bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal change in the morphometry–body mass relationship of polar bears
Authors: Thiemann Gregory W. , Lunn Nicholas J. , Richardson Evan S. , Andriashek Dennis S. 
Published: May 2011

AbstractAccurate information on animal body mass is often an essential component of wildlife research and management. However, for many large‐bodied species, obtaining direct scale weights from individuals may be difficult. In these cases, morphometric equations (e.g., based on girth or length) may provide accurate and precise estimates of body mass. We developed predictive equations to estimate the body mass of free‐ranging polar bears (Ursus maritimus) in western Hudson Bay, Canada. Using multiple linear and non‐linear regression, we identified a strong relationship between polar bear body weight and linear measures of straight line length and axillary girth. The mass–morphometry relationship appeared to change over time and we developed separate equations for polar bears measured during 2 time periods, 1980–1996 and 2007–2009. Non‐linear models were more accurate and provided body mass estimates within 5.8% (R2 = 0.98) and 6.1% (R2 = 0.98) of scale weight in the earlier and later time periods, respectively. Earlier equations developed for polar bears in this subpopulation performed poorly when applied to recently sampled individuals. In contrast, some contemporary equations from other regions performed reasonably well, suggesting that temporal changes within a subpopulation may be more pronounced than regional differences and can render earlier predictive equations obsolete. Our results have important implications for current and future studies of polar bear body condition and the effects of ongoing climate warming. © 2011 The Wildlife Society.
Estimating occupancy to monitor northern goshawk in the central Rocky Mountains
Authors: Beck Jeffrey L. , Skorkowsky Robert C. , Hayward Gregory D. 
Published: May 2011

AbstractDesigning monitoring programs to evaluate trends in low‐density wildlife species at regional scales is challenging given difficulties detecting uncommon organisms distributed in potential habitats over large spatial extents. The northern goshawk (Accipiter gentilis) has been petitioned for listing under the Endangered Species Act and the review of the petition indicated a need for information on population trend. To evaluate trends in goshawk populations, the U.S. Forest Service developed the Northern Goshawk Bioregional Monitoring Design to estimate goshawk occupancy over broad spatial extents. We adapted and implemented this design to approximately 30,600 km2 of 88,128 km2 of National Forest System lands in the Forest Service Rocky Mountain Region, including portions of Colorado, Wyoming, and South Dakota. We developed a stratified random design to monitor goshawk occupancy in sampling units, defined by primary and secondary habitat quality as well as accessibility. To define habitat quality, we examined a time series for 58 previously located nesting territories. Using logistic regression, we found that the dominant conifer species and status of aspen in postfledging zones best characterized high‐quality goshawk nesting habitat. We applied model results to stratify 4,445 sampling units based on habitat quality and further stratified sampling units based on accessibility into easy and difficult access categories. We conducted field sampling during the goshawk breeding season in the summer of 2006 to estimate detection probabilities and occupancy rates. Within our sampling frame, we sampled 51 sampling units and estimated goshawk occupancy of 0.329 (95% CI: 0.213–0.445). Occupancy within primary strata (high quality) sampling units was 0.811 (SE = 0.113), whereas occupancy in secondary strata (lower quality) sampling units was 0.124 (SE = 0.067). Future implementation of this monitoring program can achieve 0.8 power to detect 30–40% declines in with 140 sampling units. Our implementation of a stratified sampling design to monitor occupancy of goshawks at a region‐wide scale reduced the number of sampling units in each administrative unit and focused our efforts on those areas most likely to have goshawks. © 2011 The Wildlife Society.
Effects of supplemental feeding and density of white‐tailed deer on rodents
Authors: Moseley William A. , Cooper Susan M. , Hewitt David G. , Fulbright Timothy E. , Deyoung Charles A. 
Published: May 2011

AbstractSpatial distribution, population density, and reproductive success of many wildlife species may be altered by changes in vegetation composition, habitat structure, and availability of food. Altered distributions of key herbivores such as white‐tailed deer (Odocoileus virginianus) may impact all of these factors. Our objective was to determine the direct and indirect effects of supplemental feeding of deer on rodent populations in south Texas. We modeled effects of supplemental feeding and habitat change due to deer browsing through surveys of rodents. Rodents have a short generation time and populations respond quickly to change, so they are a suitable indicator of changes in habitat structure brought about by deer browsing pressure. We sampled rodent populations near to and far from deer feeders within twelve 81‐ha enclosures containing three different densities of deer with and without supplemental feed. The three deer densities were low (8.1 ha/deer), medium (3.2 ha/deer), and high (2 ha/deer). We conducted rodent trapping during March and April of 2007 and 2008. Abundance of rodents was much higher (P < 0.001) in 2008 than in the previous year due to an increase in rainfall. However, we found little effect of deer density, supplemental feeding of deer, or distance from deer feeders on rodent populations. Thus we conclude that supplemental feeding of deer and deer density had little influence on rodent communities in this environment. Rodent species native to semi‐arid environments are probably adapted to large changes in vegetative productivity brought about by the highly variable annual rainfall patterns, therefore they can adapt to the less abrupt habitat changes resulting from changing densities of deer. Conservation concerns that providing supplemental feed to deer in semi‐arid rangeland will disrupt the ecology of the land through changes in rodent populations were not supported. © 2011 The Wildlife Society.
Efficiency of time‐lapse intervals and simple baits for camera surveys of wild pigs
Authors: Williams Brian L. , Holtfreter Robert W. , Ditchkoff Stephen S. , Grand James B. 
Published: May 2011

AbstractGrowing concerns surrounding established and expanding populations of wild pigs (Sus scrofa) have created the need for rapid and accurate surveys of these populations. We conducted surveys of a portion of the wild pig population on Fort Benning, Georgia, to determine if a longer time‐lapse interval than had been previously used in surveys of wild pigs would generate similar detection results. We concurrently examined whether use of soured corn at camera sites affected the time necessary for pigs to locate a new camera site or the time pigs remained at a site. Our results suggest that a 9‐min time‐lapse interval generated dependable detection results for pigs and that soured corn neither attracted pigs to a site any quicker than plain, dry, whole‐kernel corn, nor held them at a site longer. Maximization of time‐lapse interval should decrease data and processing loads, and use of a simple, available bait should decrease cost and effort associated with more complicated baits; combination of these concepts should increase efficiency of wild pig surveys. © 2011 The Wildlife Society.
Grassland birds and rotational‐grazing in the northeast: Breeding ecology, survival and management opportunities
Authors: Perlut Noah G. , Strong Allan M. 
Published: May 2011

AbstractWe studied long‐term (2002–2009) demographics of bobolinks (Dolichonyx oryzivorus) and savannah sparrows (Passerculus sandwichensis) breeding in rotationally grazed systems in the northeastern United States. Both nest success (6–44% bobolink; 7–48% savannah sparrow) and annual productivity (0.43–2.83 bobolink; 0.70–2.35 savannah sparrow) varied annually. Predation (48%) and trampling by cows (32%) accounted for most failed nests. Annual adult apparent survival ranged from 23% to 85% and showed substantial variation by species and sex. Although grazing resulted in substantial loss of vegetative cover, savannah sparrows responded similarly to predation and grazing‐induced nest failure (time to renest, distance moved between nests) and generally remained in the same paddock to renest. Minimum paddock size to accommodate one female within this rotation was 70 m × 70 m (0.49 ha), allowing a female to stay within a paddock and move (approx. 50 m) between nesting attempts. To balance pasturing objectives and birds' needs in paddocks first grazed before 25 June, managers in the Northeast should rest that paddock 42–50 days before the second grazing. © 2011 The Wildlife Society.
Barred owl occupancy surveys within the range of the northern spotted owl
Authors: Wiens J. David , Anthony Robert G. , Forsman Eric D. 
Published: May 2011

AbstractThe range expansion by barred owls (Strix varia) into western North America has raised considerable concern regarding their potential effects on declining northern spotted owl (Strix occidentalis caurina) populations, yet most information on the occurrence of barred owls in the region is limited to incidental detections during surveys for spotted owls. To address this shortcoming we investigated response behavior, detection probabilities, and landscape occupancy patterns of barred owls in western Oregon, USA, during conspecific versus spotted owl call‐broadcast surveys. Subtle differences in barred owl response behavior to conspecific versus spotted owl vocalizations combined with minor procedural differences between species‐specific survey protocols led to a sizeable difference in estimated detection probabilities during conspecific (0.66, 95% CI = 0.61–0.71) versus spotted owl (0.48, 95% CI = 0.39–0.56) surveys. We identified 61 territorial pairs of barred owls during repeated surveys of a multi‐ownership study area with the probability of occupancy being highest in the structurally diverse mixture of mature and old forests that occurred almost entirely on public lands. Our findings suggest that research and management strategies to address potential competitive interactions between spotted owls and barred owls will require carefully designed, species‐specific survey methods that account for erratic response behaviors and imperfect detection of both species. Our sampling methods can be used by forest managers to determine the occurrence and distribution of barred owls with high confidence. © 2011 The Wildlife Society.
Influence of fruit on habitat selection of Asian bears in a tropical forest
Authors: Ngoprasert Dusit , Steinmetz Robert , Reed David H. , Savini Tommaso , Gale George A. 
Published: May 2011

AbstractWild bear populations in Southeast Asia are threatened with extinction, but the ecology and distribution of the 2 species occurring in the region's protected areas is poorly known, so there is little scientific basis underlying conservation strategies. We used bear signs, primarily claw marks on climbed trees, to study habitat selection and distribution of Asiatic black bear (Ursus thibetanus) and sun bear (Helarctos malayanus) across Khao Yai National Park, Thailand from March to December 2008. We found black bear claw marks in 24 of 30 random sample blocks (80%), indicating that this species was widely distributed across Khao Yai. Sun bear signs were much scarcer: their claw marks occurred in 11 blocks (37%); data were too sparse for sun bear so we limited our focus to Asiatic black bear. Using logistic regression, we found that fruit abundance best explained variation in presence of black bear, whereas human disturbance, distance to park edge, elevation, and ground cover had little influence. Fruits appear to be a key resource for Asiatic black bears, and factors affecting fruit abundance or shifts in seasonality (e.g., climate change) will impact bear populations. Knowledge of this relationship will allow managers to be more proactive in managing bears. We recommend using sign surveys for monitoring changes in black bear occupancy as they are inexpensive, efficient, and can be conducted by trained park rangers. © 2011 The Wildlife Society.
Seeking parsimony in landscape metrics
Authors: Cunningham Mary Ann , Johnson Douglas H. 
Published: May 2011

AbstractNumerous metrics describing landscape patterns have been used to explain landscape‐scale habitat selection by birds. The myriad metrics, their complexity, and inconsistent responses to them by birds have led to a lack of clear recommendations for managing land for desired species. The amount of a target land cover type in the landscape (percentage cover) often has been a useful indicator of the likelihood of species occurrence or of habitat selection; is it also a more adequate and parsimonious measure for explaining species distributions than patch size or more complex measures of landscape configuration? We examined responses of 6 woodland‐interior bird species to the percentage tree cover within prescribed areas and to patch size, edge density, and other metrics. We examined responses in 2 landscapes: a mixed woodland‐savanna and an eastern deciduous forest. For these 6 species, percentage tree cover explained bird occurrence as well as or better than other measures in both study areas. We then repeated the analysis on a larger group of woodland species, including those associated with woodland edges. The bird species we studied had varied responses to landscape metrics, but percentage tree cover was the strongest explanatory variable overall. Although percentage cover estimated from remotely sensed data is an inexact representation of habitat in the landscape, it does appear to be reliable and easy to conceptualize, relative to other measures. We suggest that, at least for woodland habitat, percentage cover is a broadly useful measure that can be helpful in pragmatic questions of explaining responses to landscapes or in anticipating responses to landscape change. © 2011 The Wildlife Society.
Decision analysis for conservation breeding: Maximizing production for reintroduction of whooping cranes
Authors: Smith Des H.V. , Converse Sarah J. , Gibson Keith W. , Moehrenschlager Axel , Link William A. , Olsen Glenn H. , Maguire Kelly 
Published: May 2011

AbstractCaptive breeding is key to management of severely endangered species, but maximizing captive production can be challenging because of poor knowledge of species breeding biology and the complexity of evaluating different management options. In the face of uncertainty and complexity, decision‐analytic approaches can be used to identify optimal management options for maximizing captive production. Building decision‐analytic models requires iterations of model conception, data analysis, model building and evaluation, identification of remaining uncertainty, further research and monitoring to reduce uncertainty, and integration of new data into the model. We initiated such a process to maximize captive production of the whooping crane (Grus americana), the world's most endangered crane, which is managed through captive breeding and reintroduction. We collected 15 years of captive breeding data from 3 institutions and used Bayesian analysis and model selection to identify predictors of whooping crane hatching success. The strongest predictor, and that with clear management relevance, was incubation environment. The incubation period of whooping crane eggs is split across two environments: crane nests and artificial incubators. Although artificial incubators are useful for allowing breeding pairs to produce multiple clutches, our results indicate that crane incubation is most effective at promoting hatching success. Hatching probability increased the longer an egg spent in a crane nest, from 40% hatching probability for eggs receiving 1 day of crane incubation to 95% for those receiving 30 days (time incubated in each environment varied independently of total incubation period). Because birds will lay fewer eggs when they are incubating longer, a tradeoff exists between the number of clutches produced and egg hatching probability. We developed a decision‐analytic model that estimated 16 to be the optimal number of days of crane incubation needed to maximize the number of offspring produced. These results show that using decision‐analytic tools to account for uncertainty in captive breeding can improve the rate at which such programs contribute to wildlife reintroductions. © 2011 The Wildlife Society.
Assessing release protocols for Canada lynx reintroduction in colorado
Authors: Devineau Olivier , Shenk Tanya M. , Doherty Paul F. , White Gary C. , Kahn Rick H. 
Published: May 2011

AbstractReintroductions are a common strategy to restore ecosystem integrity, especially when top predators are involved. Reintroductions are often time consuming, expensive, and controversial, and thus understanding what aspects are important for a successful program is needed. Focusing on the example of the reintroduction of Canada lynx (Lynx canadensis) to Colorado, we investigated how different release protocols (RP) affected mortality within the first year post‐release. We found that average monthly mortality in the study area during the first year decreased with time in captivity from 0.205 (95% CI = 0.069, 0.475) for lynx having spent up to 7 days in captivity to 0.028 (95% CI = 0.012, 0.064) for lynx spending >45 days in captivity before release. Our results also suggest that keeping lynx in captivity beyond 5–6 weeks accrued little benefit in terms of monthly survival. We found that, on a monthly average basis, lynx were as likely to move out (P = 0.196, SE = 0.032) as well as back onto (P = 0.143, SE = 0.034) the reintroduction area during the first year after release. Mortality was 1.6 times greater outside of the study area, suggesting that permanent emigration and differential mortality rates on and off reintroduction areas should be factored into sample size calculations for an effective reintroduction effort. A post‐release monitoring plan is critical to providing information to assess aspects of RP and to improve survival of individuals. Future lynx and other carnivore reintroductions may use our results to help design reintroduction programs including both the release and post‐release monitoring protocols. © 2011 The Wildlife Society.
Effects of satellite transmitters fitted to breeding Cory's shearwaters
Authors: Villard Pascal , Bonenfant Christophe , Bretagnolle Vincent 
Published: May 2011

AbstractWe studied the effects of a new technique to fix satellite transmitters on the feeding behavior and chick body growth of the Cory's shearwater (Calonectris diomedea). Transmitters did not significantly affect the breeding bird's body mass or diving performance. However, on average, pairs with ≥1 adult equipped with a transmitter brought a lighter meal (54.8 ± 18.9 g) to nestlings than did control birds or the same pair with the transmitter removed (77.4 ± 8.3 g) leading to a decreased chick body growth. However at fledging, chicks in control and treatment groups had similar body mass whether parents were equipped with a PTT or not. Our method of transmitter attachment could therefore be an appropriate alternative for studying the ecology of procellariiforms weighing <1 kg given that birds are fitted with transmitters for <2 weeks and restricted to 1 parent only. © 2011 The Wildlife Society.
Implications of ignoring telemetry error on inference in wildlife resource use models
Authors: Montgomery Robert A. , Roloff Gary J. , Hoef Jay M. Ver 
Published: May 2011

AbstractGlobal Positioning System (GPS) and very high frequency (VHF) telemetry data redefined the examination of wildlife resource use. Researchers collar animals, relocate those animals over time, and utilize the estimated locations to infer resource use and build predictive models. Precision of these estimated wildlife locations, however, influences the reliability of point‐based models with accuracy depending on the interaction between mean telemetry error and how habitat characteristics are mapped (categorical raster resolution and patch size). Telemetry data often foster the assumption that locational error can be ignored without biasing study results. We evaluated the effects of mean telemetry error and categorical raster resolution on the correct characterization of patch use when locational error is ignored. We found that our ability to accurately attribute patch type to an estimated telemetry location improved nonlinearly as patch size increased and mean telemetry error decreased. Furthermore, the exact shape of these relationships was directly influenced by categorical raster resolution. Accuracy ranged from 100% (200‐ha patch size, 1‐ to 5‐m telemetry error) to 46% (0.5‐ha patch size, 56‐ to 60‐m telemetry error) for 10 m resolution rasters. Accuracy ranged from 99% (200‐ha patch size, 1‐ to 5‐m telemetry error) to 57% (0.5‐ha patch size, 56‐ to 60‐m telemetry error) for 30‐m resolution rasters. When covariate rasters were less resolute (30 m vs. 10 m) estimates for the ignore technique were more accurate at smaller patch sizes. Hence, both fine resolution (10 m) covariate rasters and small patch sizes increased probability of patch misidentification. Our results help frame the scope of ecological inference made from point‐based wildlife resource use models. For instance, to make ecological inferences with 90% accuracy at small patch sizes (≤5 ha) mean telemetry error ≤5 m is required for 10‐m resolution categorical rasters. To achieve the same inference on 30‐m resolution categorical rasters, mean telemetry error ≤10 m is required. We encourage wildlife professionals creating point‐based models to assess whether reasonable estimates of resource use can be expected given their telemetry error, covariate raster resolution, and range of patch sizes. © 2011 The Wildlife Society.
Separation of asymmetric triacylglycerols into their enantiomers by recycle high‐performance liquid chromatography
Authors: Gotoh Naohiro , Wada Shun , Nagai Toshiharu 
Published: May 2011

AbstractA recycle HPLC system equipped with a polysaccharide‐based chiral column was used for the enantiomeric separation of asymmetric triacylglycerols (TAGs). When the chiral columns were screened by the resolution of 1,2‐dipalmitoyl‐3‐oleoyl‐rac‐glycerol separation was achieved only with the cellulose tris‐ (3,5‐dimethylphenylcarbamate) chiral selector. The resolution of other TAG enantiomers was also examined, and 1,2‐dioleoyl‐3‐palmitoyl‐rac‐glycerol, 1,2‐dipalmitoyl‐3‐linoleoyl‐rac‐glycerol, 1,2‐dipalmitoyl‐3‐eicosapentaenoyl‐rac‐glycerol, 1,2‐dipalmitoyl‐3‐docosahexaenoyl‐rac‐glycerol, and 1,2‐docosahexaenoyl‐3‐palmitoyl‐rac‐glycerol were resolved into their respective enantiomers. However, neither 1,2‐dioleoyl‐3‐linoleoyl‐rac‐glycerol, consisting of only unsaturated fatty acids, nor 1,2‐dipalmitoyl‐3‐stearoyl‐rac‐glycerol, consisting of only saturated fatty acids, was resolved. In addition, 1,2‐eicosapentaenoyl‐3‐palmitoyl‐rac‐glycerol was not resolved clearly, even in the recycle runs. These results suggest that asymmetric TAGs having both a palmitic acid moiety and an unsaturated fatty acid moiety at the sn‐1 or sn‐3 positions might be resolved on a cellulose tris‐ (3,5‐dimethylphenylcarbamate) chiral column.