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Diagram of the bullet-camera we used to identify the species and the number of eggs in each nest box. We placed the camera at the entrance hole of each box, viewing and recording the images on the video camera. This procedure was fast and effective, resulting in minimal disturbance to nest box occupants (image credit Daryl King)
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Introduced species pose a major threat to biodiversity across the globe. Understanding the impact of introduced species is critical for effective management. Many species around the world are reliant on tree cavities, and competition for these resources can be intense: threatening the survival of native species. Through the establishment of 225 nes...
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Restoration of altered or degraded habitats is often a key component in the conservation plan of native aquatic species, but introduced species may influence the response of the native community to restoration. Recent habitat restoration of the middle section of the Provo River in central Utah, USA, provided an opportunity to evaluate the effect of...
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... Habitat destruction and capture for the pet trade are considered the most important contributing factors to parrots' population declines worldwide, including in Africa (Olah et al. 2016). Populations of parrots are also threatened by infectious diseases, persecution and introduced species (Warburton and Perrin 2006;Grarock et al. 2013;Martin et al. 2014;Berkunsky et al. 2017;Fogell et al. 2018). Given the large number of threatened species, parrots have received insufficient research attention (Christie et al. 2021), and little is known about the status and basic biology of many wild populations. ...
Lovebirds (genus Agapornis of family Psittaculidae) are a group of small, colourful parrot species endemic to
sub-Saharan Africa and Madagascar, two-thirds of which are considered to have declining populations. Effective
conservation efforts are hampered by a lack of information, particularly for species occurring in regions that have
received little research attention. We combined expert knowledge with a review of the primary and grey literature
to identify key knowledge gaps and priority conservation actions for this group of birds. Published studies were
found to be largely concentrated on lovebird populations in southern Africa and, to a lesser extent in East Africa,
and therefore mostly concern members of the ‘white eye-ring’ clade. Some species, such as the Black-collared
Lovebird Agapornis swindernianus, remain very poorly studied, with a lack of even basic information such as
georeferenced occurrence records. Several lovebird species were historically taken from the wild in large numbers
for the international pet trade, leading to population declines. Although trade in wild lovebirds has been much
reduced compared with historical levels, considerable numbers are still captured for local and international trade
without any monitoring of the wild populations. Habitat change continues to drive declines in the population and
range of some species, particularly those considered habitat specialists, such as the Nyasa Lovebird A. lilianae
and the Black-cheeked Lovebird A. nigrigenis. However, changing habitat has also driven range expansions and,
in combination with trade, has created numerous novel contact zones between formerly allopatric species, such
as between Fischer’s Lovebird A. fischeri and Yellow-collared Lovebird A. personatus. Hybridisation has been
widely reported, particularly in East Africa, and studies on the implications of this for conservation, building on
recent advances in genetic tools, are urgently needed. We call for more targeted research on lovebirds to inform
assessments of their population trends, to understand the drivers of these trends, and to highlight opportunities to
leverage existing data and new research tools to advance knowledge to support conservation in this group of birds.
... In Australia, the introduced common myna occupies modified diverse climates from the tropical north-east coast, down the east coast to temperate environments and into Mediterranean climates, and reaches its highest abundance in human-dominated landscapes [14]. Despite its large invasive range [15], the impact of the common myna on native species has only been shown in a small part of its range in Australia and only on a few species [16,17]. The extent to which the common myna impacts nesting opportunities for many of the native birds the myna co-exists with across its Australian range remains a significant knowledge gap. ...
... Boxes had an entrance hole that was 65 mm in diameter. We chose these boxes as they are suitable for the common myna and several native species [16]. Nest boxes were placed at heights between three and five meters and at least 10 m from the closest box. ...
... In long-invaded areas, we observed more nesting attempts by common myna than all other birds combined. The presence of the common myna alone was not enough to deter native species from nesting, but competitive exclusion could arise when nest box occupancy reaches higher levels [36,37], as has been observed in areas where common mynas are more abundant [16]. The higher number of nesting attempts in long-invaded areas may also reflect fewer natural cavity availability given that longer-invaded areas in N.S.W. tended to be in larger cities. ...
Simple Summary
We aimed to investigate how an invasive cavity-breeding bird, the common (Indian) myna, and a native nest predator, the common brushtail possum, influence urban nest box use by native birds in Queensland and New South Wales, Australia. We quantified nest box use by invasive and native species, assessed nesting success and failure rates, and explored what environmental factors might influence nest box occupancy and nesting success. We found that the native possums were the most common nest box users and that possum occupancy of boxes was associated with higher rates of nesting failures by all bird species. More common myna nesting attempts were observed in areas where mynas have been established longer. We found no evidence of a significant negative impact by the common myna on other birds in our study locations, which may be partly due to the low rates of use of our nest boxes by native birds. Nevertheless, better nest box design and guidelines for setting them up are needed if we aim to provide more nesting opportunities for native birds to replace the decline in big old cavity trees.
Abstract
Many bird species in Australia require tree hollows for breeding. However, assessing the benefits of urban nest boxes to native birds requires frequent monitoring that allows to assess nesting success. To better understand the benefits of nest boxes for native birds, we examined the impact of local habitat characteristics, invasive species (common myna, Acridotheres tristis), and native mammalian predators on urban nest box use and nesting success of native birds. We installed 216 nest boxes across nine locations in southeastern Australia (S.E. Queensland and northern New South Wales) in both long-invaded sites (invaded before 1970) and more recently invaded sites (after 1990). We monitored all boxes weekly over two breeding seasons. We recorded seven bird species and three mammal species using the nest boxes. Weekly box occupancy by all species averaged 8% of all boxes, with the species most frequently recorded in the nest boxes being the common brushtail possum (Trichosurus vulpecula), a native cavity user and nest predator. We recorded 137 nesting attempts in the boxes across all bird species. The most frequent nesting species were the invasive alien common mynas (72 nesting attempts). We recorded an average nesting failure rate of 53.3% for all bird species. We did not record any common mynas evicting other nesting birds, and found that several native species used the same box after the common myna completed its nesting. We recorded native possums in 92% of the boxes, and possum occupancy of boxes per site was negatively correlated with bird nesting success (p = 0.021). These results suggest that when boxes are accessible to invasive species and native predators, they are unlikely to significantly improve nesting opportunities for native birds. To ensure efficient use of limited conservation resources, nest boxes should be designed to target species of high conservation importance and limit other species of both predators and competitors.
... Some bird species are secondary cavity nesters, and they use nests excavated by other bird species (Rendell and Robertson 1994). They include several invasive bird species, such as Common Myna Acridotheres tristis, European Starlings Sturnus vulgaris and Rose-ringed Parakeets (Koenig 2003;Grarock et al. 2013;Charter et al. 2016). Although the latter is regarded as invasive in South Africa, relatively little research has been conducted on its breeding biology, including factors influencing their nest selection and reproductive success. ...
... Another explanation for the artificial nest box non-uptake could be that the breeding sites have enough natural nest cavities for parakeets to breed. The Common Myna was reported to affect the breeding success of the Eastern Rosella Platycercus eximius and Crimson Rosella Platycercus elegans by taking over their nest boxes in Canberra, Australia (Grarock et al. 2013). Charter et al. (2016) in Tel Aviv, Israel, found that Common Mynas occupied the majority (62-74%) of artificial nest boxes compared with Rose-ringed Parakeets (5-14%). ...
The Rose-ringed Parakeet Psittacula krameri has established feral populations in South African suburban areas. However, the information on the breeding biology of parakeets remains poorly documented in the country. We assessed parakeets' breeding status and behaviour by locating their roost and breeding sites in Durban, eThekwini Metropole, KwaZulu-Natal province. We also placed artificial nest boxes to determine the occupancy of parakeets or other bird species. We identified 39 parakeet breeding sites with a total of 72 nests. There were no significant differences between the number of active parakeet nests in the first (n = 53 nests) and second breeding seasons (n = 59). Rose-ringed Parakeets used four tree species for nesting, with the white milkwood Sideroxylon inerme used the most (71%). Only East African lowland honey bees Apis mellifera scutellata and Common Mynas Acridotheres tristis used the artificial nest boxes. Parakeet fledgings recorded ranged between one and three per nest, and their numbers differed significantly between seasons. The number of fledglings was not influenced by any of the tree variables measured and distance or location. The distance between the parakeets' roosting and breeding sites ranged from 1.43 to 5.0 km. Our study provides essential data for an overall management strategy, including eradication programs for this species in South Africa.
... Factors including latitude (Green 1997;, community assemblage (Lodge 1993), biotic resistance (e.g. Elton 1958; Jeschke 2014), and competition (e.g., Grarock et al. 2013) may play roles in the ability of introduced parrots to become established. ...
... Once an alien species is present within a community, its establishment may be hindered by competition with native birds for similar resources. One such resource is nesting sites, which could be a limiting factor for establishment, especially for cavity-nesting birds (Grarock et al. 2013;Martens and Woog 2017). With the exception of a few species, psittaciforms are cavity nesters (Juniper and Parr 2010), and it is thought that native cavity-nesting species suffer the most impact from the presence of naturalized parrots . ...
... Both the Common Starling and Common Myna have had reported impacts on native parrots, with the most direct impact being increased competition for nesting sites Tidemann 1997a, 1997b;Holdsworth 2006;Haythorpe 2013;). However, the impacts of such species are not consistent across habitats, and most studies have been restricted to the southeast of Australia in a small part of the invasive range of these species (Sol et al. 2011;Grarock et al. 2012Grarock et al. , 2013. Generally, competition between invasive and native cavity-nesting species is likely to be highest for species that are close in size and share preferences for nest sites (Diamond and Ross 2020;Rogers et al. 2020), providing insight into the potential impacts for future invasive species. ...
... En este contexto, las cajas-nido ofrecen una solución viable para paliar este déficit de oquedades (e.g., Jokimäki, 1999). En ocasiones, no obstante, su eficiencia ha sido puesta en duda debido a las bajas tasas de ocupación o la ocupación de las cajas por especies no objetivo (Grarock et al., 2013, Williams et al., 2013. En términos w y globales, el uso de cajas-nido en medios urbanizados mejora la presencia de especies de aves autóctonas y contribuye a aumentar la diversidad (Jokimäki, 1999). ...
Las cajas-nido constituyen una herramienta muy útil para el desarrollo de diversos estudios
en aves, pues permiten el diseño experimental y la comparación de muestras sometidas a
distintos tratamientos o localizaciones. Igualmente, son útiles para la conservación de aves
en hábitats con muy poco arbolado maduro, como ocurre en muchos parques urbanos.
Con el fin de impulsar la biodiversidad en el ámbito urbano, la Sociedad de Ciencias Aranzadi inició en 2018 el proyecto Hirilife, entre cuyas acciones estaba la colocación de cajas nido para aves paseriformes insectívoras en arbolado en calles, paseos y parques urbanos de la ciudad de San Sebastián. Este artículo se presenta con el fin de (1) determinar la tasa de ocupación de estas cajas-nido; y (2) explorar los factores que condicionan esta ocupación, con el fin de establecer, a futuro, una guía de buenas prácticas orientada a optimizar su colocación. A lo largo de la primavera de 2020 se revisaron 202 cajas en total, de las 220 que se habían colocado. Se ocuparon un total de 91 (45%). La tasa de ocupación, no obstante, varió significativamente entre zonas. Las cajas en las que se pudo determinar la especie fueron ocupadas por dos especies de páridos: el herrerillo común Cyanistes caeruleus y el carbonero común Parus major. Se observa una dominancia del carbonero común (31 versus 10 cajas; el resto se corresponde con las que no se pudo determinar la especie).
Según los modelos las cajas son ocupadas con más probabilidad cuando se sitúan en entornos con una gran cantidad de hábitat natural.
Abstract: Nest-boxes constitute a very useful tool in ornithological studies, since they allow the development of experimental designs and permit comparisons to be made between samples
subjected to different treatments and locations. Moreover, they are also useful for bird
conservation in habitats with low amounts of mature trees, as occurs in many urban parks.
The ‘Hirilife’ project, developed by the Aranzadi Sciences Society, was launched in 2018
with the aim of promoting biodiversity in urban areas. This project included actions oriented
to install and monitor nest-boxes for insectivorous passerine birds in the streets, promenades and parks of the city of San Sebastian. As a result, in this article we (1) describe the nest-box occupation rate, and (2) examine those factors that determine this rate, with the aim of drawing up a good practice guide to optimize the installation of new nestboxes in the future. During the spring of 2020, 202 nest-boxes were surveyed. Overall, 91 were occupied (45%). The occupation rate, however, varied substantially between zones.
The nest-boxes were occupied by two species: the blue tit Cyanistes caeruleus and the
great tit Parus major. The latter species was dominant (31 versus 10 nest-boxes). According
to the model of nest-box, these were more likely to be occupied when they were situated
in areas close to/surrounded by a high amount of natural habitat.
... Consequently, colonizing parks and urban edges would likely increase spatial overlap and therefore competitive interactions with native species (Diquelou and Griffin, 2020). Direct observational evidence of aggressive competition for breeding resources has not yet been found in a large-scale nest-box study Rogers, 2018), although it has been inferred from patterns of nest box occupancy in remnant urban bushland in earlier work (Grarock et al., 2013;Pell and Tidemann, 1997). It has recently been shown that mynas are extremely aggressive around natural hollows (Rogers et al., 2020) and excluding them increases the breeding success of native species on islands (Blanvillain et al., 2020). ...
Theory suggests that overcrowding and increased competition in urban environments might be detrimental to individual condition in avian populations. Unfavourable conditions could be compounded by changes in dietary niche with additional consequences for individual quality of urban birds. We analysed the isotopic signatures, signal coloration, body condition, parasitic loads (feather mites and coccidia), and immune responsiveness of 191 adult common (Indian) mynas (Acridotheres tristis) captured in 19 localities with differing levels of urbanization. The isotopic signature of myna feathers differed across low and high urbanized habitats, with a reduced isotopic niche breadth found in highly urbanized birds. This suggests that birds in high urban environments may occupy a smaller foraging niche to the one of less urbanized birds. In addition, higher degrees of urbanization were associated with a decrease in carotenoid-based coloration, higher ectoparasite loads and higher immune responsiveness. This pattern of results suggests that the health status of mynas from more urbanized environments was poorer than mynas from less modified habitats. Our findings are consistent with the theory that large proportions of individual birds that would otherwise die under natural conditions survive due to prevailing top-down and bottom-up ecological processes in cities. Detrimental urban ecological conditions and search for more favourable, less crowded habitats offers the first reasonable explanation for why an ecological invader like the common myna continues to spread within its global invasive range.
... Earlier work (Grarock et al. 2014a) investigating common myna impacts along an urban gradient in Canberra found that the common myna in combination with habitat change was a driver of changes in bird communities, but that work did not report the impact of noisy miners. The low abundance of mynas we observed across some sites, especially in Queensland, relative to other parts of its range (Grarock et al. 2013), highlights important variation in the common myna's success across the continent. Nevertheless, the higher average abundance of noisy miners compared to common mynas across our urban gradients means that the baseline levels of aggression by native noisy miners need to be taken into account when assessing impacts of non-native species (Mac Nally et al. 2012;Haythorpe et al. 2014). ...
... In contrast, the common myna in experimental studies quantifying aggressive interactions around food sources has shown that mynas are less aggressive than many urban adapted native species (Sol et al. 2012). Most of the impact of common myna is restricted to competition for natural tree hollows (Pell and Tidemann 1997a;Grarock et al. 2013). Regardless of the relative impact of each species on bird communities, both mynas and miners show preferences for more open habitats so efforts to maintain or restore habitat should mitigate the impact of these two species. ...
... Patterns of common myna abundance were highly variable across source-front gradients. The pattern of increasing common myna abundance with increasing urbanization is consistent with other studies from across its range (Sol et al. 2012;Grarock et al. 2013). Common myna can reach high densities in cities, and in some parts of its invasive range, it is one of the most common urban birds (Grarock et al. 2012). ...
The extent to which native species utilize urban environments depends on species responses to multiple threatening processes. Here, we aimed to quantify changes in bird communities in response to changing habitat structure, invasive species and aggressive native species. We conducted surveys in two independently invaded regions with similar patterns of urban development. The study regions were New South Wales (NSW) and Queensland (QLD), Australia. We observed 127 species in NSW and 144 species in QLD. Most species (NSW 83 and QLD 84) are urban adapters making use of some or all urban sub-environments. Urban avoiders, species only found in remnant vegetation, were the second largest group (urban avoiders: NSW 23 and QLD 31). We found the lowest richness in the most urban sites (urban exploiters: NSW 10 and QLD 15). Using generalized linear mixed models, we found a non-significant relationship between species richness and the abundance of aggressive species like the common myna and noisy miners, Manorina melanocephala, but a significant positive correlation with the percentage of shrub cover at a site. As there is a gradual loss of species with increasing urbanization, retaining higher complexity in vegetation structure in urban areas will support large numbers of species and could help mitigate the potential impacts of aggressive urban-adapted species and habitat loss.
... We used vertical nest boxes made of plywood (400 (H) x 170 (W) x 170 (D) mm) with an entry hole diameter of 65 mm (Nest Boxes Australia, Loganholme 4129 Australia). The nest box design was informed by former successful nest box studies examining interactions between Mynas and native parrots (Orchan et al. 2012;Grarock et al. 2013). Each box was fitted with a 75 cm external perch located 3 cm under the entrance and an internal ladder was carved out of the internal wall allowing easier access for the parrots. ...
... Across three breeding seasons, more than half of parrot nests failed, mainly caused by hatch failure. To our knowledge, there has been only one other breeding analysis of parrots and Mynas, and that study found comparative levels of clutch failure in parrots in highly urbanised areas of Canberra as we did here (55% of the clutches did not produce nestlings) (Grarock et al. 2013). We currently do not know why so many parrot eggs fail to hatch. ...
... In conclusion, future research is needed to confirm the possibility that urban reproduction is challenging for native parrots. Research needs to focus on quantifying reproductive success of parrots in non-urban environments and in natural tree hollows to provide a comparison for urban nest box studies like this one and that of Grarock et al. (2013). Another focus needs to be on lifetime success of mynas and parrots in order to determine whether species differences in annual reproductive success found here and in Grarock and colleagues' work is compensated for by longer lifetime reproduction. ...
Australian cavity-nesting birds in urban habitats can encounter strong competition for nesting cavities. This results from the shortage of old large hollow-bearing trees in urban areas and because cities often host a suite of alien birds, including cavity-nesters. However, it is unclear whether some behavioural differences are involved with access to nesting cavities. We aimed to examine parental nest attendance, nest disturbance and breeding success in native parrots and the most common invasive urban bird in Australia, the Common Myna, Acridotheres tristis. We installed 78 experimental nest boxes in Newcastle, the second largest city in New South Wales, Australia, to compare native parrots and Mynas. We found that despite occupying nest boxes equally, native parrots had significantly lower breeding success, lost more clutches to hatch failure, exhibited lower levels of parental nest attendance, and encountered higher levels of nest disturbance than the alien Myna. These findings provide important insight into the breeding success of native and alien secondary cavity-nesting birds in cities. Evaluating the effectiveness of urban nest boxes will help guide future research and management aimed at optimising nest box design for maintaining native cavity breeders.
... Australia has a uniquely high percentage of cavity-nesting birds, with at least 115 species of birds (15% of all Australian bird species), including eight species of invasive birds, using hollows for nesting or roosting (Gibbons & Lindenmayer, 2002). Cavitynesting species are of conservation concern as the loss of large hollow-bearing trees from modified habitats (Koch, Munks, & Spencer, 2009;Koch & Woehler, 2007;Le Roux, Ikin, Lindenmayer, Manning, & Gibbons, 2014) and the presence of invasive species (Lindenmayer et al., 2017) reduces nesting opportunities in urban habitats (Grarock, Lindenmayer, Wood, & Tidemann, 2013). ...
... However, interspecific competition in these studies has mostly been inferred from spatial segregation in nests site locations (Grarock et al., 2013;Pell & Tidemann, 1997), or co-occurrence around potential nest sites (Davis, Major, & Taylor, 2013). ...
... Previous work has shown that the common myna is not more aggressive than native species around food resources (Haythorpe et al., 2012;Lowe, Taylor, & Major, 2011;Sol et al., 2012). In a study of nest box use in Canberra, Grarock et al. (2013) found spatial segregation between common myna and native bird species and attributed that pattern in part to competition, yet direct aggressive interactions were not explicitly quantified. In Sydney, Lowe et al. (2011) also found that mynas occupied few natural tree hollows in remnant forest patches and suggested mynas were no more aggressive than native species. ...
Interaction networks among native and invasive species in a community can inform both invasion impacts and applied management of invasive species. The intensity of aggressive interactions may be related to the overlap in species’ ecological niche and functional traits, especially in cavity‐breeding species, that often compete for limited nesting sites. Australia is home to over 100 native and introduced cavity‐nesting species, including several invasive species that are widespread globally, such as the common myna Acridotheres tristis. Here, we aimed to test the extent to which shared functional traits inform the intensity of aggression between cavity‐nesting birds.
We quantified the outcomes of aggressive interactions between birds in large hollow‐bearing trees in SE Queensland, Australia. We examined whether more similarly sized birds interacted more frequently, whether larger species won aggressive interactions more often, and whether cavity‐breeding species with similar preferences for nesting sites (breeding‐niche space) interacted more frequently.
We recorded a total of 410 aggressive interactions and 48 interacting bird species around tree hollows, including 20 cavity‐nesting bird species. These interactions were dominated by the invasive common myna, the native noisy miner (a non‐cavity‐breeder) and the native rainbow lorikeet Trichoglossus moluccanus, but the common myna won the largest total number of interspecific interactions. On average, larger birds won aggressive interactions more frequently, yet there were some important exceptions to this finding; the common myna (113 ± 30 g) won 26 of the 29 interactions against the larger native rainbow lorikeet (126 ± 44 g). Importantly, species with more similar nest‐site preferences were observed aggressively interacting more frequently.
Synthesis and applications. The impact of the invasive common myna was higher‐site preferences. Control efforts for the myna should focus on birds that nest in natural tree hollows. An analysis of shared traits by managers could be used to help identify how many local species would benefit from common myna control in a given area and test if further behavioural studies of common myna are warranted.
... No introduced pest species that are known to use natural and artificial hollows in human-disturbed landscapes (e.g. Common Myna A. tristis, Black rat Rattus rattus; Harper et al. 2005;Lindenmayer et al. 2009;Grarock et al. 2013) were recorded visiting chainsaw hollows. These results are consistent with other studies undertaken within timber production forest landscapes in southeastern Australia, where endemic hollow-dependent mammals and birds have been observed to use chainsaw hollows, while no exotic species were recorded (Rueegger 2017;Lumsden et al. 2016). ...
Anthropogenic disturbance has resulted in a global reduction in the abundance of mature, hollow‐bearing trees. Nest boxes have long been used to provide supplementary shelter sites in revegetated and regenerating landscapes, but limitations in their effectiveness when offsetting the loss of mature trees has led to increased interest in novel designs of artificial hollows. For example, mechanically excavating cavities into the trunk or branches of trees. However, the effectiveness of artificial hollows in attracting wildlife to visit small‐ or medium‐sized, growing trees in human‐disturbed landscapes has received little attention. In this study, we installed chainsaw hollows that were designed for small, hollow‐dependent mammals and birds into the trunks of live medium‐sized trees. We conducted a before‐after control‐impact (BACI) experiment using passive camera traps to monitor changes in visitations by wildlife to (a) mature hollow‐bearing trees, (b) developing trees without hollows (i.e. control trees), and (c) developing trees with newly installed chainsaw hollows. We found that, compared to large hollow‐bearing trees and control trees, the developing trees that were selected for chainsaw hollow construction showed the greatest visitation rates by hollow‐dependent wildlife (i.e., number of visits) during the ‘post‐impact’ surveys. Our results suggest that chainsaw hollows designed to replicate the external physical characteristics of natural tree hollows could be effective in attracting target hollow‐dependent fauna to developing trees in regenerating and revegetated landscapes. Further studies are required to compare the effectiveness of natural hollows, chainsaw hollows and nest boxes when deployed in a range of human‐disturbed landscapes.
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