toward unrewarded prey odor (i.e., habituation), but only ferrets generalized their response from one unrewarded bird odor to another bird odor. Hedgehog responses to unrewarded bird odors were highly variable between individuals. Taken together, our results reveal interspecific and intraspecific differences in response to prey odors, which we argue are a consequence of different diet breadth, life and evolutionary histories, and the conditions in each experiment. Generalization of prey odors may have enabled some species of invasive predators to efficiently hunt a range of intraguild prey species, for example, ground‐nesting shorebirds. Olfactory manipulation of predators may be a useful conservation tool for threatened prey if it reduces the conspicuousness of vulnerable prey.
... Ruffed grouse are female-only, continuous incubators that may renest if their initial nesting attempt fails, but that raise only one brood of precocial young per year (Rusch et al. 2000). As ground-nesting birds, most ruffed grouse nests fail because eggs are destroyed by predators (Bump et al. 1947, Bergerud andGratson 1988), however nests may also fail if the incubating female is killed by a predator while nesting (Lima 2009), if the nest is abandoned by the female (Ricklefs 1969, Pierce andSimons 1986), or because of weather-related events such as flooding (Sanders and Maloney 2002). Each of these outcomes may be influenced, in part, by characteristics of habitat at the nest site (Redmond et al. 1982, Moynahan et al. 2006. ...
Effective wildlife management requires a broad understanding of how forest structure and composition influence habitat use and vital rates during all aspects of species' life-cycles, however habitat characteristics may have variable importance during different life phases. Even though the ruffed grouse Bonasa umbellus is a popular game bird that has long been a focal species for management, a greater understanding of the links between forest characteristics and components of ruffed grouse reproduction would enhance managers' ability to promote the species. We monitored 45 nests belonging to 37 females during 20152017 in central Maine, USA, and evaluated the influence of forest characteristics on nest-site selection, nest survival and female survival while nesting. Ruffed grouse females selected nest sites with greater horizontal visual obstruction ( = 0.16 0.06 85% CI) than found at other sites that were locally available to them, however this characteristic did not appear to improve nest survival or female survival while nesting. Cumulative nest success was 42.8% and daily nest survival was reduced when coarse woody debris (CWD) was present at nest sites ( = 0.41 0.33 85% CI), but we found no evidence that other habitat characteristics or features of nests themselves were related to nest survival. However, reduced female survival while nesting was associated with presence of CWD ( = 1.27 0.91 85% CI), greater tree basal area ( = 0.96 0.81 85% CI) and greater conifer stem density ( = 0.45 0.28 85% CI) at nest sites; females had a 74.4% chance of survival during the length of time required to successfully nest. Our results demonstrate the importance of forest characteristics on multiple components of species' nesting ecology, and we provided management suggestions to promote attractive ruffed grouse nesting habitat while potentially mitigating sources of nesting failure.
... Once found on both main islands of Aotearoa, kakī experienced significant population declines throughout the 20th century due to introduced mammalian predators (e.g., feral cats, Felis catus; stoats, Mustela erminea; and hedgehogs, Erinaceus europaeus) along with braided river habitat loss and degradation (Sanders & Maloney, 2002). Today, an estimated 129 kakī are largely restricted to braided rivers of Te Manahuna/The Mackenzie Basin (Department of Conservation, personal comm.; Figure 1a) and recovery efforts include a conservation breeding programme that was initiated in the early 1980s (Reed, 1998). ...
Conservation management strategies for many highly threatened species include conservation breeding to prevent extinction and enhance recovery. Pairing decisions for these conservation breeding programmes can be informed by pedigree data to minimise relatedness between individuals in an effort to avoid inbreeding, maximise diversity, and maintain evolutionary potential. However, conservation breeding programmes struggle to use this approach when pedigrees are shallow or incomplete. While genetic data (i.e., microsatellites) can be used to estimate relatedness to inform pairing decisions, emerging evidence indicates this approach may lack precision in genetically depauperate species, and more effective estimates will likely be obtained from genomic data (i.e., thousands of genome‐wide single nucleotide polymorphisms, or SNPs). Here, we compare relatedness estimates and subsequent pairing decisions using pedigrees, microsatellites, and SNPs from whole genome resequencing approaches in two critically endangered birds endemic to New Zealand: kakī/black stilt (Himantopus novaezelandiae) and kākāriki karaka/orange‐fronted parakeet (Cyanoramphus malherbi). Our findings indicate that SNPs provide more precise estimates of relatedness than microsatellites when assessing empirical parent‐offspring and full sibling relationships. Further, our results show that relatedness estimates and subsequent pairing recommendations using PMx are most similar between pedigree‐ and SNP‐based approaches. These combined results indicate that in lieu of robust pedigrees, SNPs are an effective tool for informing pairing decisions, which has important implications for many poorly pedigreed conservation breeding programmes worldwide.
... Predation is another factor that can play an important role in regulating population trends (Tapper et al., 1996;Newton, 1998), especially in populations with low abundances (Sinclair et al., 1998;Burns et al., 2013). In the case of the ground-nesting birds, nest predation can be a significant factor affecting breeding success (Sanders and Maloney, 2002;MacDonald and Bolton, 2008), and high predation pressure can limit the recovery of endangered species that nest on the ground (Cuthbert and Hilton, 2004;Burns et al., 2013). In the current situation of population decline, any effort to reduce predation and increase the recruitment of these species could contribute to change this trajectory. ...
Populations of many ground-nesting bird species have declined substantially due to several factors, and pre-dation can be a leading contributor to these declines. As a method for reducing the nest predation on ground-nesting birds, we tested whether conditioned food aversion (CFA) can reduce red-legged partridge (Alectoris rufa) nest predation by red foxes (Vulpes vulpes). With a before-after control-impact design we deployed 1329 artificial nests in two different habitats in Central Spain using thiram as an aversive. Artificial nests were monitored by camera traps to identify the red fox individuals during the predation events. 26 foxes were GPS-tagged to monitor their spatial movements and feeding behavior. Partridge density and productivity were monitored to assess the thiram treatment effect on partridge population. Thiram treatment decreased artificial nest predation by foxes in both study sites by 26.8-50.1%, but this was compensated by an increased predation by other predators, possibly enhanced by the availability of our artificial nests. 78% of identified foxes that ingested thiram-treated eggs, stopped nest predation after treatment. Foxes maintained stable territories during the whole study period. Partridge productivity was 132-677% higher in thiram-treatment areas than in control areas, and partridge density after treatment increased more in thiram-treated areas (193-292%) than in control areas (1.8-99%). Our study shows that CFA reduced ground nest predation by foxes, and had a positive effect on the partridge population despite the compensatory predation. This method could be used as a non-lethal tool for conservation of endangered ground-nesting bird species.
... Once found on both main islands of Aotearoa, kakī experienced significant population declines throughout the 20th century due to introduced mammalian predators (e.g., cats, stoats, and hedgehogs) along with braided river habitat loss and degradation (Sanders & Maloney, 2002). Today, an estimated 129 kakī are largely restricted to braided rivers of Te Manahuna/The Mackenzie Basin (Department of Conservation, personal comm.; Figure 1A) and recovery efforts include a conservation breeding programme that was initiated in the early 1980's (Reed, 1998). ...
Conservation management strategies for many highly threatened species include conservation breeding to prevent extinction and enhance recovery. Pairing decisions for these conservation breeding programmes can be informed by pedigree data to minimise relatedness between individuals in an effort to avoid inbreeding, maximise diversity, and maintain evolutionary potential. However, conservation breeding programmes struggle to use this approach when pedigrees are shallow or incomplete. While genetic data (i.e., microsatellites) can be used to estimate relatedness to inform pairing decisions, emerging evidence indicates this approach lacks precision in genetically depauperate species, and more effective estimates will likely be obtained from genomic data (i.e., thousands of genome-wide single nucleotide polymorphisms, or SNPs). Here, we compare relatedness estimates using pedigree-, genetic-, and genomic-based approaches for making pairing decisions in two critically endangered birds endemic to New Zealand: kakī/black stilt (Himantopus novaezelandiae) and kākāriki karaka/orange-fronted parakeet (Cyanoramphus malherbi). Our findings indicate genetic-based estimates of relatedness are indeed the least precise when assessing known parent-offspring and full sibling relationships. Furthermore, our results show that relatedness estimates and subsequent pairing recommendations using PMx are most similar between pedigree- and genomic-based approaches. These combined results indicate that in lieu of robust pedigrees, SNPs are an effective tool for informing pairing decisions, which has exciting implications for many poorly pedigreed conservation breeding programmes worldwide.
... In Australia, the red fox Vulpes vulpes and feral cat Felis catus populate most of the mainland and many offshore islands [7]. Hedgehogs Erinaceus europaeus have been introduced to New Zealand and offshore islands in Europe, threatening ground-nesting birds [8,9]. Control of alien predators has brought about improvements in the conservation status of some species of declining native taxa [10], but eradication of most aliens remains difficult outside closed, isolated populations such as offshore islands [11,12]. ...
Alien mammalian predators are a major cause of species extinction and decline globally. Baits and lures, usually human-food based (for example meat, nuts or oils), are widely deployed in trapping programs to attract target species, but their effectiveness compared to other types of olfactory lures, for example social odours or prey odours, has never been systematically examined. Depending on the context, there can be high proportions of non-target captures, for example when targeting feral cats using cage traps, or low capture success, for example, when targeting introduced rats on tropical islands. Here we use a systematic process to map evidence on the effectiveness of different categories of olfactory attractants for invasive mammalian predators within different ecological contexts. We aim to look for where evidence clusters and knowledge gaps occur, for example, across different lure types or across different habitat-types, and highlight opportunities for future research into behaviourally-relevant olfactory lures. We will compile evidence from bibliographic databases, online search engines, government websites, specialist sites and expert contacts, and include ‘grey’ literature. Where possible, a Boolean-style full search string will be used, including Population, Intervention and Outcome search terms. Searches will be conducted in English, but a public request to the IUCN SSC Invasive Species Specialist Group (ISSG) will be made for literature including in languages other than English. Search comprehensiveness will be evaluated against 25 benchmark articles known to the authors. We will base inclusion of articles on presence of quantitative data, subject identity (invasive mammalian predator species), comparator (more than one type of olfactory lure assessed or lure compared to a control) and outcome (quantified attraction to lures or controls). Inclusion consistency checks will be performed with 10% of the titles and abstracts and 10% of the full texts. We will critically appraise the literature only on the basis of study design (e.g. appropriate controls) and sample size, rather than interpret the results. Finally, we will develop a searchable literature database accompanied by systematic ‘heat’ maps to visually represent knowledge clusters and gaps within different subsets of evidence, and a narrative synthesis of the evidence.
... Cub mortality has been observed for black bear (Ursus americanus) from flooding of natal dens (Alt 1984, White et al. 2001), but flooding after den emergence reportedly does not affect recruitment (Clark et al. 2017). Reptiles and ground-nesting birds may suffer reproductive failures when nests are inundated (Kushlan and Jacobsen 1990, Janzen 1994, Sanders and Maloney 2002. Flood timing relative to reproductive stage is therefore a critical consideration. ...
Effective deer management requires managers to distinguish between the density‐dependent influence of harvest and local environmental factors. The Batture region of the Lower Mississippi River Valley comprises land adjacent to the river that is not protected by the levee system, and is therefore subject to seasonal flooding with potential to influence the morphology and demographics of white‐tailed deer (Odocoileus virginianus). Using harvest records of 42,954 females and 3,588 males from 61 Batture properties in Mississippi and Louisiana, we created linear regression models of deer body development and recruitment indices to compare the influence of seasonal flooding, harvest rate, growing season weather, and agronomic forage availability during 1988–2016. Overall, deer in the Batture appeared to be more influenced by extrinsic factors than by harvest. Seasonal flooding appeared in every model and generally had stronger effects than weather or harvest variables. Flooding from 1 to 2 years prior, regardless of season, was correlated with greater female body mass, lactation rates, and antler mass of trophy males, possibly reflecting silt deposition effects on soil fertility and promotion of new understory forages. Conversely, current‐year flooding effects were invariably negative, implying direct effects of displacement. Summer flooding was concentrated during late gestation and peak parturition periods, and exhibited the potential to reduce fall lactation rates by 18%. Harvest rates correlated negatively with female body mass and had no correlation with lactation or antler mass. We detected contrasting long‐term trends of decreasing body mass and increasing harvest rate that may reflect deteriorating habitat. Similar to flooding, increased temperatures and rainfall had negative effects for the current year, whereas increased temperatures had positive effects when occurring in the previous year. Surprisingly, annual variation in the amount of soybeans planted appeared in one model only, exhibiting a small positive effect on antler mass. We hypothesize that extensive planting of soybeans in levee‐protected lands just outside the Batture maintained substantial soybean availability despite variation in the amount planted. Given the dominating influence of flooding and weather on deer physical and reproductive parameters in the Batture, these extrinsic variables should be incorporated into the interpretation of harvest data. The common practice of curtailing harvest, particularly female harvest, following years with extensive flooding is likely counterproductive unless intensive flooding occurs during summer.
... However, the replacement of cameras three times during 2.5 days, but probably no similar frequency of close visits at the control group, was a massive disturbance that could have biased nest failure (McKinnon and Bêty 2009). Thus, in the literature there is a broad consensus that the appropriate use of nest cameras does not affect hatching success of ground nesting birds (see also Sanders and Maloney 2002, Herring et al. 2011, Mallord et al. 2012, Ellis-Felege and Carroll 2012, Andes et al. 2019. ...
Hatching success is a key parameter for the evaluation of management activities for endangered bird species. Camera traps allow permanent monitoring of clutches and reduce the need for disturbance at the nest. We have been using camera traps since 2013 to monitor the breeding success and causes of failure of nests of the black-tailed godwit (Limosa limosa). 44 % of 326 nests monitored with a camera hatched, whereas 56 % failed. The main cause of failure was predation (92 %). In 132 egg predation events, the predator was identified to species level. Across all years and areas, the red fox (Vulpes vulpes) (47 %) was the main predator, followed by raccoon dog (Nyctereutes procyonoides) (29 %) and polecat (Mustela putorius) (13 %). Other predators were badger (Meles meles), beech marten (Martes foina), rat (Rattus norvegicus), marsh harrier (Circus aeruginosus), common buzzard (Buteo buteo), white-tailed eagle (Haliaeetus albicilla) and carrion crow (Corvus corone). The great majority of losses were, therefore, caused by nocturnal mammals, and this should be considered when implementing predation management to enhance hatching success.
Evidence against predation as a driving cause of population decline must be able to distinguish between different and interacting causes of loss. Predation can be blamed only if it removes individuals that might otherwise have lived. Detailed accounting of all causes of mortality of a given threatened species has been possible only since the development of the advanced technology summarised in Part IV. Control of stoats can benefit all native species generally, but their effects are usually confused with those of rats. The best evidence comes from rat-free Resolution, Secretary, and Anchor Islands, where stoats eradicated resident populations of Kākāpō (Strigops habroptilus), SI Kōkako (Callaeas cinerea), SI piopio (Turnagra capensis), S I tīeke (Phiesturnus carunculatus), kākāriki (Cyanoramphus sp.), and little spotted kiwi (Apteryx owenii). Stoats that invaded Maud Island and Orokonui fenced sanctuary wiped out formerly thriving refugee populations of saddlebacks/tīeke. Suppression of stoats on Waiheke Island has greatly increased nesting success and numbers of kākā (Nestor notabilis). Ferrets are deadly to larger birds, including breeding adult kiwi, weka (Gallirallus australis) and accessible seabird colonies, but are poor climbers and have never reached the most valuable islands. Weasels are generally small and now rare, but were very destructive to small prey on first arrival.
Birds and their nests are vulnerable to predation during the breeding season. Many birds have evolved nest placement strategies that minimize risk such as concealing nests in vegetation, or nesting in inaccessible cavities or on cliffs. Some ground-nesting species choose open areas where vegetative concealment or physical protection is minimal. These species may benefit from the ability to visually detect predators approaching the nest, affording them more time to perform evasive or distracting behaviors. We studied the nesting behavior of piping plovers (Charadrius melodus) on Fire Island, New York from 2015–2020 to determine if the area visible from the nest (i.e., ‘viewshed’) affected nest site selection. We calculated viewsheds at nests and random points and evaluated nest site selection using logistic regression modelling. Piping plovers selected nest sites with a greater view of predators than would be expected if nest site selection was random relative to viewshed. The inclusion of viewshed improved the predictive ability of a previous nest site selection model that was based on habitat characteristics present on the landscape in 2015, but its influence weakened as ecological succession progressed. Topographic variation was the predominant visual obstruction source at plover nest sites compared to vegetation height. Viewshed may play a role in nest site selection in other ground-nesting birds, and thus is an important factor to consider in the development of habitat management strategies and in understanding the evolution of behavior.
Aim
The goal of this work was to investigate whether the community of avian nest predators shifts from nocturnal to diurnal with changes in latitude. This hypothesis was formulated 70 years ago, under the rationale that longer day length during the bird breeding season at high latitudes increases opportunities for visual predators. Based on other studies investigating the identity of nest predators, we also considered variation in the habitat and nest height.
Location
Global.
Time Period
1994–2020.
Major Taxa Studied
Birds and their nest predators.
Methods
We reviewed studies that report the results of nest monitoring by video or photograph camera and collected data on the identity of nest predators. We then used the activity pattern of the predator species as a proxy to estimate whether predation events were nocturnal or diurnal. We used multivariate logistic and ordinal regressions to investigate whether the probability that nest predators are nocturnal changes with latitude and habitat.
Results
We found that both habitat and latitude explain variation in the circadian type of nest predators. In open habitats, nest predation was more often due to diurnal predators at high latitudes and nocturnal predators near the equator. In forests, on the other hand, nocturnal predator activity patterns were more common closer to the poles.
Main Conclusions
Using meta-analytical methods, we show that predator activity varies across habitats and latitude leading to markedly different consequences of predation for prey. These findings suggest that small-scale environmental factors such as habitat type can strongly affect and even neutralise larger-scale, ecological patterns. We speculate that day length might act along with other biotic and abiotic factors to shape the timing of nest predation in birds.
The Azores holds the largest population of Cory's shearwater Calonectris borealis (Cory, 1881) (Aves, Procellariiformes) in the world. Apart from a few mammal-free islets, the bulk of the population breeds in coastal areas on the main human-inhabited islands, where several non-native predators have been introduced. Throughout the entire year of the 2019 breeding season, we used motion-triggered cameras and regularly visited three colonies of Cory's shearwater to identify nest predators and the factors affecting nest predation. A total of 292,624 photos were obtained, of which 97.7% were of Cory’s shearwaters, 1.7% of non-target species (e.g. other birds, rabbits) and 0.52% of potential predators. Of the monitored nests, 25.7% were predated (n = 9), mainly by black rats (n = 8), but also by cats (n = 1). The relative abundance of black rats in the nests was the main factor explaining nest mortality. This variable was significantly and negatively related with the daily survival rate of Cory’s shearwater nestlings. Identification of the main nest predators is crucial for the management and conservation of native bird populations, particularly on oceanic islands, which harbour an important number of threatened and endemic species.
Nest defense behavior helps ground-nesting birds improve their breeding success. Among such behaviors, injury feigning behavior (IFB) is one of the better ways to attract predators and protect birds' nests. IFB is generally associated with shorebirds
in general and plovers in particular, however, through field observation, it has been found this behavior is also exhibited in bunting species when they facing the risk of predation. We attempt to explore the detailed description of this behavior in buntings and the factors that affect this behavior. Based on video-recordings of the nest defense behavior by the ground-nesting bird Godlewski's bunting (Emberiza godlewskii) against
nest invaders, we explored the characteristic of IFB and differences in nest defense behavior during their brooding seasons. The results showed that female buntings had
a distinct IFB: the wings of buntings incited within 60°–90° of the body, ran and called rapidly, pretending to be injured and unable to fly. The nest stage had significant and extremely significant effects on IFB and movement distance (MD), respectively. And
IFB was more likely to occur in brooding (34.62%) than incubation period (16.42%). This indicates that there are significant differences in the IFB of buntings at different breeding stages.
Concern about declining populations of bird species that breed in the grasslands and other habitats of North America has spurred extensive research on factors that may affect their reproductive success. Understanding the causes of nest failure and reduced productivity is critical for the development of conservation strategies to sustain or increase bird populations. Since the mid-1990s, advances in miniature video cameras and recording equipment have provided researchers with improved tools for monitoring active nests and for studying the behavior and ecology of nesting birds. This volume highlights information gained from such research on a variety of avian taxa in several different ecosystems. The use of video surveillance systems has provided important insights into poorly understood aspects of breeding-bird biology, including hatching, fledging, diurnal and nocturnal activity, nest-predator identification, predator-prey interactions, and cause-specific rates of nest loss. Contributions in this volume offer fresh perspectives for bird conservation and management as well as for theoretical issues not well studied in many bird species.
Predation is one of the most important extrinsic factors acting upon animal populations and is a strong selective force in the evolution of form and function. Understanding the impact of predation on bird population dynamics is crucial for understanding the predation pressure of bird populations and implementing conservation strategies, especially for threatened or endemic bird species. In this paper, we sorted the predation events in the wild Crested Ibis population in Yangxian County, Shaanxi Province, from 1981 to 2021 and in the reintroduced Crested Ibis population in Ningshan from 2008 to 2021. With the use of age‐classified Leslie matrix models to simulate Crested Ibis populations under different predation pressures, the random population growth rate was estimated, and the impact of predation on population dynamics was evaluated. The results showed that snakes and raptors were the main predators of Crested Ibis in the wild and reintroduced populations, and the number of dead individuals was unevenly distributed within the three age classes in both the wild population (df=2, χ2=13.236, P<0.05) and reintroduced population (df=2, χ2=49.273, P<0.01). Predation caused a reduction in the potential annual population growth rate of 2.37% (CI: 2.29~2.45%) in the wild population and 2.88% (CI: 2.82~2.94%) in the reintroduced population. The overall average growth rates of the wild and reintroduced populations derived from population model simulations were 12.84% and 18.13%, respectively, which suggested that the wild and reintroduced populations was increasing under the current predation pressure and that the impact of predation on the population was acceptable and sustainable. This article is protected by copyright. All rights reserved.
Seit mehreren Jahrzehnten nehmen die Bestandszahlen von Bodenbrütern europaweit ab, ein Prozess, der hauptsächlich auf die Intensivierung der Landwirtschaft zurückzuführen ist. In diesem Zusammenhang könnte aber auch die zunehmende Prädation von Raubsäugern (Carnivora, Mammalia) eine wichtige Rolle spielen. Ziel dieser Studie war die Bewertung und Einschätzung des Prädationspotentials ausgewählter Raubsäugerarten auf Bodenbrüter im brandenburgischen Vogelschutzgebiet "Mittlere Havelniederung". Von Mai 2015 bis Juni 2017 wurde die Raumnutzung verschiedener Raubsäugerarten mittels Kamerafallen und einer Telemetriestudie untersucht und anschließend mit den Ergebnissen einer Vogelkartierung verglichen. Ergänzt wurden die Untersuchungen mit einer Losungsanalyse der am häufigsten beobachteten Raubsäugerarten Waschbär (Procyon lotor) und Rotfuchs (Vulpes vulpes). Waschbären wiesen eine hohe Standorttreue sowie eine hohe Präferenz für Gewässer und Feuchtgebiete auf, während Rotfüchse eine hohe intraspezifische Variabilität in Bezug auf ihre Habitatnutzung sowie ein hohes Abwanderungsverhalten zeigten. Die Ergebnisse lassen außerdem ein hohes Prädationspotential des Waschbären auf Wasservögel vermuten, während der Einfluss auf Wiesenbrüter geringer zu sein scheint. Diese scheinen den höchsten Prädationsdruck durch den Rotfuchs zu erfahren. Die Nahrungsanalysen bestätigen diese Ergebnisse und spiegeln auch räumliche Bewegungsmuster beider Arten wieder. Diese Studie liefert als eine der europaweit ersten Studien empirische Belege für ein starkes indirektes und direktes Prädationspotential des Waschbären insbesondere auf Wasservögel. Zudem hebt diese Studie die Notwendigkeit einer differenzierten Betrachtung potenzieller Auswirkungen von Raubsäugern auf Bodenbrüter hervor und gibt einen Hinweis darauf, dass das Prädationspotential einer Raubsäugerart eng mit der Strukturvielfalt eines Lebensraums und somit mit der Intensität der landwirtschaftlichen Bewirtschaftung zusammenhängt.
Waterbird populations have declined around the world as a result of anthropogenic impacts from habitat loss and degradation, direct mortality, reproductive failure, and disturbance from humans and non-native and domestic animals. Specialist species are particularly at risk from changing environmental conditions and disturbances compared to generalist species. Plovers, lapwings, terns, and other waterbird species in the Order Charadriiformes nest on the ground, near water, and in exposed areas with little vegetative cover. As a result of their specialized breeding ecology and habitat requirements, nests of these species are therefore highly vulnerable to animal predation, flooding due to rainfall and hydrologic fluctuations, and disturbance from humans and domestic animals. Different social, economic, and political situations among world regions present distinct opportunities and challenges for implementing species conservation. In this study, I explore breeding ecology and conservation of threatened ground-nesting waterbirds in two different systems: 1) Piping Plovers Charadius melodus that breed on lakeshore beaches in the Great Lakes region of the United States, and 2) a community of six species, including River Tern Sterna aurantia, River Lapwing Vanellus duvaucelii, Great Thick-knee Esacus recurvirostris, Indian Thick-knee Burhinus indicus, Small Pratincole Glareola lactea, and Little Ringed Plover Charadrius dubius, that nest on river sand and gravel bars in the Mekong River basin in Cambodia. First, I examine factors affecting nest survival and renesting, and compare in situ and ex situ management scenarios to evaluate the potential efficacy of egg salvage as a means to augment the Great Lakes Piping Plover population. Second, I investigate factors affecting nest and chick survival of riverine birds in Cambodia, and evaluate the effectiveness of a direct payment nest protection program to improve reproductive success. Third, I examine factors affecting multi-scale habitat selection, and the consequences of habitat selection on reproductive success of riverine birds in Cambodia. This study provides valuable new information that will aid ongoing conservation efforts for threatened ground-nesting waterbirds such as the Piping Plover in North America and riverine birds in Southeast Asia. This work also has implications for conservation of threatened species more broadly.
The claim that the clutch size of three species of raptor-the wedge-tailed eagle (Aquila audax), little eagle (Hieraaetus morphnoides) and brown goshawk (Accipiter fasciatus)-increased following the introduction and spread of the rabbit (Oryctolagus cuniculus) in Western Australia was tested by comparing historical data contained in oological collections for all 24 Australian diurnal raptors and eight owls over three time-periods: before introduction of the rabbit, during the heyday of the rabbit, and after successful broad-scale control. No significant changes were found in clutch size of the little eagle either in Western Australia or more-southerly Australia in general. Clutch size of the wedge-tailed eagle, brown goshawk and whistling kite (Haliastur sphenurus) decreased significantly after rabbit control. Clutches of two eggs were more common for the wedge-tailed eagle and those of three and four eggs were more prevalent for the brown goshawk when rabbits were uncontrolled than when controlled. These changes were not due to a shift in laying date, suggesting instead an adaptive response to changes in food availability.
Nest predation studies frequently use eggs such as Japanese Quail (Coturnix japonica) to identify potential predators of Neotropical migrants' eggs, but such eggs may be too large or thick-shelled to identify the full complement of potential predators. We compared predation events and predators of Japanese Quail and smaller House Sparrow (Passer domesticus) eggs in paired, camera-monitored ground nests within edges and interiors of 40 mixed-hardwood forest stands in central Massachusetts. House Sparrow eggs were depredated significantly more than Japanese Quail eggs at both forest edges and interiors. Eleven potential predator species disturbed nests, six of which were confirmed as predators. Our use of House Sparrow eggs revealed predation by eastern chipmunks (Tamias striatus) and Black-capped Chickadee (Poecile atricapillus), but not by white-footed mice (Peromyscus leucopus), the most abundant small mammal species in all 40 stands. Neither predator species composition (as detected by camera) nor the frequency of nest predation differed between forest edge and interior. We conclude that the egg type used in artificial nest studies affects both the predation rates and the predator species detected.
Wetland birds on 11 rivers of the Upper Waitaki Basin, South Island, New Zealand were surveyed annually between 1991 - 1994. Diversity, minimum abundance and density of birds were compared. In total 26 species of wetland birds were recorded. Minimum estimated river bird numbers were: 3566 Black-backed Gulls (Larus dominicanus), 3302 Black-fronted Terns (Sterna albostriata), 3260 Banded Dotterels (Charadrius bicinctus), 793 Black-billed Gulls (Larus bulleri), 789 Wrybills (Anarhynchus frontalis), 788 South Island Pied Oystercatchers (Haematopus ostralegus), 421 Pied Stilts (Himantopus himantopus), 85 Black Stilts (Himantopus novaezelandiae), 51 Caspian Terns (Hydroprogne caspia), and 3680 waterfowl and cormorants. Densities of birds ranged from 0.17 birds ha-1 on the Pukaki River to 0.95 birds ha-1 on the Lower Ohau River. The Cass, Lower Ohau, Godley, Tekapo and Ahuriri Rivers had higher densities of one or more species than the Upper Ohau and/or Pukaki Rivers. Densities of Black-fronted Terns, Black Stilts, Pied Stilts and Caspian Terns were negatively correlated with altitude, and in general birds preferred river sections with low or moderate flows, and low or moderate vegetation cover. Eight of the 11 rivers surveyed had more than 1 % of estimated total populations of one or more of three globally vulnerable or endangered species, and in combination rivers of the Upper Waitaki Basin support almost all known Black Stilts, 15% of all Wrybills and 32 % of all Black-fronted Terns. We suggest that the Upper Waitaki Basin may now provide half of all remaining suitable braided river bird habitat in New Zealand.
1. The levels of disturbance experienced by birds in the UK are difficult to estimate but the available evidence suggests that they could be considerable, with significant implications for bird conservation. This paper addresses three sources of disturbance to birds in the UK: from recreational pursuits; developments (construction and operation); and hunting. 2. Legislative requirements to take account of disturbance impacts are increasing but there has been little research to provide a sound scientific basis for impact assessment. A review of studies of the effects of disturbance on birds between 1970 and the present reveals considerable scope for improvement in the way in which results of research are applied. Disturbance effects (e.g. local site movements) and disturbance impacts (where a population is affected) are often confused. 3. Three example studies are reviewed which may point the way forward. The first takes a multivariate approach to assess the influence of disturbance on the use of sites by birds; the second takes an experimental approach by manipulating the source of disturbance; the third takes a modelling approach to establish metapopulation impacts of disturbance. 4. From this analysis, an outline of research priorities at local, regional and flyway scales is proposed.
Change in rate of nest predation due to environmental modification is considered a major cause of population decline of many bird species. Our ability to adequately understand and effectively manage this effect is limited by our ability to identify the relative roles of individual nest predators. This is because nest predation is seldom witnessed despite its high frequency. We describe and evaluate an inexpensive photographic technique for identifying nest predators at active nests. Each camera unit (A30), using a magnetic reed switch attached to a supplementary egg. A total of 51 nests of New Holland honeyeaters (Phylidonyris novaehollandiae) was monitored with the equipment. Of these, 39 were preyed upon. Predation was never witnessed, but predators were captured on film for 72% of nests at which predation occurred.
Automatic cameras triggered by infrared beams were used to identify animals visiting artificial groundnests in north Queensland rainforest. In 1992-93 six cameras and nests were established at four sites ranging from 340 to 840m in elevation, and a total of 279 identifiable photographs of nest visitors were recorded. White-tailed rats (Uromys caudimaculatus) comprised 74% of all photographs and were the most frequent visitor at five of six nests. Bush rats (Rattus fuscipes) were second in frequency (17%), with other small mammals (Rattus leucopus, Melomys cervinipes, Perameles nasuta), birds (Ailuroedus melanotis, Pitta versicolor) and reptiles (Varanus varius) each accounting for less than 2% of nest visits. Omnivorous rodents comprised the large majority (96%) of visits and may be significant predators on nests of some ground-nesting birds in Australian tropical rainforest.
The claim that the clutch size of three species of raptor-the wedge-tailed eagle (Aquila audax), little
eagle (Hieraaetus morphnoides) and brown goshawk (Accipiter fasciatus)-increased following the
introduction and spread of the rabbit (Oryctolagus cuniculus) in Western Australia was tested by
comparing historical data contained in oological collections for all 24 Australian diurnal raptors and
eight owls over three time-periods: before introduction of the rabbit, during the heyday of the rabbit,
and after successful broad-scale control. No significant changes were found in clutch size of the little
eagle either in Western Australia or more-southerly Australia in general. Clutch size of the wedge-tailed
eagle, brown goshawk and whistling kite (Haliastur sphenurus) decreased significantly after rabbit
control. Clutches of two eggs were more common for the wedge-tailed eagle and those of three and
four eggs were more prevalent for the brown goshawk when rabbits were uncontrolled than when
controlled. These changes were not due to a shift in laying date, suggesting instead an adaptive response
to changes in food availability.
Nest predation studies frequently use eggs such as Japanese Quail (Coturnix japonica) to identify potential predators of Neotropical migrants' eggs, but such eggs may be too large or thick-shelled to identify the full complement of potential predators. We compared predation events and predators of Japanese Quail and smaller House Sparrow (Passer domesticus) eggs in paired, camera-monitored ground nests within edges and interiors of 40 mixed-hardwood forest stands in central Massachusetts. House Sparrow eggs were depredated significantly more than Japanese Quail eggs at both forest edges and interiors. Eleven potential predator species disturbed nests, six of which were confirmed as predators. Our use of House Sparrow eggs revealed predation by eastern chipmunks (Tamias striatus) and Black-capped Chickadee (Poecile atricapillus), but not by white-footed mice (Peromyscus leucopus), the most abundant small mammal species in all 40 stands. Neither predator species composition (as detected by camera) nor the frequency of nest predation differed between forest edge and interior. We conclude that the egg type used in artificial nest studies affects both the predation rates and the predator species detected.
The accidental introduction of the brown treesnake (Boiga irregularis) on Guam around 1950 induced a cascade of extirpations that may be unprecedented among historical extinction events in taxonomic scope and severity. Birds, bats, and reptiles were affected, and by 1990 most forested areas on Guam retained only three native vertebrates, all of which were small lizards. Of the hypotheses to account for the severity of this extinction event, we find some support for the importance of lack of coevolution between introduced predator and prey, avail-ability of alternate prey, extraordinary predatory capabilities of the snake, and vulnerabilities of the Guam ecosystem. In addition, there were important interac-tions among these factors, especially the presence of introduced prey (possessing coevolutionary experience) that were thus able to maintain their populations and provide alternate prey to the introduced predator while it was driving the native prey species to extinction. This complex of vulnerabilities is common on oceanic islands. 1 The US government has the right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper.
Because the demand for liver donor organs continues to surpass organ availability, efforts to optimize patient selection and donor allocation procedures remained at the forefront of the literature in 1997. Innovative strategies such as split liver transplantation and the use of what were once considered marginal donors have proven to be successful in expanding the donor pool. However, these novel approaches cannot solve the problem of organ shortage without continued efforts at increasing donation rates. Further investigation into reduction of immunosuppression continues as increased success with liver transplantation surgery and improved patient survival have resulted in new problems with long-term medication side effects. Viral diseases such as cytomegalovirus infection and recurrent hepatitis remain a major cause of morbidity and mortality in liver transplant patients. However, long-term survival rates following transplantation for patients with hepatitis C appear excellent. Innovative treatment of patients with hepatitis B using hepatitis B immunoglobulin and nucleoside analogue agents continues to offer hope for improved survival rates in this patient group.
We monitored the behaviour of 62 radio-collared ferrets and 25 radio-collared cats in dry, tussock grassland habitat in New Zealand's South Island. The total home range of adult male ferrets (102 ± 58 ha, mean ± 1 s.d.) was marginally greater than that of females (76 ± 48 ha), and average 90 ± 55 ha. Male ferret core ranges (27 ± 15 ha) were larger than those of females (16 ± 8 ha). Adult cat home ranges were similar between sexes, and were larger and more variable than those of ferrets (225 ± 209 ha). Core range size of cats was similar between sexes and averaged 54 ± 24 ha. The upper 95% confidence limits of the mean home range lengths of adult ferrets and cats were 2.7 km and 5.1 km, respectively, indicating the width of buffer zones where predator control should be extended to protect the boundaries of areas targeted for predator control in dry, tussock grasslands. Although core areas were mostly discrete, home ranges were distributed randomly, and animals that shared space neither avoided nor attracted each other. Little evidence of territoriality may be related to high densities of primary prey. Too few cats were monitored to determine territoriality. Ferrets used at least 9.4 ± 3.2 dens, and cats used 11.5 ± 3.0 dens during the study. Although 71% of dens were used only once, some were used up to nine times. Day time resting by ferrets was mostly solitary. If transmission of bovine Tb occurs between adult ferrets, simultaneous sharing of dens during the day is unlikely to be a significant mode of transmission in this habitat. We were unable to determine the extent of den sharing by cats. Cats occupied den sites with more shrubs and rocks compared with ferrets. Predator control stations in dry tussock grassland habitat may therefore be more effective at killing cats than ferrets if placed in shrubby, rocky areas.
The nesting success of pied stilt Himantopus h. leucocephalus and the endangered black stilt H. novaezealandiae was studied in New Zealand. Black stilts had a breeding success of <1%, compared with >8% for pied stilts. Predation by feral mammals was the main cause of nest failure for both species, but the impact was greater on black stilts. Several factors made black stilts vulnerable, particularly their nesting along stream banks that were often frequented by predators; pied stilts nested in swamps where predators were few. black stilt chicks took up to 2 wk longer to fledge and their foraging patterns made them more vulnerable than pied stilt chicks. Other factors that possibly increased predation risk of black stilts include nesting at times of high predator activity, solitary nesting, high site fidelity, ineffective distraction displays, and lack of a disruptive camouflage pattern in adults.-from Author
Using gut samples, faecal analysis, records of prey brought home by house cats and uneaten remains in the field, the diet of domestic and feral Felis catus is examined. In descending order of frequency, mammals, birds and (especially below latitude 35o) reptiles predominate. Cat predation on islands, where bird prey is proportionally more significant, often has an adverse impact on native species. Diet is discussed in terms of sex and age differences; seasonal variations; and prey availability. The impacts of cats on farmyard rats; on wild rabbits Oryctolagus cuniculus, voles and other rodents; on game species; on bird populations on continents; and on island wildlife, are all discussed. -S.J.Yates
Banded Dotterels (Charadrius bicinctus bicinctus) exhibit a variety of seasonal movement patterns ranging from sedentary behaviour, through migration within New Zealand, to trans-Tasman migration. From 1985 to 1990 the Ornithological Society of New Zealand (OSNZ) studied the regional patterns of movement of Banded Dotterels which had been colour-banded on the breeding grounds. Sight-recoveries indicated that most birds in inland regions of the southern half of the South Island migrated to Australia, but coastal breeding birds in the South Island were mostly sedentary. Inland birds north of Canterbury mostly moved within New Zealand, particularly to harbours in the North Island but with regionally specific patterns - Westland birds mainly to Farewell Spit, Marlborough birds to the northern North Island and Farewell Spit, southern North Island birds either locally or to the Auckland region, and most Hawkes Bay and Volcanic Plateau birds to Bay of Plenty and Auckland. Breeding habitat modified this pattern; coastal birds were mainly sedentary, whereas birds on nearby inland riverbeds were migratory. Migration patterns are discussed in terms of advantages and disadvantages of different wintering options.
With the increasing popularity of remote photography in wildlife research, a large variety of equipment and methods is available to researchers. To evaluate advantages and disadvantages of using various types of equipment for different study objectives, we reviewed 107 papers that used either time-lapse or animal-triggered photography to study vertebrates in the field. Remote photography was used primarily to study avian nest predation, feeding ecology, and nesting behavior; additional applications included determining activity patterns, presence-absence monitoring, and estimating population parameters. Using time-lapse equipment is most appropriate when animals occur frequently in the photographic frame, the activity of interest occurs repeatedly, or no distinct event occurs to trigger a camera. In contrast, animal-triggered (light or mechanically triggered) systems are appropriate when events occur infrequently or unpredictably and there is a great likelihood that a trigger will be activated. Remote photography can be less time consuming, costly, and invasive than traditional research methods for many applications. However, researchers should be prepared to invest time and money troubleshooting problems with remote camera equipment, be aware of potential effects of equipment on animal behavior, and recognize the limitations of data collected with remote photography equipment.
We describe an electronic trigger coupled to an automatic camera for identifying predators at artificial nests. The system is portable, correctly exposes the predator during day or night for clear photographs, has close-up capabilities, automatic advance, and an external power supply for extended field use.
Sections of nine rivers in the Upper Waitaki Basin were surveyed between 1991 and 1994 and these surveys were compared with counts completed in 1962, 1965 and 1968. A systematic account of 27 wetland birds is given. Densities (number of birds km-1) of birds were compared between the two periods. Species that increased in density were mainly common generalists, whereas species that decreased in density were endemic river breeding specialists. Densities of Wrybills (Anarbyncbus frontalis), Spur-wing Plovers (Vanellus miles), Canada Geese (Branta canadensis), and Grey Teal (Anas gracilis) were higher in the 1990s than in the 1960s, whereas densities of Banded Dotterels (Charadrius bicinctus), waterfowl and shags, Black-billed Gulls (Larus bulleri), South Island Pied Oystercatchers (Haematopus ostralegus), Black-backed Gulls (L. dominicanus) and Black-fronted Terns (Sterna albostriata) were lower in at least one river in the 1990s compared to the 1960s. Estimated minimum populations of river birds published for the Ahuriri River (surveyed in 1982) and the Cass River (surveyed in 1979 and 1982) were usually intermediate to those recorded in equivalent 1960s and 1990s surveys. Four mechanisms that explain changes in braided river bird populations are suggested.
Breeding success and nest predation effects on the two Canarian endemic pigeons, Bolle's Laurel Pigeon Columba bollii and White-tailed Laurel Pigeon C. junoniae, were studied during 1995 in five zones of laurel forest on Tenerife Island. Nest predation was the more important cause of nesting failure of both species (88%), but principally affecting the White-tailed Laurel Pigeon. Experiments using artificial nests showed a greater predation on the ground than in trees and a lower predation in the February-March period than in June-July and September-October. The abundance of predators, estimated by bait consumption, showed a similar seasonal pattern, while fruit availability decreased over time from the first to third period. Predators identified by automatic cameras showed that Black Rat Rattus rattus was the major nest predator of both pigeons. These general patterns of nest predation affect the White-tailed Laurel Pigeon, which breeds on the ground mainly during April-July, much more than Bolle's Laurel Pigeon, which breeds in trees, especially in February-June. All seems to indicate that rats are the key factor causing the scarcity of the White-tailed Laurel Pigeon on Tenerife.
Nest predation is an important factor reducing reproductive success of many birds. However, few data are available on the relative role of different predators. This paper describes an automatic camera setup that can be used to study predation on artificial nests. Because the setup is relatively inexpensive, it should allow fieldworkers to conduct large- scale investigations of nest predation and determine its importance as a selective force in the evolution of avian reproductive strategies. MONTAJE DE CAMARAS FOTOGRJ, FICAS EN NIDOS ARTIFICIALES, PARA ESTUDIOS DE DEPREDACI)N DE HUEVOS Sinopsis.--La depredaci6n en nidos es un factor de importancia en la reducci6n delxito reproductivo de muchas aves. Sin embargo, hay pocos trabajos que documenten el rol de diferentes depredadores. Este trabajo describe el montaje de una cfimara automfitica que puede ser utilizada para estudiar la depredaci6n en nidos artificiales. Debido a que el montaje cs de bajo costo, esto debe permitirle a los investigadores, 11evar a cabo amplios estudios sobre el efecto de depredadores y sus implicaciones en la evoluci6n de estrategias reproductivas de aves.
An intensive predator trapping programme was implemented in the upper Waitaki Basin, New Zealand from October 1997 to January 1998. The aim of the programme was to prevent increased predation on vulnerable braided river fauna following decline in rabbits due to rabbit haemorrhagic disease (RHD). Fourteen sites were trapped using a standardised method, and trap catch results provided a relative index of predator abundance. In 101 650 trapnights, 1067 hedgehogs, 328 ferrets, 196 cats, 96 rats and 69 stoats were caught. Predator guilds varied among sites and guild composition tended to change through time; for example, stoat and rat catch rates increased. Cat and ferret catch rates increased in the last month of trapping, which suggested that juvenile dispersal and immigration by adult predators from surrounding areas were high. This study provides baseline information on predator abundance and predator guilds in the upper Waitaki Basin against which future trapping programmes can be compared, in order to assess changes in predator populations since the introduction of RHD.
Population viability analysis was used to assess the survival prospects of mohua (Mohoua ochrocephala) populations of varying sizes, with different breeding strategies and suffering predation episodes at varying frequencies, from the South Island of New Zealand. Mohua populations in which most pairs attempted to raise two broods of chicks each year were more vulnerable to episodic stoat (Mustela erminea) predation than were populations in which pairs attempted to raise only one brood. However, those populations in which most pairs raised two broods had a much better ability to recover following predation. High stoat numbers every year would lead to the extinction of mohua populations regardless of their size and breeding strategy, but one‐brood populations would decline more slowly. If stoat populations were high only once every 5 years (the likely natural rate in South Island beech forests), small populations, and populations in which most pairs raised only one brood a year, would have very low survival prospects, but two‐brood populations of more than about 40 pairs would have good survival prospects. Reduction in stoat densities, particularly in years when their numbers are high, is likely to have a substantial positive effect on mohua populations.
Prior to human settlement the endemic New Zealand avifauna evolved in the absence of mammalian predators. Subsequently mustelids, rodents and feral cats have become established and frequently prey on birds and nests. It has been suggested that, because of their evolutionary history, the endemic birds are especially susceptible to such predators. In this paper predation by mustelids and rodents on the eggs and nestlings of eight species of native bird is compared with that on five species of introduced European passerine inhabiting the same lowland forest.
Final outcomes were known for 101 nests of native birds and 48 nests of introduced birds found during three breeding seasons. There was no significant difference between the two groups in frequency of predation. Native birds lost 70-1% of their nests to predators and introduced birds 64-6%. Most predations occurred during the egg stage. Clutch size did not influence frequency of predation, but brood size did for Fantails and introduced birds. Stoats and weasels were responsible for 77-9% of predations on native birds and 77-4% on introduced birds; corresponding percentages for rodents (principally ship rats) were 14-7% and 19-4%. Mustelids destroyed proportionately more nests with chicks than with eggs, whereas rodents did the reverse. Predation on both groups of birds was not influenced by their nesting habitat, the species of tree used for nesting, or the height and position of the nest. The vulnerability to introduced predators of native New Zealand birds is discussed in relation to the historical declines of many species, and also their life-history patterns.
Artificial nest experiments have been used in approximately 80 recent studies to identify a wide range of factors influencing reproductive success of birds. Despite the same factors being examined in different studies, few consistent patterns have emerged from these experiments. Analysis of reproductive success at artificial and natural nests reveals that reproductive success measured with use of artificial nests is frequently underestimated. In addition, several studies suggest that different species of predators may be differentially attracted to the two types of nest. These results call the utility of artificial nests into question as a tool for elucidating factors influencing the success of natural nests. Analysis of the methodology used in artificial nest experiments reveals that in general there is poor correspondence between the appearance of experimental setups and the natural systems they attempt to model. If future experiments with artificial nests are to contribute to theory, the quality of experiments must improve and the assumptions underlying the artificial approach must be tested. Collecting this information will be relatively simple compared with the time-consuming task of experimenting with natural nests. Until these data are collected, conclusions about nesting ecology derived from the use of artificial nest experiments should be treated as preliminary.
Dead Sooty Shearwater, Puffinus griseus, chicks and adults were collected from seven colonies on South Island, New Zealand in the 1993–96 breeding seasons. An estimated 97% of 118 deaths were from predation. Thirty-four definite predator bite pairs were identified on 27 carcasses. Twenty-one (78%) of the carcasses had bite pairs with intercanine distances < 9.5 mm which suggests that Stoats (Mustela erminea) were the principal predators. One chick was killed by a feral House Cat (Felis catus), and it is likely that feral Ferrets (M. furo) were responsible for a proportion of the deaths. Nearly three quarters of definite Stoat bite pairs were identified in the head region. The analyses of bite marks offers cheap and statistically reliable identification of predators provided carcasses are collected fresh and flesh is removed to examine tooth punctures in bone.
Common sandpipers Actitis hypoleucos breeding around the Ladybower Reservoir in the Peak District National Park, England, are disturbed by anglers and other visitors, so that they take flight about 29% more than they would if undisturbed; they frequently are forced to encroach on their neighbours' territories, causing far more fighting than done by nearby riverine birds. They take flight from an approaching human at 27 m, but when guarding their chicks react (‘alarm’) at 75 m; anglers may stand as close as 25 m apart, emphasising the potential for disturbance. Disturbance from anglers is high at the start of the breeding season, and continues, though slackening, throughout, whereas casual disturbance from other visitors is very erratic. Along the north shore of the reservoir, common sandpipers avoid using the favoured angling beaches, whereas on the south shore they retreat into the conifer plantations. The consequence is a reduction in the size of the breeding population, but breeding success is unaffected.
Generalized sedimentation models have been developed from a review of more than sixty recent papers on modern and ancient braided-stream deposits. Braided rivers consist of a series of broad, shallow channels and bars, with elevated areas active only during floods, and dry islands. There are three main bar types; longitudinal, comprising crudely bedded gravel sheets; transverse to linguoid, consisting of sand or gravel and formed by downstream avalanche-face progradation; and point or side bars, formed by bedform coalescence and chute and swale development in areas of low energy. Important sediment-forming processes include bar formation, channel-floor dune migration, low-water accretion and overbank sedimentation.
We created a stochastic habitat-based population model to compare the relative effectiveness of potential conservation strategies to increase the endangered Great Lakes population of piping plovers. Initial model parameters were based on an extensive 14-year dataset obtained by annual studies of breeding pairs in Michigan and 6 years of observations of color-marked individuals. Cumulative persistence probability curves and population trends were compared for scenarios with all possible combinations of the following: (1) empirical, medium and high site specific probabilities of reproductive success and (2) empirical, medium and high numbers of available breeding territories. Sites were also categorized according to land ownership to determine if long-term preservation of publicly owned lands is sufficient for population recovery under any of the scenarios. Only scenarios in which both reproduction and habitat availability were high and all ownership classes were included resulted in a model population that persisted for 100 years and was likely to reach the US Fish and Wildlife Service current population recovery goal (100 breeding pairs) for Michigan. The model was most sensitive to survival rates of adults and more sensitive to changes in reproductive parameters than to number of breeding sites or territories. Model results suggest that intensive measures to increase productivity alone are not sufficient for population recovery; increases in nesting densities or total number of available territories are also likely necessary. Given uncertainties about nesting densities possible at specific breeding sites, preservation of presently unoccupied habitat throughout the Great Lakes region and management of this habitat to encourage breeding by plovers are recommended. Use of techniques to augment the breeding population in conjunction with protection of habitat and reproduction may be warranted.
Kokako Callaeas cinerea wilsoni (Callaeidae) populations are declining in unmanaged primary forests of the North Island, New Zealand. An 8-year experiment to determine the cause of decline was undertaken by controlling introduced browsing and predatory mammal pests in two forest areas, then monitoring pest abundance, kokako chick output and adult density in the managed forests and an unmanaged non-treatment block. Treatments were switched between the unmanaged and one of the managed areas after 3–4 years. Reduction of pests, especially brushtail possums Trichosurus vulpecula and ship rats Rattus rattus, to very low levels resulted in significant increases in kokako chick output and adult density in all three study populations. This was due primarily to increased success of nesting attempts, which then increased the number of pairs attempting to breed, initially as newly recruited young females formed pairs with residual single males. The `adaptive management' approach of using routine large-scale pest control in a co-ordinated experiment to directly test the pest-limitation hypothesis enabled researchers and managers to investigate the cause of decline and to increase populations simultaneously. Predation is a more immediate cause of current kokako declines than competition. Management to recover vulnerable kokako populations should aim to reduce possums and ship rats to very low levels (<1% trap catch for possums; <1% tracking rate for ship rats, using particular indexing techniques) at the onset of the kokako nesting season, for several consecutive years.
Thesis (Ph.D.)--University of Otago, 1982. Bibliography: leaves 273-286.
New Zealand, like many other islands, has suffered extinctions of native species and successful introductions of exotic species. It has been uncertain whether the introductions caused the extinctions or whether the extinctions permitted the introductions. On New Zealand's Hauraki Gulf islands, which are unusual in their near lack of introduced mammalian predators and complete lack of mammalian browsers, exotic bird species abundant in mainland New Zealand forest and reaching these islands are virtually absent from unmodified forest. Exotic bird species disappeared from Cuvier Island's forest after elimination of mammalian predators and browsers. Hence extinctions of native species were not due to competition from introduced species but to other factors (such as mammalian predators and habitat alteration). Only after decimation of native species and forest alteration by browsing mammals could exotic birds invade forest.
Food and feeding behaviour of the Black-fronted Tern, Chlidonias hybrida albostriatus
- C Lalas
Lalas, C., 1977. Food and feeding behaviour of the Black-fronted
Tern, Chlidonias hybrida albostriatus. Unpublished MSc thesis,
University of Otago, Dunedin.
Diet, nesting behaviour, and home range size of the European hedgehog in the braided rivers of the Mackenzie Basin
- K A Moss
Moss, K.A., 1999. Diet, nesting behaviour, and home range size of the
European hedgehog in the braided rivers of the Mackenzie Basin,
New Zealand. Unpublished MSc thesis. University of Canterbury,
Christchurch, New Zealand.
Norway rat Handbook of New Zealand Mammals
- P J Moors
Moors, P.J., 1990. Norway rat. In: King, C.M. (Ed.), Handbook of New Zealand Mammals. Oxford University Press, Auckland, New Zealand, pp. 192–206.
Shorebirds under threat
- Walsby
Walsby, J., 1997. Shorebirds under threat. New Zealand Geographic
36, 96-112.