Article

Scavenging of Ruffed Grouse in the Appalachians: Influences and Implications

September 2002
Wildlife Society Bulletin 30(3):853-860

Authors:

Virginia Tech

Scavenging is often neglected as a source of bias when determining causes of mortality and collecting mortality-related habitat information. The use of mortality-sensing radio-transmitters has greatly increased our understanding of animal survival. However, the potential of lag-time in recovery of carcasses and subsequent determinations of cause of death are seldom addressed. Motion created by feeding predators and scavengers can delay pulse switchover and prolong recovery. We determined the influence of temperature, forest stand type, overhead cover, and carcass condition on scavenging rates, displacement patterns, and habitat sampling biases at perceived kill sites for ruffed grouse (Bonasa umbellus). We documented carcass disturbance, scavenger species, and displacement distances for 64 carcasses. Mammalian scavengers disturbed 42 of 64 grouse carcasses. Scavenger species identified included mice (Peromyscus spp.), flying squirrel (Glaucomys spp.), cottontail rabbit (Sylvilagus floridanus), Virginia opossum (Didelphis virginiana), raccoon (Procyon lotor), long-tailed weasel (Mustela frentata), bobcat (Lynx rufus), eastern coyote (Canis latrans), and common raven (Corvus corax). Air temperature and carcass condition were the dominant factors associated with scavenger disturbance of grouse carcasses. Mammal scavenging activity increased during warmer temperatures, and mock avian kills were scavenged more frequently than whole carcasses. Potential overestimation of mammalian-caused mortality may result from scavenging, especially when ambient air temperature is warmer and carcasses have been previously fed upon.

The role of scavenging in the predator community of Białowieża Primeval Forest (E Poland)

Thesis

Full-text available

Jan 2004

Nuria Selva

Scavenging affects persistence of avian carcasses resulting from window collisions in an urban landscape

Article

Full-text available

Jun 2012

Collisions with windows remain an important human-related threat to bird survival in urban landscapes. Accurately estimating the magnitude of avian mortality at windows is difficult and may be influenced by many sources of error, such as scavenging of carcasses. Failure to account for removal of carcasses by scavengers can bias estimates of window mortality. We tested the hypothesis that carcass survival depends on local habitat factors known to influence scavenger behavior. Scavenger activity on bird carcasses was documented at 20 buildings in an urban landscape in northwestern Illinois for 1 week during each season of a year. Known-fate models were used to relate carcass survival to local habitat composition and to evaluate temporal variation in survival. We also documented species of scavengers and the timing of scavenging using motion-triggered cameras. Daily carcass survival was greater in winter than during spring, summer, and fall. Survival was related negatively to canopy cover (trees and shrubs within a 50-m buffer) and window area, and positively to pavement cover. Using an exponential model of survival time, estimated mean time of survival of carcasses (t± SE) was 82.9 ± 11.7 d for winter and 11.8 ± 7.2 d for other seasons. Raccoons (Procyon lotor) scavenged more carcasses than other species. Our results suggest that (1) carcass survival times may be short at locations with preferred habitats of known scavengers and predictable sources of food, and (2) knowledge of scavenger distribution and activity can inform predictive models of persistence. In studies of bird-window collisions, the influence of scavenger bias can be minimized by maintaining short time intervals between carcass searches. Search intervals can be inferred by estimating the number of days that a carcass should persist at a site, which can be calculated using predicted daily survival probabilities of carcasses at study buildings.

Survival of sharp-tailed grouse Tympanuchus phasianellus chicks and hens in a fragmented prairie landscape

Article

Jan 2009

Doug Manzer

We studied survival and probable causes of mortality for plains sharp-tailed grouse Tympanuchus phasianellus jamesi chicks up to 30 days of age, and for hens during the reproductive period in Alberta, Canada, during 1999-2001. We used the Kaplan-Meier function for estimating survival for >1 radio-marked chick in the same brood and a bootstrapping technique to calculate standard errors while accounting for censored data. Chick survival was 47% over two years (95% CI: 29-64%) with 81% of mortalities occurring during the first 15 days. Predation accounted for 72% of chick mortalities with mammals taking the largest portion. Chick survival was similar when compared between landscapes with <35% vs ≥35% crop and sparsely covered grassland (8 km2). Hen survival was 53% (95% CI: 44-63%) during the reproductive period over three years. Most hen mortalities were from predation (96%), with mammals accounting for the largest portion followed by raptors. Hen survival was similar in landscapes (8 km2) with <35% crop and sparsely covered grasslands compared with those in areas with ≥35%. Our study helps clarify values of two critical vital rates, i.e. early chick survival and hen survival over the reproductive period.

Survival and Detectability Bias of Avian Fence Collision Surveys in Sagebrush Steppe

Article

Feb 2011
J WILDLIFE MANAGE

We used female ring-necked pheasant (Phasianus colchicus) carcasses as surrogates for greater sage-grouse (Centrocercus urophasianus) to study factors influencing survival and detection bias associated with avian fence collision surveys in southern Idaho, USA, during spring 2009. We randomly placed 50 pheasant carcasses on each of 2 study areas, estimated detection probability during fence-line surveys, and monitored survival and retention of carcasses and their associated sign over a 31-day period. Survival modeling suggested site and habitat features had little impact on carcass survival, and constant survival models were most supported by the data. Model averaged carcass daily survival probability was low on both study areas and ranged from 0.776 to 0.812. Survival of all carcass sign varied strongly by location, and the top sign survival model included a site effect parameter. Model averaged daily survival probability for collision sign on the 2 study sites ranged from 0.863 to 0.988 and varied between sites. Logistic regression modeling indicated detection probability of carcasses during fence-line surveys for avian collision victims was influenced by habitat type and microsite shrub height at the carcass location. Carcasses located in big sagebrush (Artemisia tridentata) habitats were detected at a lower rate (0.36) than carcasses in little (A. arbuscula) and black sagebrush (A. nova) habitats (0.71). Increasing shrub height at the carcass location from the little sagebrush mean of 16.5 cm to the big sagebrush mean of 36.0 cm reduced detection probability by approximately 30%. Avian fence collision surveys in sagebrush-steppe habitats should be conducted at ≤2-week sampling intervals to reduce the impact of survival bias on collision rate estimates. Two-week sampling intervals may be too long in areas with low carcass and sign survival, therefore survival rates should be estimated on all study areas to determine the appropriate sampling interval duration. Researchers should be aware of the effects of local vegetation on detection probabilities, and methods to correct detection probabilities based on collision site attributes should be applied to ensure more accurate collision rate estimates. Additionally, caution should be used when aggregating or comparing uncorrected collision data from areas with differing vegetation, as detection probabilities are likely different between sites. © 2011 The Wildlife Society.

EFFECTS OF SCAVENGING ON ASSUMPTIONS OF MORTALITY ANALYSES OF RADIO-MARKED GAMEBIRDS

Article

Dec 2019

Survival estimation is critical to studies of wildlife population biology and recent model developments allow for temporal covariates on mortality risk. To test model assumptions that scavengers do not influence either perceived mortality cause or location, we placed 24 radio-marked Chukar (Alectoris chukar) carcasses randomly over gradients of grassland habitat conditions in eastern Montana in both April 2017 and July 2018, and monitored scavenging activity at intervals relevant to gamebird telemetry studies. High rates of scavenging (12.5–78%, depending on season and relocation interval) suggest that scavenging activity could confound determination of cause-specific mortality but that its influence varies with season. Scavenging activity did not significantly influence perceived mortality locations regardless of season or local habitat conditions with a relocation interval of 3 d (8% of carcasses moved), but mortality locations may be biased over longer periods (50% of carcasses moved in 7-d period), particularly in warm seasons or regions.

Scavenging by snowshoe hares (Lepus americanus) in the Yukon, Canada

Article

Jun 2018

Winter Scavenging Rates Under Power Lines in the Karoo, South Africa

Article

Full-text available

Apr 2015
S AFR J WILDL RES

IMPACTS OF FENCES ON GREATER SAGE-GROUSE IN IDAHO: COLLISION, MITIGATION, AND SPATIAL ECOLOGY

Article

Kerry P. Reese

Factors affecting carcass use by a guild of scavengers in European temperate woodland

Article

Full-text available

Dec 2005
CAN J ZOOL

Although facultative scavenging is very common, little is known about the factors governing carrion acquisition by vertebrates. We examined the influence of carcass characteristics, carcass state, and weather conditions on carrion use by main scavengers. Carcasses (N = 214, mainly ungulates) of various origins (predation, natural deaths, harvest) were monitored by systematic inspections (N = 1784) in Białowieża Forest (Poland). Common raven (Corvus corax L., 1758), red fox (Vulpes vulpes (L., 1758)), and European pine marten (Martes martes (L., 1758)) mainly used the prey remains of gray wolves (Canis lupus L., 1758). The kills of predators were the preferred carrion, rather than dead ungulates. Common ravens, common buzzards (Buteo buteo (L., 1758)), white-tailed eagles (Haliaeetus albicilla (L., 1758)), and domestic dogs scavenged more frequently on carcasses in open habitats. Carcasses located in the forest were the most available to European pine martens, jays (Garrulus glandarius (L., 1758)), and wild boar (Sus scrofa L., 1758). The common tendency was to increase scavenging when temperature decreased, except for raccoon dogs (Nyctereutes procyonoides (Gray 1834)). As snow depth increased, jays and great tits (Parus major L., 1758) increased scavenging. We suggest that carrion use by scavengers is not random, but a complex process mediated by extrinsic factors and by behavioural adaptations of scavengers.

Variation in the taphonomic effect of scavengers in semi-arid Australia linked to rainfall and the El Nino Southern Oscillation (ENSO)

Article

Mar 2006
INT J OSTEOARCHAEOL

Scavenging is one of the primary taphonomic processes shaping the final composition of fossil faunal assemblages. The taphonomic effect of scavengers is variable and must be understood in the context of the causes of that variation. In this study, we investigated relationships between the El Niño Southern Oscillation (ENSO), variable rainfall and scavenging on 20–40 kg mammal carcasses in semi-arid New South Wales over four years. Following periods of above-average rainfall (coincident with the La Niña phase of the ENSO), there was an increased availability of non-carrion food and scavenging activity was moderate. Following below-average rainfall (coincident with the El Niño phase of the ENSO), foraging options diminished, leading to a greater importance of carrion in the diet of scavengers and a resultant increase in carcass disturbance, transport and destruction by scavengers. Feral pigs (Sus scrofa) and red foxes (Vulpes vulpes) were the most taphonomically significant scavengers in the study. Australian ravens (Corvus coronoides) and wedge-tailed eagles (Aquila audax) were active scavengers throughout the period of the study, but had little impact on bone survival. Lace monitors (Varanus varius) also fed mostly on soft tissue and were only present seasonally. We found that climate variability in the form of short-term oscillation can result in significant variation in the impact of scavengers on carcasses and may be an important consideration when evaluating site formation scenarios and biases in fossil faunal assemblages. Copyright © 2006 John Wiley & Sons, Ltd.

Survival of a polymorphic species in seasonally snow-covered forests

Preprint

Full-text available

May 2023

Color polymorphism is an adaptive strategy in which a species exhibits multiple color phenotypes in a population. Often times, phenotypes are variably suited to different environmental conditions which may buffer the population against variable conditions. Modern climate change is creating novel selective pressures for many species, especially in winter habitats. Few studies have quantified the benefits of polymorphism for allowing species to cope with climate-induced environmental change. We investigated how color polymorphism mediates selective pressures in ruffed grouse Bonasa umbellus, a widespread and winter-adapted bird species of North American forests. Ruffed grouse display phenotypic variation in plumage color, ranging from red to gray. Over five winter seasons (2015-2022), we monitored weather conditions, habitat use, and weekly survival for 94 ruffed grouse to test whether individuals had lower survival when grouse were phenotypically mismatched with snow cover (e.g., a gray bird on a snowless landscape or a red bird in snow). Grouse phenotypically mismatched with snow cover had lower survival, but only when winter survival rates were lowest. During winters of lower overall survival, red grouse exhibited higher survival during snow-free periods, whereas gray grouse had higher survival when snow was present. We also found that open habitat negatively impacted survival, regardless of color. While the effect of phenotypic mismatch was variable among years, it was a stronger predictor of winter survival than land cover features, suggesting that snow is an important habitat feature mediating overwinter survival. Our work offers an advancement in understanding how environmental variability affects geographic variation in and maintenance of multiple color phenotypes in seasonally-snow covered environments. Our finding that interactions between color morph and snow cover are important for conferring winter survival provides further evidence that color polymorphism may serve as a buffer against rapidly changing conditions and a pathway for persistence of polymorphic species.

Uncovering Forensic Taphonomic Agents: Animal Scavenging in the European Context

Article

Full-text available

Apr 2022

Animal scavenging by vertebrates can significantly alter human bodies and their deposition site. For instance, vertebrate animals can cause postmortem modification to a body, alter perimortem trauma, influence decomposition rates, disarticulate and scatter body parts or evidence, and affect the identification of the deceased. Animal scavenging is a relatively common occurrence in forensic investigations. Even so, studies on the subject are scattered and rare, with most focussing on geographical areas outside of Europe. For that reason, we intend to collate the literature to provide an account of forensically relevant vertebrate scavengers in Europe, their impacts on human remains, and their implications for forensic investigations. Here, we provide an overview of forensic aspects where the knowledge of animal scavenging is crucial, as well as an account of potential scavengers of human remains in Europe and their typical alterations to soft tissue and, in particular, to bones. In addition, we are the first to provide a guide for forensic practitioners to identify the presence of vertebrate scavenging and subsequently inform outdoor search strategies for affected human remains.

Lesser Prairie-Chicken Survival in Varying Densities of Energy Development

Article

Full-text available

Jun 2021

Anthropogenic features increasingly affect ecological processes with increasing human demand for natural resources. Such effects also have the potential to vary depending on the sex and age of an individual because of inherent behavioral and life experience differences. For the lesser prairie-chicken (Tympanuchus pallidicinctus), studies on male survival are limited because most previous research has been focused on females. To better understand patterns of lesser prairie-chicken survival in habitat with varying levels of anthropogenic infrastructure associated with oil and natural gas development, we monitored survival of 178 radio-tagged male and female lesser prairie-chickens in eastern New Mexico, USA, from 2013 to 2015. We examined the relationships of shrub cover, proximity to and density of anthropogenic features (i.e., utility poles), displacement of natural vegetation by anthropogenic features (i.e., area of roads and well pads), and individual demographics (i.e., sex, age) with lesser prairie-chicken survival. Furthermore, we categorized the probable cause of mortality and examined its relationship with oil and gas development intensity (indexed by utility pole density) within 1,425 m of an individual's mortality site or final observed location. We predicted that survival would be lower for individuals exposed to greater levels of anthropogenic features, and that males and subadults would be more negatively affected than females and adults because of increased exposure to predators during the lekking season and naiveté. Relationships between survival and utility pole density, sex, and age were supported in our top-ranked models, whereas models including other anthropogenic and natural features (i.e., roads, well pads, shrub cover) received little support. We predicted a substantial decrease in adult and subadult male survival with increasing densities of utility poles. The relationship between survival and utility pole density for females was weaker and not as clearly supported as for males. We did not find a detectable difference in utility pole counts among probable mortality causes. Our findings highlight the importance of including male lesser prairie-chickens in research and conservation planning, and the negative effect that high densities of anthropogenic features can have on lesser prairie-chicken survival.

Greater Sage-Grouse survival varies with breeding season events in West Nile virus non-outbreak years

Article

May 2021

Greater Sage-Grouse (Centrocercus urophasianus) is a species of conservation concern and is highly susceptible to mortality from West Nile virus (WNV). Culex tarsalis, a mosquito species, is the suspected primary vector for transmitting WNV to sage-grouse. We captured, radio-tagged, and monitored female sage-grouse to estimate breeding season (April 15 to September 15) survival, 2016–2017. Deceased sage-grouse were tested for active WNV; live-captured and hunter-harvested sage-grouse were tested for WNV antibody titers. Additionally, we trapped mosquitoes with CO2-baited traps 4 nights per week (542 trap nights) to estimate WNV minimum infection rate (MIR). Eight sage-grouse mortalities occurred during the WNV seasons of 2016 and 2017, 5 had recoverable tissue, and 1 of 5 tested positive for WNV infection. Survival varied temporally with sage-grouse biological seasons, not WNV seasonality. Survival was 0.68 (95% CI: 0.56–0.78; n = 74) during the reproductive season (April 1 to September 15). Mammalian predators were the leading suspected cause of mortality (40%), followed by unknown cause (25%), avian predation (15%), unknown predation (15%), and WNV (5%). These results indicate WNV was not a significant driver of adult sage-grouse survival during this study. Three sage-grouse (1.9%; 95% CI: 0.5–5.9%) contained WNV antibodies. We captured 12,472 mosquitoes of which 3,933 (32%) were C. tarsalis. The estimated WNV MIR of C. tarsalis during 2016 and 2017 was 3.3 and 1.6, respectively. Our results suggest sage-grouse in South Dakota have limited exposure to WNV, and WNV was not a significant source of sage-grouse mortality in South Dakota during 2016 and 2017. Based on our finding that a majority of sage-grouse in South Dakota are susceptible to WNV infection, WNV could potentially have an impact on the population during an epizootic event; however, when WNV is at or near-endemic levels, it appears to have little impact on sage-grouse survival.

Until It’s a regulation It’s not my fight: Complexities of a voluntary nonlead hunting ammunition program

Article

Jan 2021

Wildlife and human health are at risk of lead exposure from spent hunting ammunition. Lead exposure persists for bald eagles due to bullet fragments in game animal gut piles and unretrieved carcasses, and is also a human health risk when wild game is procured using lead ammunition. Programs encouraging the voluntary use of nonlead ammunition have become a popular approach mitigating these effects. This study explored attitudes and experiences of United States Fish and Wildlife Service (USFWS) staff implementing an outreach program encouraging deer hunters to voluntary use nonlead ammunition on 54 National Wildlife Refuges (NWRs) in the Upper Midwest, U.S. to understand factors affecting program implementation. We conducted 29 semi-structured interviews of USFWS staff along with 60 responses from an open-ended survey question. Twelve themes emerged from the data and were grouped into three broad categories: (1) challenges of dealing with complex issues, (2) importance of messengers and messages, and (3) resistance from staff. Challenges of dealing with complex issues included administrative restraint and uncertainty, scope and scale of program, human health not an agency responsibility, contextual political influences, and public-private collaborations. Importance of messengers and messages included the importance of experience, and salience of human health risk. Finally, resistance from staff included skepticism of the science and motives behind the program, competing priorities for refuge staff, differing perceptions of regulatory and voluntary approaches, cost and availability of nonlead ammunition, and disregard by some about lead ammunition and human health risks. Staff identified numerous challenges implementing the program, many of which were external factors beyond the control of the participants. Understanding the factors affecting program implementation may help guide future efforts encouraging the voluntary use of nonlead ammunition.

Shark-based tourism presents opportunities for facultative dietary shift in coral reef fish

Article

Full-text available

Aug 2019
PLOS ONE

Tourism represents an important opportunity to provide sustainable funding for many ecosystems, including marine systems. Tourism that is reliant on aggregating predator species in a specific area using food provisioning raises questions about the long-term ecological impacts to the ecosystem at large? Here, using opportunistically collected video footage, we document that 61 different species of fish across 16 families are consuming tuna flesh at two separate shark dive tourism operations in the Republic of Fiji. Of these fish, we have resolved 55 to species level. Notably, 35 (63%) of the identified species we observed consuming tuna flesh were from ostensibly non-piscivorous fishes, including four Acanthuridae species, a group primarily recognized as browsers or grazers of algae and epibenthic detritus. Our results indicate that shark diving is having a direct impact on species other than sharks and that many species are facultatively expanding their trophic niches to accommodate the hyperabundance of resources provided by ecotourism.

Mortality in Aransas-Wood Buffalo Whooping Cranes: Timing, Location, and Causes

Article

Jan 2019

The Aransas-Wood Buffalo Population (AWBP) of Whooping Cranes (Grus americana) has experienced a population growth rate of approximately 4% for multiple decades (Butler et al., 2014a; Miller et al., 1974). Population growth for long-lived species of birds is generally highly sensitive to variation in adult mortality rates (Sæther and Bakke, 2000). A population model for endangered Red-crowned Cranes (Grus japonensis) in Japan conforms to this pattern, where growth rate is most sensitive to adult mortality (Masatomi et al., 2007). Earlier analyses observed that the AWBP growth rate increased in the mid-1950s and that this increase was likely caused by reduced annual mortality rates, even while the population experienced slightly decreasing natality (Binkley and Miller, 1988; Miller et al., 1974). A more contemporary analysis of the AWBP determined that approximately 50% of variation in annual population growth could be explained by variation in annual mortality (Butler et al., 2014a). Therefore, as a vital rate, mortality is critical to the maintained growth of the AWBP.

Mortality in Aransas-Wood Buffalo Whooping Cranes: Timing, Location, and Causes

Chapter

Jan 2019

Causes and Patterns of Mortality in Lesser Prairie-chickens Tympanuchus pallidicinctus and Implications for Management

Article

Full-text available

Jun 2007

Life-history studies of prairie grouse have focused on reproductive ecology, habitat use, movement patterns and survivorship, with only cursory or anecdotal references to mortality causes, or they have been of insufficient duration or scale to infer mortality patterns. Because mortality causes and patterns affect other life-history traits, their determination adds to our over- all understanding of grouse demographics. As part of a long-term study on lesser prairie-chicken Tympanuchus pallidicinctus natural history in Okla- homa and New Mexico, we recovered 322 carcasses of radio-tagged birds captured on leks. We were able to determine the cause of death for 260 of these birds. Predation by raptors accounted for the largest number of mor- talities (91), followed by collisions with fences (86), predation by mammals (76), collisions with power lines (4), and collisions with automobiles (3). Mortality causes differed considerably between study sites and between sexes, with all collisions more frequent in Oklahoma than in New Mexico, in females than in males, and in older than in young females. Although predation is a major cause of mortality, we argue that predator control may not be effective for grouse conservation. Moreover, in cases where top predators reduce mesopredator population densities, for example those of red foxes Vulpes vulpes, indiscriminate removal of predators may hasten the decline of grouse populations. Land managers striving to conserve prairie- chickens and other grouse species should attempt to reduce or eliminate collision mortality risks in addition to efforts to improve nesting or brood- rearing habitat. Collision risks should also be evaluated for potential re- lease sites of translocated or captive-reared grouse.

Scavenging on Ungulate Carcasses in a Mountain Forest Area in Northern Italy

Article

Mar 2018

We investigated the scavenging behavior of some vertebrate species inhabiting a mountainous area of Eastern Tuscany (Italy). Fieldwork was conducted by using camera traps from July 2010 to June 2013. The red fox (Vulpes vulpes) resulted to be the main scavenger species, followed by the wolf (Canis lupus), while the wild boar (Sus scrofa) resulted to be one of the less efficient scavengers, exploiting, in groups, only two carcasses. The wolf seemed to use carcasses mostly during the summer season, while no differences in red fox seasonal use of and visit to carcasses were detected. All the wild scavenger species showed a peak of activity between dusk and dawn, during both summer and winter, likely to minimize human disturbance. The red fox used carcasses whenever available, and in most cases it also was the first species arriving on a new carcass, with a very limited searching time. This paper represents the first Italian study on carrion use by Mediterranean vertebrate communities.

Survival, Harvest, and Drumming Ecology of Ruffed Grouse in Central Maine, USA

Article

Aug 2017

Samantha Davis

Understanding population dynamics and how species interact with their environment are important components for conservation and management. Ruffed grouse (Bonasa umbellus) are a widely distributed and common game bird in North America and are a considered an important economic and cultural icon in Maine. Although they are a well-studied species, there has been little research focused on ruffed grouse population dynamics and habitat relationships in Maine. My thesis aims to improve this knowledge gap by focusing on research related to survival and harvest of ruffed grouse, as well as male ruffed grouse resource selection at breeding display sites. Ruffed grouse are generally considered abundant in Maine, but there is a lack of states specific knowledge of their survival and harvest rates to inform harvest management. To address this component we estimated seasonal and annual survival rates, harvest rates, and documented cause-specific mortality of 248 radio-marked ruffed grouse at two study areas in central Maine from 2014 –2016. We used nest survival models implemented in Program MARK to evaluate sources of spatial, temporal, and individual variation that may affect survival and harvest. Our results showed survival was lowest during the month of October and during winter, and adult ruffed grouse had a higher survival probability than juveniles throughout the year (β -0.49 ± 0.15 SE). Harvest rates were greater in a state owned Wildlife Management Area, and were lower at our study area comprised of commercially-managed private forest (β=0.72 ± 0.38 SE). Pooled across all years and study areas, the ruffed grouse harvest rate was 0.16 (95% CI = 0.14-0.18). Our results are comparable to other range-wide studies, and suggest that ruffed grouse hunting regulations in Maine produce rates of harvest that are consistent with sustainable population management. Resource selection reflects behavioral choices that species make at different levels within their environment, but the fitness consequence of these choices are not always well understood. We evaluated habitat selection at breeding display sites, and the effects on breeding behavior, of male ruffed grouse in central Maine during April and May 2015–2016. We used resource selection functions (RSFs) that took the form of generalized linear models to compare habitat characteristics at used display locations (n=72) with those at available locations (n=144), and we further assessed how selected habitat features from the RSFs were associated with three drumming display characteristics; drumming rate, and wing beat rate. We used Akaike’s Information Criterion to assess model support and selection. We found that male ruffed grouse selected drumming locations with high total stem density (β=0.52, 95% CI= 0.22-0.82), as well as high conifer stem density within 5m from the display stage (β= 0.46, 95% CI= 0.17-0.75). However we did not find that these same variables were associated with drumming behaviors, suggesting no effect of habitat selection on breeding display behavior. Understanding habitat selection and the possible fitness consequences of those selection choices will allow managers to identify areas of critical habitat needed to further benefit the species.

Effects of rangeland management on survival of female Greater Prairie‐Chickens

Article

Full-text available

Jan 2018

Identifying relationships between habitat selection and population processes is important for habitat management and wildlife conservation. For prairie-obligate species, space use and demography in extant grasslands are influenced by habitat conditions caused by rangeland management practices associated with livestock production. Greater prairie-chickens (Tympanuchus cupido) are an indicator species for native tallgrass prairie ecosystems, but populations have declined in the Flint Hills ecoregion of eastern Kansas, USA because of intensification of rangeland management practices, including annual prescribed fire and high stocking densities. Patch-burn grazing is a rotational system that provides heterogeneous habitats and can improve productivity of grassland birds, but the effects of grazing systems on habitat use or survival of greater prairie-chickens are unknown. We used 3 types of survival analyses to investigate impacts of rangeland management on female greater prairie-chickens in the central Flint Hills during 2011–2013: Kaplan–Meier models and Cox proportional hazards to examine factors affecting annual survival rates, hazard functions to assess seasonal patterns of mortality, and Andersen–Gill models to explore the links between habitat selection and cause-specific mortality risk. Females captured at properties managed with patch-burn grazing had annual survival rates (0.61 ± 0.07 SE) that were 35% higher than females on properties managed with annual burning and intensive early cattle stocking (0.45 ± 0.06). Moreover, females that selected habitats associated with intensive management had increased mortality risk and were particularly vulnerable to avian predators, whereas females that selected habitats created by patch-burn grazing experienced lower overall mortality risk but were more vulnerable to mammalian predators. Overall mortality risk was significantly reduced under patch-burn grazing management, and widespread implementation of annual spring burning and intensive early stocking is likely depressing survival of greater prairie-chickens in the Flint Hills ecoregion. Our results join a growing body of evidence that patch-burn grazing can provide higher quality grassland habitats for native wildlife species than current rangeland management associated with intensive cattle production.

Ruffed grouse population ecology in the Appalachian region

Article

Full-text available

Jan 2007

The lesser prairie-chicken in the mixed-grass prairie ecoregion of Oklahoma, Kansas, and Texas

Article

Full-text available

Jan 2016

Wolfe, D. H., L. C. Larsson, and M. A. Patten. 2016. The Lesser Prairie-Chicken in the mixed-grass prairie ecoregion of Oklahoma, Kansas, and Texas. Raton, Florida.

Chapter

Full-text available

Jan 2016

Seasonal and Sex-Biased Survival of Adult Interior Western Screech-Owls ( Megascops kennicottii macfarlanei ) in Southeast British Columbia

Article

Dec 2015

In Canada and in British Columbia, the interior Western Screech-Owl (Megascops kennicottii macfarlanei) has been assessed as a species at risk primarily as a result of loss and degradation of low-elevation riparian habitat. Few data exist on population demographics of this subspecies. We analyzed annual survival of 19 radio-tagged adult owls from 2009 through 2013 using known-fate models. Time and sex dependence in annual survival rates were examined. The best approximating models suggested that female annual survival (28%) was lower than male survival (83%). Owl survival was lowest prior to incubation and during brood rearing, times when owls are most vocal. Mortality was attributed to avian predation and road mortality. Management practices to preserve habitat during the critical breeding period are encouraged in light of this research.

Population structure of greater sage-grouse in northeastern California: implications for conservation in a declining peripheral population. Dissertation

Thesis

Full-text available

Dec 2012

Dawn Davis

Demography of Female Greater Prairie-Chickens in Unfragmented Grasslands in Kansas

Article

Full-text available

Jun 2011

Populations of Greater Prairie-Chickens (Tympanuchus cupido) have been declining because of loss and fragmentation of tallgrass prairie habitats, and management plans require contemporary demographic data. Our objectives were to determine whether maternal nutrition or predation were determinants of nesting success and female survival. We captured and radio-marked 43 females at four leks in natural, unfragmented prairie during a 4-year study. Reproductive potential was high because females laid large clutches (10.9 +/- 0.3 eggs, n = 24), renested following clutch loss (22.2%, n = 27 females), and had high egg viability (88.6 +/- 5.0% of eggs hatched; n = 7 nests), but reproductive traits were not correlated with female morphometrics (mass, or tarsus and keel lengths). Daily survival rate of nests was low (0.928, n = 34 nests) resulting in a predicted nest success rate of 7.4% for a 35-day exposure period. We used known fate models to estimate weekly survival from telemetry data for 40 females. Weekly survival was 0.970 and the extrapolated survival rate for the 6-month breeding season was 45.7%. Using time-sincemarking Cormack-Jolly-Seber models for live encounter data to control for transience, annual apparent survival was 0.277 +/- 0.081 SE for 55 marked females after initial capture, and 0.424 +/- 0.139 during subsequent intervals. Survival of females was 1.6 to 2.0 times higher during the nonbreeding season than the breeding season, presumably because females are susceptible to predation during incubation and broodrearing. Predation of nests and females may be the main demographic factors limiting population viability because predation, and not maternal nutrition, accounted for unexpectedly low nesting success and breeding season survival of Greater Prairie-Chickens in natural habitats. Future research should investigate rangeland practices that increase residual nesting cover or reduce predator impacts.

Population ecology of and the effects of hunting on ruffed grouse (Bonasa umbellus) in the southern and central Appalachians

Article

Full-text available

Demography, Reproductive Ecology, and Variation in Survival of Greater Sage-Grouse in Northeastern California

Article

Nov 2014
J WILDLIFE MANAGE

We examined demographic parameters and factors influencing nest survival of female greater sage-grouse (Centrocercus urophasianus) in northeastern California. Additionally, we used known-fate models in program MARK to examine bi-weekly survival rates of females over an 8-month period (Mar–Oct, 2007–2009). Nest survival rate, assuming a 38-day exposure period, was 41% and was positively associated with grass height ( = 0.03, SE = 0.02), but the 95% confidence interval overlapped 0 (95% CI = −0.007–0.767) and the effect of grass height on nest success was likely to be small. Grass height and visual obstruction was greater at nest sites than at random locations, suggesting females selected sites with structurally more closed habitat for nesting. Females that nested under vegetation other than sagebrush (Artemisia spp.) had increased nest survival probabilities, suggesting sage-grouse selection of nest sites is based on vegetation structure more than plant species. Sagebrush canopy cover was considerably lower in our study area (approx. 10% on random plots) compared with sagebrush cover described across the geographic range of sage-grouse (>15%) and sage-grouse use of non-sagebrush plants in our study suggests sagebrush nesting habitat is limited. The overall 8-month survival (breeding season through autumn migration) for female sage-grouse was 49% (SE = 0.06) with most deaths occurring in spring and autumn. Mortalities during spring coincided with nest initiation, incubation, and following hatch when successfully nesting females were tending to chicks. Mortalities in September coincided with dispersal and autumn migration. The survival estimate during the breeding season was greater among known failed nesters ( = 0.69) than females that nested successfully ( = 0.53), indicating female greater sage-grouse were exposed to greater mortality risk during incubation and brood-rearing periods. Greater mortality risk during the breeding season (i.e., nesting and brood-rearing) can have a major impact on greater sage-grouse demography. Conservation and management efforts should focus on enhancing female greater sage-grouse survival during the breeding and brood-rearing season. © 2014 The Wildlife Society.

EFFECTIVENESS OF THE SURROGATOR ® AT INCREASING NORTHERN BOBWHITE ABUNDANCE AND ENHANCING HUNTING

Article

Jacob Hagen

Ecology of greater sage-grouse in the Dakotas

Article

Jan 2009

Christopher C. Swanson

Fall survival of American woodcock in the Western Great Lakes Region

Article

Full-text available

Jul 2013
J WILDLIFE MANAGE

We estimated fall (10 Sep–8 Nov) survival rates, cause-specific mortality rates, and determined the magnitude and sources of mortality of 1,035 radio-marked American woodcock (Scolopax minor) in Michigan, Minnesota, and Wisconsin during 2001–2004. In all 3 states, we radio-marked woodcock on paired study areas; 1 of which was open to hunting and expected to receive moderate to high hunter use and the other of which was either closed to hunting (Michigan and Minnesota) or was relatively inaccessible to hunters (Wisconsin). We used Program MARK to estimate fall survival rates, to evaluate a set of candidate models to examine the effects of hunting and several covariates (sex, age, year, state) on survival, and to examine the relationship between survival rates and kill rates due to hunting. Hunting accounted for 70% of the 86 woodcock deaths in the hunted areas, followed by predation (20%) and various other sources of mortality (10%). Woodcock deaths that occurred in the non-hunted and lightly hunted areas (n = 50) were caused by predators (46%), hunting (32%), and various other sources (22%). Based on small-sample corrected Akaike's Information Criterion values, variation in fall survival of woodcock was best explained by treatment (i.e., hunted vs. non-hunted), year, and period (pre-hunting season intervals vs. hunting season intervals). The average fall survival estimate from our best model for woodcock in the non-hunted areas (0.893, 95% CI = 0.864–0.923) was greater than the average for the hunted areas (0.820, 95% CI = 0.786–0.854 [this estimate includes data from the lightly hunted area in Wisconsin]), and the average treatment effect (i.e., greater survival rates in non-hunted areas) was 0.074 (95% CI = 0.018–0.129). The kill rate due to hunting was 0.120 (95% CI = 0.090–0.151) when data were pooled among states and years. We detected a negative relationship between hunting kill rates and survival in our hunted areas, which suggests that hunting mortality was at least partially additive during fall. Our results illustrate the influence of hunting relative to other sources of mortality in Michigan, Minnesota, and Wisconsin, and indicate that managers may be able to influence fall survival rates by manipulating hunting regulations or access on public land. © 2013 The Wildlife Society.

Factors influencing the acquisition of rodent carrion by vertebrate scavengers and decomposers

Article

Full-text available

Mar 2004
CAN J ZOOL

Vertebrate scavengers and decomposers compete for animal carcasses in all temperate and tropical ecosystems. We examined the influence of carcass size, forest type, and air temperature on the fate of rodent carcasses at the Savannah River Site, South Carolina, USA. Three hundred rodent carcasses were placed at random locations in forested habitats and scavengers were identified using remote photography. Seventeen species of vertebrates removed 104 of 300 (35%) rodent carcasses over a year. Raccoons (Procyon lotor (Linnaeus, 1758)) and Virginia opossums (Didelphis virginiana Kerr, 1792) scavenged most frequently. For scavenged carcasses, the mean time to carcass removal was 2.58 days after placement. Carcass acquisition by scavengers and decomposers was influenced moderately by forest type and carcass size, although ambient air temperature considerably influenced the fate of carcasses. Vertebrates removed fewer carcasses as temperatures increased: only 28 of 144 (19%) carcasses were scavenged when temperatures exceeded 17°C. The temporal pattern of carcass removal by vertebrates, however, did not vary with temperature. Consistent rates of carcass removal by vertebrates across the year and increased activity by insects during warm weather led to elevated levels of decomposition during summer months. This study confirms the complexity and dynamic nature of competitive relationships among scavengers and decomposers.

Landscape distribution and ecology of Plio-Pleistocene avifaunal communities from Lowermost Bed II, Olduvai Gorge, Tanzania

Article

May 2014

Kari Prassack

Plio-Pleistocene avifaunal communities are used to reconstruct Lowermost Bed II landscapes at the early hominin site of Olduvai Gorge, Tanzania. These deposits are laterally extensive, have strong chronostratigraphic control, and were excavated using a landscape archaeological approach. Such factors allow for horizontal spatial-correlation of avian communities across the paleolandscape over a geologically short time frame (approximately 65,000 years). Lowermost Bed II avifaunal communities point to an extensive freshwater wetland system across the extent of paleo-Lake Olduvai's eastern margin.

Effects of wind energy development on survival of female greater prairie-chickens

Article

Full-text available

Apr 2014
J APPL ECOL

The potential effects of wind energy development on wildlife have received increased attention over the past decade. In Kansas, optimal sites for wind energy development often overlap with preferred habitats of greater prairie‐chickens T ympanuchus cupido . Our goal was to determine whether wind energy development affected survival of female prairie‐chickens in a grassland ecosystem, assessing one potential impact of wind on an upland gamebird of conservation concern. We focused primarily on the response of female prairie‐chickens to wind energy development because population dynamics of prairie‐chickens are primarily determined by female demography. We monitored prairie‐chickens at a wind facility in K ansas during a 2‐year pre‐construction (2007–2008) and a 3‐year post‐construction period (2009–2011). We used data from 220 radio‐marked females to calculate weekly survival and hazard rates. We used cause of death for 81 mortality events to test for changes in the proportion of mortalities attributed to mammalian predators, avian predators and collisions. We observed an unexpected increase in annual survival during the post‐construction period (0·57) compared with the pre‐construction period (0·32). Distance from home range centroid to the nearest wind turbine site had no effect on weekly survival of females. Collision mortality events were rare, and most were associated with fences or transmission lines and not turbine blades. Most female mortality was due to predation ( c . 90%). Differences in annual survival were driven by a higher risk of mortality during lekking activity in March and April during the pre‐construction period (weekly hazard rate = 0·050–0·062) compared with the post‐construction period (hazard rate = 0·012–0·021). We observed no change in the proportion of mortalities attributed to different causes between the two treatment periods. Synthesis and applications . Development of a wind energy facility had no negative effect on survival of female prairie‐chickens. The results of our field study indicate that greater prairie‐chickens are less sensitive to wind energy development than lesser prairie‐chickens T ympanuchus pallidicinctus and greater sage‐grouse C entrocercus urophasianus are to oil and gas development. We have strong evidence that survival increased after wind energy development, and hypothesize that energy development affected the local predator community, resulting in an indirect effect of decreased predation risk during the post‐construction period.

How Quickly are Road-killed Snakes Scavenged? Implications for Underestimates of Road Mortality

Article

Full-text available

Jun 2011

Annually, millions of snakes are killed on roads in the United States. Because of their potential abundance and ease of collection, many researchers have used road-killed snakes to examine community composition, movement patterns, and population dynamics. However, few previous studies have accounted for snake carcasses that are removed from roads by scavengers. Snake carcasses were placed at randomly selected locations along 2 km of road, one traversing maritime forest and the other surrounded by dune habitat. Carcasses in forested habitat were removed more often (100% vs 40%) and more quickly (8 hr vs 11 hr) than those placed in dune habitat. Half of the carcasses (50%) were removed within eight hours of placement and all carcasses were removed at night. Species and size of carcasses did not affect removal time. Removal time and scavenging intensity of snake carcasses most likely varies across regions and habitats. Furthermore, because scavenging appears to occur quickly and to such a significant extent, it may confound results of studies examining patterns of road-mortality. Thus, investigators that use data from road-killed snakes would benefit from a concurrent investigation of scavenging and application of appropriate correction factors to avoid underestimation of snake mortality.

Ruffed Grouse Survival and Population Structure in Western North Carolina

Article

Full-text available

Sound management of ruffed grouse ( Bonasa umbellus) populations requires an understanding of survival and cause-specific mortality; how - ever, these parameters have not been investigated at the southern extent of the species' range. Ruffed grouse were studied in the mountains of western North Carolina. Grouse (n = 276) were radiotagged and monitored >3 times/week. Mean annual survival was greater than reports from the northern core of the species' range. Seasonal survival was greatest in summer, followed by fall, winter, and spring. Of 155 mortalities, the greatest proportion was attrib- uted to mammalian, followed by avian, and unknown predation, hunter harvest, and other. Scavenging prior to transmitter recovery may have positively biased mammalian predation rates. Despite long hunting seasons that extended into winter, hunter harvest rates were among the lowest reported in the literature. Population densities, estimated annually in spring, were 5.9-11.4 grouse/100 ha and showed no association with hunter harvest. Survival rates showed an inverse relation with population density. Lower survival when population density was greatest may be related to habitat availability.

Wildlife crime scene investigation: Techniques, tools and technology

Article

Jan 2009

Wildlife crime, defined here as the illegal taking, disturbance, possession, trade or movement of animals and or their derivatives, is a growing international problem that threatens the survival of many species. In the investigation of such incidents the 'crime scene' may range from the carcass (or parts) of an animal to terrain that encompasses topography as varied as forest or desert and which may include diverse natural and man-made structures. Often, the location of the wildlife crime scene is isolated, with few facilities for proper investigation and collection of evidence. In poorer parts of the world and in countries experiencing social unrest, these features may present particular challenges. Wildlife crime scene work is such that equipment, investigative techniques and scientific technology all need to be appropriate to, and the best available in, the circumstances. Effective investigation under field conditions is likely to require a combination of portable and easy-to-use laboratory equipment coupled with modern methods of data collection and information transmission. An interdisciplinary approach is essential. Biologists/naturalists and those experienced in health studies, especially epidemiology, can often usefully complement the role of the police, enforcement officials and crime scene specialists.

Section 1: A Study of Factors Affecting Nesting Success and Mortality of Lesser Prairie-Chickens in Oklahoma

Article

Full-text available

Dec 2003

Project Objectives: The objectives of this study are to address potential causes of declines in the Lesser Prairie-Chicken (Tympanuchus pallidicinctus) through examination of habitat use, nesting success, and mortality rates via capture and radio-tracking of marked wild birds in western Oklahoma. Included is a comparison of these factors among dry-land cultivated, irrigated cultivated, native rangeland, introduced grass non-CRP pasture, native-mix CRP pasture, and Old World Bluestem CRP pasture, and across seasons for three years beginning July 2000.

Henslow's Sparrow Winter-Survival Estimates and Response to Prescribed Burning

Article

Full-text available

Sep 2009

Wintering Henslow's sparrow (Ammodramus henslowii) populations rely on lands managed with prescribed burning, but the effects of various burn regimes on their overwinter survival are unknown. We studied wintering Henslow's sparrows in coastal pine savannas at the Mississippi Sandhill Crane National Wildlife Refuge, Jackson County, Mississippi, USA, during January and February 2001 and 2002. We used the known-fate modeling procedure in program MARK to evaluate the effects of burn age (1 or 2 growing seasons elapsed), burn season (growing, dormant), and calendar year on the survival rates of 83 radiomarked Henslow's sparrows. We found strong evidence that Henslow's sparrow survival rates differed by burn age (with higher survival in recently burned sites) and by year (with lower survival rates in 2001 likely because of drought conditions). We found some evidence that survival rates also differed by burn season (with higher survival in growing-season sites), although the effects of burn season were only apparent in recently burned sites. Avian predation was the suspected major cause of mortality (causing 6 of 14 deaths) with 1 confirmed loggerhead shrike (Lanius ludovicianus) depredation. Our results indicated that recently burned savannas provide high-quality wintering habitats and suggested that managers can improve conditions for wintering Henslow's sparrows by burning a large percentage of savannas each year.

Effects of feeders on dispersion and mortality of bobwhites

Article

Jan 2004

We assessed supplemental feeding in a crossover design to determine its value in managing the dispersion and mortality of northern bobwhites (Colinus virginianus) in Roberts County, Texas Panhandle, during October–March 2000–2001, 2001–2002, and 2002–2003. Nontarget species made up 98% of feeder visits (n=152 visits in 480 hours of surveillance). The average home range (ha) on the fed site was 34% of that on the control site (95% CL=21–48%) in 2001–2002 and 63% (39–103%) in 2002–2003, suggesting that feeders localized coveys. Fall-spring survival estimates were 0.57 (0.40–0.73) on the fed site versus 0.72 (0.53–0.91) on the control site in 2001–2002; estimates were 0.24 (0.16–0.33) on the fed site versus 0.28 (0.22–0.34) on the control site in 2002–2003, indicating null effects of feeding on fall-spring survival. Apparent vulnerability of bobwhites to loss sources (avian or mammalian predators, other losses) was not affected by feeding. Based on our results, managers who wish to localize coveys could accomplish that objective using feeders; otherwise, food supplementation was a neutral management practice.

Ruffed Grouse Population Ecology in the Appalachian Region

Article

Full-text available

Dec 2010
WILDLIFE MONOGR

The Appalachian Cooperative Grouse Research Project (ACGRP) was a multistate cooperative effort initiated in 1996 to investigate the apparent decline of ruffed grouse ( Bonasa umbellus ) and improve management throughout the central and southern Appalachian region (i.e., parts of Ohio, Pennsylvania, Rhode Island, Kentucky, West Virginia, Virginia, and North Carolina, USA). Researchers have offered several hypotheses to explain the low abundance of ruffed grouse in the region, including low availability of early‐successional forests due to changes in land use, additive harvest mortality, low productivity and recruitment, and nutritional stress. As part of the ACGRP, we investigated ruffed grouse population ecology. Our objectives were to estimate reproductive rates, estimate survival and cause‐specific mortality rates, examine if ruffed grouse harvest in the Appalachian region is compensatory, and estimate ruffed grouse finite population growth. We trapped >3,000 ruffed grouse in autumn (Sep‐Nov) and spring (Feb‐Mar) from 1996 to September 2002 on 12 study areas. We determined the age and gender of each bird and fitted them with necklace‐style radiotransmitters and released them at the trap site. We tracked ruffed grouse ≥2 times per week using handheld radiotelemetry equipment and gathered data on reproduction, recruitment, survival, and mortality. Ruffed grouse population dynamics in the Appalachian region differed from the central portion of the species' range (i.e., northern United States and Canada). Ruffed grouse in the Appalachian region had lower productivity and recruitment, but higher survival than reported for populations in the Great Lakes region and southern Canada. Population dynamics differed between oak ( Quercus spp.)–hickory ( Carya spp.) and mixed‐mesophytic forest associations within the southern and central Appalachian region. Productivity and recruitment were lower in oak‐hickory forests, but adult survival was higher than in mixed‐mesophytic forests. Furthermore, ruffed grouse productivity and recruitment were more strongly related to hard mast (i.e., acorn) production in oak‐hickory forests than in mixed‐mesophytic forests. The leading cause of ruffed grouse mortality was avian predation (44% of known mortalities). Harvest mortality accounted for 12% of all known mortalities and appeared to be compensatory. Population models indicated ruffed grouse populations in the Appalachian region are declining (%LD = 0.78–0.95), but differences in model estimates highlighted the need for improved understanding of annual productivity and recruitment. We posit ruffed grouse in the Appalachian region exhibit a clinal population structure characterized by changes in life‐history strategies. Changes in life history strategies are in response to gradual changes in forest structure, quality of food resources, snowfall and accumulation patterns, and predator communities. Management efforts should focus on creating a mosaic of forest stand ages across the landscape to intersperse habitat resources including nesting and brood cover, adult escape cover, roosting sites, and, most importantly, food resources. Land managers can intersperse habitat resources through a combination of clearcutting, shelterwood harvests, group selection, and timber stand improvement (including various thinnings and prescribed fire). Managers should maintain current ruffed grouse harvest rates while providing high quality hunting opportunities. We define high quality hunting as low hunting pressure, low vehicle traffic, and high flush rates. Managers can provide high quality hunting opportunities through use of road closures in conjunction with habitat management. RESUMEN El proyecto de investigación cooperativo del grouse superado de apalache (ACGRP) era un esfuerzo cooperativo del multi‐estado iniciado en 1996 para investigar la declinación evidente del grouse superado ( Bonasa umbellus ) y para mejorar el manejo a través de la región apalache central y meridional (es decir, partes de Ohio, de Pennsylvania, de Rhode Island, de Kentucky, de Virginia Occidental, de Virginia, y de Tennessee, en los E.E.U.U.). Como parte de la ACGRP, investigamos la ecología superada de la población del grouse superado. Nuestros objetivos eran: estimar las tarifas reproductivas, estimar la supervivencia y las tarifas causar‐específicas de la mortalidad, examinar si la cosecha del grouse superado en la región apalache es compensatoria, y estimar el crecimiento finito superado de la población del grouse superado. Varias hipótesis se han ofrecido para explicar la abundancia baja del grouse superado en la región, incluyendo la disponibilidad baja de los bosques jóvenes debido a los cambios en utilización del suelo, mortalidad aditiva de la cosecha, bajo productividad y reclutamiento, y tensión alimenticia. Atrapamos grouse superado >3,000 en el otoño (septiembre a noviembre) y en la primavera (febrero a marzo) a partir de 1996 al septiembre de 2002 en 12 áreas del estudio. Determinamos la edad y el sexo de cada pájaro y los cupimos con los radio‐transmisores del estilo collar y los lanzamos en el sitio de la trampa. Seguimos el grouse superado ≥2 veces por semana usando equipo de la telemetría de radio de la estilo de mano y recopilamos datos sobre la reproducción, el reclutamiento, la supervivencia, y la mortalidad. La dinámica de población del grouse superado en la región apalache diferenció de la porción central alcance de la del especie (es decir, el norte de los Estados Unidos y Canadá). El grouse superado en la región apalache tenía una productividad y un reclutamiento más bajo, pero supervivencia más alta que divulgada para las poblaciones en la región de los Great Lakes y el Canada meridional. La dinámica de población diferenció entre bosques del roble ( Quercus ), el nuez dura ( Carya ) y bosques del estilo mesophytic mezclado dentro de la región apalache meridional y central. La productividad y el reclutamiento eran más bajos en bosques del roble yel nuez dura, pero la supervivencia del adulto era más alta que en bosques mesophytic mezclados. Además, la productividad y reclutamiento del grouse superado fueron relacionados más fuertemente a la producción dura del mástil (es decir, bellota) en bosques del roble y nuez dura que en bosques mesophytic mezclado. La causa principal de la mortalidad del grouse superado era la depredación aviar (el 44% de mortalidades sabidas). La mortalidad de la cosecha explicó el 12% de todas las mortalidades sabidas y aparecía ser compensatoria. Los modelos de población indican que las poblaciones del grouse superado en la región apalache están declinando (Λ = 0.78–0.95), pero las diferencias en las estimaciones modelo indican la necesidad de la comprensión mejorada de la productividad y del reclutamiento anuales. Postulamos que el grouse superado en la region apalache muestra una estructura de la población clinal con los cambios en estrategias de la vida‐historia en respuesta a cambios graduales en la calidad de los recursos del alimento, las nevadas y los patrones de la acumulación, y las comunidades despredadoras. Los esfuerzos del manejo deben centrarse en crear un mosaico de las edades del soporte de bosque a través del paisaje para entremezclar recursos del habitat incluyendo la cubierta para nidos y la cría de jovenes, la cubierta del escape del adulto, sitios para perchas, y más importante recursos del alimento. Interspersion de los recursos del habitat se puede lograr con una combinación de cortes selectivos, de los cortes del claro, del fuego prescrito, y de crear boquetes de diámetro bajo del pabellón matando a árboles individuales. El manejo de la cosecha se debe diseñar para mantener tarifas actuales de la cosecha mientras que proporciona oportunidades de la caza de la alta calidad. Definimos la caza de la alta calidad como la presión baja de la caza, el tráfico bajo del vehículo, y tarifas rasantes del colmo. El manejo de la caza de la alta calidad puede ser lograda con el uso de los encierros del camino conjuntamente con el manejo del habitat. Écologie de Population de Grouse de Ruffed dans la Région Appalachienne RÉSUMÉ Le projetde recherche coopératif appalachien (ACGRP) était un effort coopératif de multi‐état lancé en 1996 pour étudier le déclin apparent de ruffed la grouse ( Bonasa umbellus ) et améliorent la gestion dans toute la région appalachienne centrale et méridionale (c.‐à‐d., régions de l'Ohio, de la Pennsylvanie, de Île de Rhode, du Kentucky, de la Virginie Occidentale, de la Virginie, et du Tennessee, Etats‐Unis). En tant qu'élément de l'ACGRP, nous avons étudié ruffed l'écologie de population de grouse. Nos objectifs étaient: estimer les taux reproducteurs, estimer la survie et les taux causer‐spécifiques de mortalité, les examiner si ruffed la grouse que la moisson dans la région appalachienne est compensatoire, et l'évaluation ruffed la croissance finie de population de grouse. Plusieurs hypothèses ont été offertes pour expliquer la basse abondance de ruffed la grouse dans la région, y compris la basse disponibilité des forêts d'early‐successional dues aux changements de l'utilisation de la terre, la mortalité additive de moisson, la productivité et le recrutement faible, et l'effort alimentaire. Nous avons emprisonné >3,000 ruffed la grouse en automne (Septembre.–Nov.) et ressort (Fév.–Mars.) de 1996 au Septembre 2002 sur 12 secteurs d'étude. Nous avons déterminé l'âge et le sexe de chaque oiseau et les avons équipés des émetteurs par radio de collier‐modèle et les avons libérés à l'emplacement de piège. Nous avons dépisté ruffed des temps de la grouse ≥2 par semaine à l'aide de l'équipement tenu dans la main de radiotélémétrie et avons recueilli des données sur la reproduction, le recrutement, la survie, et la mortalité. La dynamique de population de grouse de Ruffed dans la région appalachienne a différé de la partie centrale de la gamme des espèces (c.‐à‐d., les Etats‐Unis et le Canada nordiques). La grouse de Ruffed dans la région appalachienne a eu une productivité et un recrutement plus faible, mais une survie plus élevée que rapportée aux populations la région de Great Lakes et au Canada méridional. La dynamique de population a différé entre le chêne ( quercus )–hickory ( Carya ) et associations mélangées‐mesophytic de forêt dans la région appalachienne méridionale et centrale. La productivité et le recrutement étaient inférieurs dans des forêts de chêne‐hickory, mais la survie d'adulte était plus haute que dans les forêts mélangées‐mesophytic. En outre, ruffed la productivité de grouse et le recrutement plus fortement ont été lies à la production dure de mat (c.‐à‐d., gland) dans des forêts de chêne‐hickory que dans les forêts mélangées‐mesophytic. La principale cause de ruffed la grouse que la mortalité é tait la prédation aviaire (44% de mortalités connues). La mortalité de moisson a expliqué 12% de toutes les mortalités connues et a semblé ê tre compensatoire. La population que les modèles indiquent ruffed la grouse les populations dans la région appalachienne refusent (Λ = 0.78–0.95), mais les differences dans les évaluations modèles indiquent le besoin d'arrangement amélioré de la productivité et du recrutement annuels. Nous posons en principe ruffed la grouse dans l'objet exposé appalachien de région une structure de population de clinal avec des changements des stratégies de vie‐histoire en réponse aux changements progressifs de la qualité des ressources de nourriture, des chutes de neige et des modèles d'accumulation, et des communautés prédatrices. Les efforts de gestion devraient se concentrer sur créer une mosaïque des âges de peuplement de forêt à travers le paysage pour entremêler des ressources d'habitat comprenant la couverture d'emboîtement et de couvée, la couverture d'évasion d'adulte, les emplacements roosting, et d'une manière plus importante les ressources de nourriture. Interspersion des ressources d'habitat peut être accompli par une combinaison des coupes sélectives, des coupes d'espace libre, du feu prescrit, et de créer des lacunes de faible diamètre de verrière en tuant différents arbres. La gestion de moisson devrait être conçue pour maintenir des taux courants de moisson tout en fournissant des occasions de chasse de qualité. Nous définissons la chasse de qualité en tant que la basse pression de chasse, le bas trafic de véhicule, et taux affleurants de haute. La gestion de chasse à qualité peut être accomplie par l'utilisation des fermetures de route en même temps que la gestion d'habitat.

Survival of a polymorphic species in seasonally snow‐covered forests

Article

Nov 2023

Color polymorphism is an adaptive strategy in which a species exhibits multiple color phenotypes in a population. Often, phenotypes are variably suited to different environmental conditions which may buffer the population against variable conditions. Modern climate change is creating novel selective pressures for many species, especially in winter habitats. Few studies have quantified the benefits of polymorphism for allowing species to cope with climate‐induced environmental change, particularly for species with more cryptic differences between morphs. We investigated how color polymorphism mediates selective pressures in ruffed grouse Bonasa umbellus , a winter‐adapted bird species of North American forests. Ruffed grouse display phenotypic variation in plumage color, ranging from red to gray. Over five winters (2015–2022), we monitored weather conditions, habitat use, and weekly survival for 94 grouse to test whether individuals had lower survival when phenotypically mismatched with snow cover (e.g. a gray bird on a snowless landscape or a red bird in snow). Grouse phenotypically mismatched with snow cover had lower survival, but only when winter survival rates were lowest. During winters of lower overall survival, red grouse exhibited higher survival during snow‐free periods, whereas gray grouse had higher survival when snow was present. We also found that open habitat negatively impacted survival, regardless of color. While the effect of phenotypic mismatch was variable among years, it was a stronger predictor of survival than land cover, suggesting that snow is an important habitat feature mediating overwinter survival. Our work offers an advancement in understanding how environmental variability affects geographic variation in and maintenance of multiple color phenotypes in seasonally‐snow covered environments. Our finding that interactions between color morph and snow cover are important for conferring winter survival provides further evidence that color polymorphism may serve as a buffer against rapidly changing conditions and a pathway for persistence of polymorphic species. Keywords: Bonasa umbellus , color polymorphism, phenotypic mismatch, ruffed grouse, winter ecology, Wisconsin

Feeds of animal origin in rabbit nutrition – a review

Article

Full-text available

Sep 2022
ANN ANIM SCI

Rabbits are classified as obligate herbivores. However, under natural conditions, some members of the family Leporidae incorporate animal products into their diets. Therefore, it seems biologically justified to supplement the diets of farmed rabbits with feeds of animal origin as sources of protein, fat and minerals. The aim of this review was to describe, from a historical perspective, the use of various feeds of animal origin in rabbit nutrition. The applicability of by-products from mammal, poultry, fish and invertebrate processing for rabbit feeding was evaluated, including the future prospects for their use. A review of the available literature revealed that various animal-based feeds can be valuable protein sources in rabbit diets, but their inclusion levels should not exceed 5-10%. Studies investigating their efficacy have been conducted since the 1970s. In some regions of the world, the use of animal-derived protein in livestock feeds was prohibited due to the risk of spreading bovine spongiform encephalopathy (BSE). However, the interest in animal by-products as protein sources in livestock diets is likely to increase since the above ban has been lifted.

Increased abundance of a common scavenger affects allocation of carrion but not efficiency of carcass removal in the Fukushima Exclusion Zone

Article

Full-text available

May 2022

The 2011 nuclear accident in Fukushima, Japan caused the evacuation of > 100,000 people and prompted studies on environmental impacts of radiological contamination. However, few researchers have explored how the human evacuation has affected ecosystem processes. Despite contamination, one common scavenger (wild boar, Sus scrofa) is 2–3× more abundant inside the Fukushima Exclusion Zone (FEZ). Shifts in abundance of some scavenger species can have cascading effects on ecosystems, so our objective was to investigate impacts of the evacuation and the resulting increase in wild boar on vertebrate scavenger communities. We deployed cameras at 300 carcasses in the FEZ and a nearby inhabited area, and quantified carcass fate, scavenger species, and detection/persistence times. We also tested effects of carcass size and habitat on scavenger community composition and efficiency by balancing trials across two carcass sizes and habitats in each zone. Overall scavenger richness and carcass removal rates (73%) were similar in the FEZ and inhabited area, but species-specific carcass removal rates and occurrence differed between zones. Wild boar removed substantially more carcasses inside the FEZ, with implications for nutrient and contaminant distribution. Our results suggest carcass size affects scavenging dynamics more than human activity or habitat, and abundance changes of common scavengers can influence carrion resource allocation.

Hunting and environmental influences on survival of male wild turkeys in Virginia and West Virginia

Article

May 2022

Knowledge of the effects of hunting and environmental influences on survival of eastern wild turkeys (Meleagris gallopavo silvestris) is critical to managers setting fall and spring hunting seasons. Research has shown improper season frameworks can result in unsustainably high harvest rates of adult males, affect male age structure, and result in lower hunter satisfaction. Our objectives were to estimate survival rates of males, identify causes of mortality, and relate hunting and environmental influences to male turkey survival. We captured and radio‐tagged male wild turkeys in Virginia (n = 204) and West Virginia (n = 197), USA, during 2004–2007. We used staggered entry Kaplan‐Meier models to estimate survival and Cox Proportional Hazards Models to estimate effects of predictor variables on survival. Survival was estimated for 3 distinct periods of interest: annual, fall hunting (October–January), and spring hunting (April–May). The leading causes of mortalities (209 turkeys) were legal spring harvest (42%), predation (25%), and poaching (17%). Only 8 turkeys (4%) were taken during fall hunting seasons. Confidence intervals for annual survival of 2 year‐old and 3+ year‐old turkeys overlapped; therefore, we combined adult ages into a single category (2+). Adult (2+) annual survival was 0.63 (95% CI = 0.58–0.69) and the harvest rate was 25% (95% CI = 20–29%) for the combined states. Annual survival rates for adults (2+) were greater than in most other published studies, whereas adult (2+) spring harvest rates were lower. For juvenile males, annual survival was 0.74 (95% CI = 0.68–0.79) and spring harvest rate was 7% (95% CI = 3–11%). High juvenile and adult (2+) survival may have been related to low harvest rates. Adult turkeys (2+) had 46% greater risk of dying than one‐year‐old birds and were 3.7 times more likely to be harvested than juveniles. Age, a relative phenology index (RPI; spring green‐up), and white oak (Quercus alba) acorn production were included in the top models for annual survival, spring season survival, and spring harvest risk. Increasing RPI (more foliage) decreased mortality risk and greater white oak (Quercus alba) acorn abundance increased mortality risk. Across 4 regions in the 2 states, fall survival was high (0.90, 95% CI = 0.87–0.93). The impact of fall hunting on males in Virginia was low (5% harvest rate, 95% CI = 0–9%). Overall, spring harvest had the greatest effect on male survival, although those effects were moderated by the previous fall white oak crop and the onset of green‐up in the spring. Knowledge of the effects of hunting and environmental influences on survival of eastern wild turkeys (Meleagris gallopavo silvestris) is critical to managers setting fall and spring hunting seasons. Improper season frameworks can result in unsustainably high harvest rates of adult males, affect male age structure, and result in lower hunter satisfaction. Our objectives were to estimate survival rates of males, identify causes of mortality, and relate hunting and environmental influences to male turkey survival. Over 3 years (2004‐2007), we captured and radio‐tagged male wild turkeys in Virginia (n = 204) and West Virginia (n = 197), USA. Adult birds (2+) had 46% greater risk of dying than 1‐year‐old birds and were 3.7 times more likely to be harvested than juveniles. The impact of fall hunting on male turkey annual survival in Virginia was low.

Survival and harvest of ruffed grouse in central Maine, USA

Article

Aug 2017

Understanding population dynamics is central to population management, particularly for game species that experience human harvest and non‐harvest mortality. Ruffed grouse (Bonasa umbellus) are a widely distributed and common game species in North America that have experienced population declines along their southern range margins, including portions of New England, primarily in response to forest succession and habitat loss. In the state of Maine, ruffed grouse are generally considered abundant, but there is a lack of state‐specific knowledge of ruffed grouse survival and harvest rates to inform harvest management. We estimated seasonal and annual survival rates, harvest rates, and documented cause‐specific mortality of 248 radio‐marked ruffed grouse at 2 study areas in central Maine from 2014 to 2016. We used Program MARK to evaluate sources of spatial, temporal, and individual variation that may affect ruffed grouse survival and harvest. Survival was lowest during October and during winter, and adult ruffed grouse had a higher survival probability than juveniles throughout the year with mean annual survival probabilities of 0.28 ± 0.01 (SE) and 0.13 ± 0.003, respectively. Harvest rates were greater in a state‐owned Wildlife Management Area and were lower within commercially managed private forest that was open to public hunting. Harvest results suggest harvest (H) was greatest at the beginning of the hunting season (Oct; Frye Mountain HOct = 0.14 ± 0.02; Stud Mill HOct = 0.07 ± 0.02), and was lower later in the season (Nov and Dec; Frye Mountain HNov‐Dec = 0.07 ± 0.02; Stud Mill HNov‐Dec = 0.03 ± 0.01). Pooled across all years and study areas, the ruffed grouse harvest rate was 0.16 (95% CI = 0.14–0.18). Our results are comparable to other range‐wide studies and suggest that current hunting regulations for ruffed grouse in Maine are consistent with sustainable population management. © 2018 The Wildlife Society.

Testing Different Search Methods for Recovering Scattered and Scavenged Remains

Article

Dec 2008

Vertebrate scavengers are primary mechanisms for scatter and disarticulation of human remains in rural habitats. Because recovery of the body can be hampered by the degree of scatter due to scavengers, the methods used to search for body parts will influence how much is found and the length of time taken to recover the body. We compared the frequency of scavenging by vertebrates in two different habitats, a deciduous forest and a tall grass meadow, and measured the time taken to search for scattered remains within a designated search area using four methods. Freshly killed 23 kg pigs were placed in either a forest or tall grass meadow habitat, and scavenging by vertebrates was observed over a 5–6 day period. Subsequently, the link, line, zone, and spiral methods were used to search for remains within a 21 m2 search area. Three of 5 pigs in the forest and 4 of 5 pigs in the meadow habitat were scavenged by a variety of vertebrates. Mean time to search the designated area around each pig differed between the forest and the meadow, but not by search method. Mobility within each habitat likely explains the difference in search times, and also accounts for some of the variability between search methods.

Implications of Woodrats and Other Scavengers for Avian Telemetry Studies

Article

Dec 2010
J WILDLIFE MANAGE

During 2 years of radiotelemetry research on chukars (Alectoris chukar) in western Utah, USA, we found 28% of retrieved radios (n = 78) in rubbish nests of woodrats (Neotoma spp.). Such movement and disturbance of carcasses and radios by woodrats and other species has implications for radiotelemetry studies. We evaluated spatio-temporal movement of 51 radiocollars attached to chukar carcasses in western Utah. Most (80%) carcasses were scavenged within one week and by the end of 3 weeks 25 (50%) had been retrieved from woodrat middens. Scavenging activity can both obscure important clues needed to identify causes of mortality and bias telemetry studies by delaying onset of mortality signals.

Winter Survival Rates of American Woodcock in South Central Louisiana

Article

Full-text available

Oct 2000
J WILDLIFE MANAGE

Richard Mears Pace

Declines in abundance of American woodcock (Scolopax minor; hereafter woodcock) have led to more restrictive hunting regulations imposed by the U.S. Fish and Wildlife Service, although there is little evidence to suggest that declines were related to hunting. To estimate winter survival and document hunting mortality rates, I radiotagged 160 female woodcock on a public hunting area in south central Louisiana. Woodcock were captured in fields at night from late November through December during 1994-96 and monitored at least daily. At least 37 woodcock died, primarily from avian predators. Day of capture and condition at date of capture were not predictive of survival. Survival rates were similar across ages and years except for lower survival of juvenile birds during 1993-94. The overall survival rate for the period 1 December to 15 February (77 days) was 72 ± 5%, which was the same or higher than reported elsewhere in winter. Hunting mortality varied from 1.6 to 12.2%, which seemed relatively low given the ample public hunting opportunity and a high winter-long fidelity to the study area.

Why are lead-poisoned waterfowl rarely seen?: the disappearance of waterfowl carcasses in the Camargue, France

Article

Jan 1991

Deborah Pain

With a high carcass density (50 birds in 7.8 ha) scavenging rates were very rapid. Carcasses in exposed positions on land persisted for on average 1.5 days, those concealed by vegetation for 3.3 days and those exposed on water for 7.6 days. These differences are probably related to the identity and abundance of predators and scavengers and their foraging routes. High lead poisoning waterfowl mortality thus may occur unnoticed by hunters. -from Author

Predation and Hunting Mortality of Ruffed Grouse in Central Wisconsin

Article

Jul 1991

We monitored 381 radio-marked ruffed grouse (Bonasa umbellus) on public and private wood-lands in central Wisconsin during 1982-88 to determine seasonal mortality rates due to predation and hunting. A total of 222 known mortalities were recorded: 159 from predation and 63 from hunting. Adult survival rates gradually decreased from 0.85 in summer to 0.57 in winter, then increased in spring to 0.73. Juvenile survival was also highest in summer (0.61), but remained relatively low through all seasons. Hunting mortality rates on public hunting areas were significantly (P < 0.005) higher than on private lands for both adults (0.73 vs. 0.13) and juveniles (0.56 vs. 0.09). In contrast, mortality (viz., predation) was similar during the nonhunting season on public and private lands for both adults (0.44 vs. 0.44) and juveniles (0.80 vs. 0.77, respectively), suggesting that hunting mortality was at least partially, if not completely, additive to natural mortality. Immigration from private lands sustained grouse numbers on public lands because overall population densities gradually increased from 5.8 to 7.8 drumming males per 100 ha during the 6-year study. We conclude that ruffed grouse numbers will be substantially reduced in areas with high hunting mortality and reduced immigration due to fragmented habitat.

Migration by Radio-Tagged Pacific Golden-Plovers from Hawaii to Alaska, and Their Subsequent Survival

Article

Jul 1997

Use of salmonid carcasses by vertebrate scavengers

Article

Jan 1995
J ZOOL

R. Hewson

The use of salmon Salmo salar carrion by otters Lutra lutra and other scavengers along the River Dee in north-east Scotland was studied by radio-tagging and individual marking of fish carcasses. More carcasses were available on the Dee than on tributary streams used for spawning, indicating that salmon returned to the river after spawning and died there. The amount of salmon carrion available to terrestrial and avian scavengers along the Dee varied from 6.7 kg. km-1 on an upstream study area to 36 kg. km-1 downstream. Fish carcasses in the Dee were moved by spates up to 20 km but in streams used for spawning less than 1 km. Of 86 carcasses examined in 1990/91, 64 were available to terrestrial and avian scavengers on the bank or awash and of these 45 had been fed upon by otters and 16 by birds. In 1991/92, 23 of 30 carcasses were available to terrestrial and avian scavengers. All had been fed upon, 19 by otters, four by birds. Other carcasses, in shallow water, were not available to terrestrial and avian scavengers. Subsequent scavenging was mainly by otters and continued for up to three weeks after the carcasses were found. Heron Ardea cinerea, great black-backed gull Larus marinus and crow Corvus corone also scavenged salmon carcasses along the Dee. Great black-backed gulls were the most frequent scavengers, but heron (dominant to black-backed gull) was a major scavenger in 1990/91. Crows, subordinate to other scavengers, waited, often in pairs, upon dominant scavengers. There were more scavenging birds downstream and numbers did not change between years. Of 20 salmon carcasses placed in spawning areas eight were probably, two possibly, removed by otters. Otters continued to scavenge carcasses for up to a month. Scavenging by foxes Vulpes vulpes and birds followed the removal of fish carcasses from the water by otters. Radio transmitters were removed by otters and left lying alongside carcasses.

Null Hypothesis Testing: Problems, Prevalence, and an Alternative

Article

Oct 2000

This paper presents a review and critique of statistical null hypothesis testing in ecological studies in general, and wildlife studies in particular, and describes an alternative. Our review of Ecology and the journal of Wildlife Management found the use of null hypothesis testing to be pervasive. The estimated number of P-values appearing within articles of Ecology exceeded 8,000 in 1991 and has exceeded 3,000 in each year since 1984, whereas the estimated number of P-values in the Journal of Wildlife Management exceeded 8,000 in 1997 and has exceeded 3,000 in each year since 1991. We estimated that 47% (SE = 3.9%) of the P-values in the Journal of Wildlife;fe Management lacked estimates of means or effect sizes or even the sign of the difference in means or other parameters. We find that null hypothesis testing is uninformative when no estimates of means or effect size and their precision are given. Contrary to common dogma, tests of statistical null hypotheses have relatively little utility in science and are not a fundamental aspect of the scientific method. We recommend their use be reduced in favor of more informative approaches. Towards this objective, we describe a relatively new paradigm of data analysis based on Kullback-Leibler information. This paradigm is an extension of likelihood theory and, when used correctly, avoids many of the fundamental limitations and common misuses of null hypothesis testing. Information-theoretic methods focus on providing a strength of evidence for an a priori set of alternative hypotheses, rather than a statistical test of a null hypothesis. This paradigm allows the following types of evidence for the alternative hypotheses: the rank of each hypothesis, expressed as a model; an estimate of the formal likelihood of each model, given the data; a measure of precision that incorporates model selection uncertainty; and simple methods to allow the use of the set of alternative models in making formal inference. We provide an example of the information-theoretic approach using data on the effect of lead on survival in spectacled elder ducks (Somateria fischeri). Regardless of the analysis paradigm used, we strongly recommend inferences based on a priori considerations be clearly separated from those resulting from some form of data dredging.