We perceive a need for more complete interpretation of regression models published in the wildlife literature to minimize the appearance of poor models and to maximize the extraction of information from good models. Accordingly, we offer this primer on interpretation of parameters in single- and multi-variable regression models. Using examples from the wildlife literature, we illustrate how to interpret linear zero-intercept, simple linear, semi-log, log-log, and polynomial models based on intercepts, coefficients, and shapes of relationships. We show how intercepts and coefficients have biological and management interpretations. We examine multiple linear regression models and show how to use the signs ( , −) of coefficients to assess the merit and meaning of a derived model. We discuss 3 methods of viewing the output of 3-dimensional models (y, x₁, x₂) in 2-dimensional space (sheet of paper) and illustrate graphical model interpretation with a 4-dimensional logistic regression model. Statistical significance or Akaike best-ness does not prevent the appearance of implausible regression models. We recommend that members of the peer review process be sensitive to full interpretation of regression models to forestall bad models and maximize information retrieval from good models

The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, and Lasiurus cinereus) in Whiskeytown National Recreation Area in north-central California, USA. We used landscape-scale variables, logistic regression, and Akaike's Information Criterion (AIC_c) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape-scale variables best discriminated between capture sites and non-capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver-haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver-haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver-haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.

Migratory birds wintering at the same location are usually coming from populations of different origins, in variable proportions. Using data from individuals banded on their wintering grounds and recovered on their breeding areas, we show that such proportions are estimable given that 1) all breeding populations are identified, and 2) the wintering population can be stratified into ≥1 more site than the number of breeding populations. We applied this technique to woodcock (Scolopax rusticola) banded while wintering in France (N = 35,000) and recovered in other European countries (N = 520). We estimated that the proportion of eastern woodcock among those wintering in France varied spatially, ranging from 70% in northwest France to nearly 100% in southeast France, and increased substantially over the last 15 years. Overall, the method appears powerful to quantify spatial variation of the composition of a population receiving individuals from various origins.

Although previous research and theory has suggested that wild turkey (Meleagris gallopavo) populations may be subject to some form of density dependence, there has been no effort to estimate and incorporate a density-dependence parameter into wild turkey population models. To estimate a functional relationship for density dependence in wild turkey, we analyzed a set of harvest-index time series from 11 state wildlife agencies. We tested for lagged correlations between annual harvest indices using partial autocorrelation analysis. We assessed the ability of the density-dependent theta-Ricker model to explain harvest indices over time relative to exponential or random walk growth models. We tested the homogeneity of the density-dependence parameter estimates (θ) from 3 different harvest indices (spring harvest no. reported harvest/effort, survey harvest/effort) and calculated a weighted average based on each estimate's variance and its estimated covariance with the other indices. To estimate the potential bias in parameter estimates from measurement error, we conducted a simulation study using the theta-Ricker with known values and lognormally distributed measurement error. Partial autocorrelation function analysis indicated that harvest indices were significantly correlated only with their value at the previous time step. The theta-Ricker model performed better than the exponential growth or random walk models for all 3 indices. Simulation of known parameters and measurement error indicated a strong positive upward bias in the density-dependent parameter estimate, with increasing measurement error. The average density-dependence estimate, corrected for measurement error ranged 0.25 ≤ θ̂ ≤ 0.49, depending on the amount of measurement error and assumed spring harvest rate. We infer that density dependence is nonlinear in wild turkey, where growth rates are maximized at 39–42% of carrying capacity. The annual yield produced by density-dependent population growth will tend to be less than that caused by extrinsic environmental factors. This study indicates that both density-dependent and density-independent processes are important to wild turkey population growth, and we make initial suggestions on incorporating both into harvest management strategies.

Mammalian females change their behavior during the last stages of pregnancy and during the weaning as a response to new energetic requirements and antipredator behavior. From March 2001 to December 2004, we studied the effects of parturition and weaning on home-range sizes and habitat selection in 28 female Alpine ibex (Capra ibex) in a 1,700-ha free area in the Gran Paradiso National Park (Western Italian Alps). We calculated Kernel home range enclosing 95% of each female's locations according to seasonal and bimonthly timescales. Pregnancy did not seem to modify spatial behavior. Lactating females showed smaller home ranges than nonlactating ones after the birth period in June–July. Hot summers slowed kids' growth and prolonged maternal care, modifying mothers' behavior. In summer 2003, which was hotter and drier than usual, weaning females showed even smaller home ranges. Because of their use of antipredator tactics during the weaning season, lactating females showed a higher use of safer habitats, such as rocky slopes. Our results are consistent with the findings of previous cervid and bovid studies, and they suggest that ungulate mothers may move to suboptimal, but safer, habitats during weaning to reduce the predation risk for their offspring.

We investigated reproductive ecology and cub survival of Florida black bears (Ursus americanus floridanus) in Ocala National Forest and the adjacent residential area of Lynne, Florida, USA, 1999–2003. We documented production of 81 cubs from 39 litters. Average litter size was 2.08 ± 0.11 (SE) cubs. The mean age of first reproduction was 3.25 ± 0.27 years. Excluding females that reproduced in consecutive years due to litter loss, interlitter interval was 2.11 ± 0.11 years. The mean annual fecundity rate was 0.57 ± 0.06. We used expandable radiocollars to monitor the fate of 41 bear cubs. The probability of cubs surviving to 9 months of age was 0.46 ± 0.09 and did not differ between cohorts or study locations. The most important causes of cub mortality included infanticide and mortality caused directly or indirectly by collisions with vehicles. Our results indicate that reproductive rates of female black bears in the Ocala study area are comparable to those reported for other black bear populations from eastern United States, but cub survival rates are lower than those reported for most black bear populations. Management of Florida black bears should emphasize strategies to reduce the mortality of cubs.

Despite prevalent use of anthropogenic structures by bats and the associated implications for public health, management, and bat conservation, very little quantitative information exists about urban roost characteristics and their selection by bats. During the summers of 2001 to 2004 we conducted fieldwork in Fort Collins, Colorado, USA, situated on the northern end of Colorado's Front Range, to address questions of roost selection by the big brown bat (Eptesicus fuscus). The city has experienced its greatest growth in the past half century, with its population increasing by 30% in the last decade. Similar growth in new buildings has occurred, with the number of new housing permits issued annually doubling in the past decade. We located 142 roosts using radiotelemetry or by citizen calls in response to a newspaper article and flyers. To determine characteristics of roost selectivity by bats, we compared variables for known maternity roosts and randomly selected buildings at microhabitat and landscape scales using logistic regression; we used an information theoretic approach to determine which variables were most important. We considered 44 and 100 buildings in the microhabitat and landscape scale analyses, respectively. At the microhabitat scale maternity roosts had exit points with larger areas that were higher from the ground and had warmer average temperatures than randomly selected buildings. At the landscape scale distances to similarly categorized roosts were smaller, and urbanization variables such as lower building density, higher street density, and lower traffic count density were most important. Results for variables important to urban-roosting big brown bats were often analogous to studies that characterized maternity roosts found in tree snags and rock crevices. In addition, changes in the landscape, not only in the form of anthropogenic structures but also in water availability and vegetation structure such as riparian forests, may have led to population increases and range expansions of the big brown bat. Because big brown bats appear to selectively choose specific combinations of characteristics found at maternity roosts, not all available structures can be considered suitable and exclusion from established maternity roosts may negatively impact bat populations.

Survival and cause-specific mortality of pronghorns (Antilocapra americana) have been well-documented in several western states and Canadian provinces. However, no information has been collected in western South Dakota, USA, where mixed-grass prairie habitats characterize rangelands. The objectives of our study were to determine survival and cause-specific mortality of adult (>18 months) and yearling (6–18 months) pronghorns and to determine monthly and summer (Jun–Aug) survival for neonatal (<1 month of age) pronghorns in South Dakota. We radiocollared 93 adult female and 142 neonatal pronghorns on 3 areas in western South Dakota. We used bed sites from initial neonate captures to collect microhabitat information throughout Harding and Fall River counties. We measured vegetation understory and overstory height, shrub canopy, and distance to nearest concealment cover to the nearest centimeter inside 1-m² quadrats by collecting measurements at 15 random points within a 30-m radius of the bed site. We documented that coyote (Canis latrans) predation was the primary cause of mortality for neonates in western South Dakota and that microhabitat characteristics at neonate bed sites differed between northwestern and southwestern South Dakota. More intensive aerial predator control may increase neonate survival in Fall River County. Management of rangelands by state and federal employees throughout western South Dakota and Wind Cave National Park that maximizes height of overstory and understory vegetation would provide neonates with adequate concealment cover for protection from predators, thereby increasing 4-week and 12-week postcapture survival. Our study provides South Dakota game managers with region-specific, annual and seasonal survival rates that were previously only estimated, thus improving the accuracy of simulated pronghorn population model output. Hunting was the primary cause of mortality (26%) for adult females in Harding and Fall River counties, thereby confirming the continued use of annual harvest by South Dakota game managers as the primary management tool for maintaining pronghorn populations within statewide population management goals.

Intensive pine (Pinus spp.) management is a dominant form of forest management in the southeastern United States. Previous research has shown that managed pine forests provide suitable habitat for eastern wild turkeys (Meleagris gallopavo silvestris), but little research has examined seasonal habitat selection for female wild turkeys from a landscape perspective, particularly within managed pine landscapes. Therefore, we used a long-term (1986–1993) data set to describe seasonal habitat selection by female wild turkeys, using an information-theoretic approach from a landscape perspective, on an intensively managed pine landscape. Habitat use patterns during preincubation and autumn–winter were indicative of female wild turkeys moving between a bottomland hardwood–agricultural field complex during autumn–winter and upland managed pine stands during the remainder of the year. During spring and summer, female wild turkeys used landscapes primarily composed of intensively managed pine, including thinned and burned stands and roadsides. Our results confirm results of short-term, stand-based habitat analyses on our study area. We recommend variable fire return intervals of 3 to 7 years to improve habitat conditions for wild turkeys within intensively managed pine forests. Further research is needed to examine management actions, such as thinning, prescribed fire, and herbicide use, within the context of wild turkey use of intensively managed pine landscapes.

Although moss is commonly found in the feces of arctic herbivores, we do not know the digestible value of this forage for ruminants. We compared grass hay (Bromus sp.) with moss (Hylocomium splendens, Tomenthypnum nitens) from 2 locations in Alaska, USA: Cape Krusenstern National Monument and Fairbanks. We evaluated forages by digestion in ruminally fistulated muskoxen (Ovibos moschatus) by suspending forages in polyester bags before and after the rumen was acclimated with moss for 15 consecutive days. Ruminal degradation was not affected by acclimation to moss. Hay lost dry matter during 48 hours of ruminal incubation (−49%), whereas moss gained dry matter ( 44–57%). Incubated moss gained nitrogen ( 435–680%), as well as fiber ( 18%), and one moss gained ash ( 121%). Mass gained by moss in the rumen was probably due to the combined effect of microbial colonization and adsorption of fibrous particles onto the sponge-like matrix. We evaluated postruminal degradation of forages by incubation in acid-pepsin. Ruminally incubated mosses lost little nitrogen in acid-pepsin even though ruminally incubated hay lost 23% nitrogen on acid digestion. Consumption of moss during winter may be a net cost of selecting plants within moss communities when lichens and graminoids are scarce. Moss in feces may, therefore, indicate low availability of favored foods for muskoxen and other arctic ruminants that are confined to small winter ranges. Increasing concentrations of moss in the feces and, thus, the diet of muskoxen may alert wildlife managers to shifts in winter range quality or forage access due to changing snow conditions.

The eastern diamondback rattlesnake (Crotalus adamanteus) and timber rattlesnake (Crotalus horridus) are sympatric throughout most of southern Georgia, USA. We used rattlesnake sightings to quantify and compare habitat use by these 2 species in the Gulf Coastal Plain. At the largest scale examined, univariate statistics and logistic regression models indicated that eastern diamondback rattlesnakes were associated with roads but not with any of the specific habitat types we examined. In contrast, timber rattlesnakes were closely associated with hardwood habitat and riverine systems but not with roads and edges. To effectively conserve and manage both species in the Southeast, a habitat matrix of large intact patches of both hardwood and pine (Pinus spp.) forest may be necessary.

Information about the interaction between behavior and landscape resources is key to directing conservation management for endangered species. We studied multi-scale occurrence, habitat use, and selection in a cooperatively breeding population of Micronesian kingfishers (Todiramphus cinnamominus) on the island of Pohnpei, Federated States of Micronesia. At the landscape level, point-transect surveys resulted in kingfisher detection frequencies that were higher than those reported in 1994, although they remained 15–40% lower than 1983 indices. Integration of spatially explicit vegetation information with survey results indicated that kingfisher detections were positively associated with the amount of wet forest and grass–urban vegetative cover, and they were negatively associated with agricultural forest, secondary vegetation, and upland forest cover types. We used radiotelemetry and remote sensing to evaluate habitat use by individual kingfishers at the home-range scale. A comparison of habitats in Micronesian kingfisher home ranges with those in randomly placed polygons illustrated that birds used more forested areas than were randomly available in the immediate surrounding area. Further, members of cooperatively breeding groups included more forest in their home ranges than birds in pair-breeding territories, and forested portions of study areas appeared to be saturated with territories. Together, these results suggested that forest habitats were limited for Micronesian kingfishers. Thus, protecting and managing forests is important for the restoration of Micronesian kingfishers to the island of Guam (United States Territory), where they are currently extirpated, as well as to maintaining kingfisher populations on the islands of Pohnpei and Palau. Results further indicated that limited forest resources may restrict dispersal opportunities and, therefore, play a role in delayed dispersal and cooperative behaviors in Micronesian kingfishers.

Incomplete population counts indicate change in population sizes when constant proportionality holds, a condition that is rarely met. However, researchers have not explored whether constant proportionality holds for a segment of a population. I examined whether the female segment (juv, subadult M, subadult and ad F) of a Roosevelt elk (Cervus elaphus roosevelti) population displayed constant proportionality. When most food is in particular habitats, females of polygynous species should use that habitat frequently, even when food is limited, because they are more familiar with food distribution and abundance than males. I obtained counts of elk and tallies of naturally marked animals from vehicle surveys of a population inhabiting a landscape where forage was in meadows that were interspersed in closed-canopied forest. I conducted population surveys in January or February and estimated population size with Bowden's mark–resight estimator. Population size estimates declined from 130 in 1997 to 37 in 2006. The proportion of the population counted during surveys was inversely related to population size estimates. Estimated population sizes were inversely related to male (r² = 0.56) but not female sighting probabilities (r² = 0.004), which were ≥0.9. Constant proportionality in counts held for only the female segment of the population. Counts of the female segment of the population can inform managers about changes in this segment of the population over time.

The combined lesser scaup (Aythya affinis) and greater scaup (A. marila) population in North America has steadily declined from an average of 7.5 million breeding birds in the 1970s to an all-time low of 3.39 million in 2005. Bioaccumulation is widely known as the means of elevated levels of toxins in vertebrates. Our goal was to determine whether chromium and selenium were factors contributing to the continental scaup population decline by identifying wetlands used by scaup that potentially contain dangerous concentrations of chromium and selenium. We hypothesized that zebra mussels (Dreissena polymorpha) would contain the highest concentrations of selenium and chromium because they are filter feeders, whereas amphipods would contain the lowest concentrations because of their short life span. We collected zebra mussels, fingernail clams (Sphaerium transversum), chironomid larvae, snails (Gastropoda), and amphipods on randomly selected traditional lesser scaup staging and breeding wetlands. We found higher chromium concentrations in zebra mussels from Iowa, USA, than in those from Wisconsin, USA (P = 0.0074). In addition, selenium concentrations in zebra mussels from Wisconsin were higher than in those from Iowa (P < 0.0001). Higher selenium concentrations in amphipods were associated with sampled wetlands surrounded by developed land. Invertebrates with >5 μg/g selenium and >1 μg/g chromium are potentially hazardous for scaup. Chromium concentrations in Iowa were the highest for most species examined, whereas they were the lowest in Minnesota, USA. Based on our results, lesser scaup probably accumulate the highest concentrations of selenium on Lake Onalaska, Wisconsin, whereas they probably accumulate the lowest concentrations in Iowa. Waterfowl biologists are searching for explanations to the scaup decline; we propose chromium and selenium concentrations in amphipods and fingernail clams may be a factor.

Relocations of gopher tortoises (Gopherus polyphemus) in Florida, USA, are frequently employed as mitigation tools when tortoises occupy land desired for development. Here we present information about retention and health of a relocated population of gopher tortoises 17 years after relocation. We combine our 17-year postrelocation data with earlier surveys 1 year and 2 years postrelocation to examine whether retention rates change over time. We also evaluate whether retention rates vary by age and gender. Of 74 gopher tortoises relocated in 1985, 31 were present in 2002. We found a 1-year retention rate of 42%, with retention rates of 100% each year thereafter, when we used the percentage of relocated individuals captured at each survey. We found a 1-year retention rate of 73%, a retention rate of 92% from year 1 to year 2, and an overall retention rate of 98.5% from year 2 through year 17, based on the assumption that all individuals present in later surveys were present in earlier surveys. We found no significant difference in retention rate over the 17-year period for adults and juveniles and for adult males and females. Relocated gopher tortoises showed natural growth patterns, indicating good health, but 35% of these gopher tortoises had ≥1 symptom of upper respiratory tract disease, a disease associated elsewhere with population declines of tortoises. Thus, retention rates of relocated gopher tortoises change over time, with relatively low retention during the first year postrelocation but nearly 100% retention in subsequent years. In general, our study shows that relocations can successfully lead to long-term retention of gopher tortoises, but we predict that without management (e.g., fire management and predator control) this relocated population is not viable.

Well known for a fall spectacle of maturing wild rice (Zizania aquatica) and migrant waterbirds, the tidal freshwater marshes of the Patuxent River, Maryland, USA, experienced a major decline in wild rice during the 1990s. We conducted experiments in 1999 and 2000 with fenced exclosures and discovered herbivory by resident Canada geese (Branta canadensis). Grazing by geese eliminated rice outside exclosures, whereas protected plants achieved greater size, density, and produced more panicles than rice occurring in natural stands. The observed loss of rice on the Patuxent River reflects both the sensitivity of this annual plant to herbivory and the destructive nature of an overabundance of resident geese on natural marsh vegetation. Recovery of rice followed 2 management actions: hunting removal of approximately 1,700 geese during a 4-year period and reestablishment of rice through a large-scale fencing and planting program.

The realized impact of a vital rate on population growth (λ) is determined by both the relative influence of the vital rate on λ (elasticity) and its magnitude of variability. We estimated mean survival and reproductive rates in elk (Cervus elaphus) and spatial and temporal variation in these rates from 37 sources located primarily across the Rocky Mountain region and northwestern United States. We removed sampling variance from estimates of process variance both within and across vital-rate data sets using the variance discounting method developed by White (2000). Deterministic elasticities calculated from a population matrix model parameterized with these mean vital rates ranked adult female survival (e_Scow = 0.869) much higher than calf survival (e_Scalf = 0.131). However, process variance in calf survival (σ̂²_Scalf = 0.039) was >11 times greater than process variance in female survival (σ̂²_Scow = 0.003) across data sets and 10 times greater on average (²_Scalf = 0.020; ²_Scow = 0.002) within studies. We conducted Life-Stage Simulation Analysis to incorporate both vital-rate elasticity patterns and empirical estimates of variability to identify those vital rates most influential in elk population dynamics. The overwhelming magnitude of variation in calf survival explained 75% of the variation in the population growth rates generated from 1,000 matrix replicates, compared to just 16% of the variation in λ explained by variation in female survival. Variation in calf survival greatly impacts elk population growth and calls into question the utility of classical elasticity analysis alone for guiding elk management. These results also suggest that the majority of interannual variability that wildlife managers document in late-winter and spring elk surveys is attributable to variation in calf survival over the previous year and less influenced by variation in the harvest of females during the preceding autumn. To meet elk population size objectives, managers should consider the inherent variation in calf survival, and its apparent sensitivity to management, in addition to female harvest.

Ecologically based management must incorporate components that consider how individuals associate temporally and spatially to environments that provide specific habitat requirements. Recent research has assessed how environments could be classified based on potential to provide deer (Odocoileus virginianus) habitat components. If habitat potential (HP; i.e., capability of habitat types to provide annual life requisites) classifications can be correlated to deer spatial structure and seasonal movement patterns, managers could better understand how spatial distribution of habitat components influences deer distribution. We analyzed home-range distribution and seasonal movement patterns from 45 adult (≥2 yr old) female deer radiocollared between 1999–2002, and deer habitat characteristics in northeastern Lower Peninsula, Michigan, USA, to investigate whether we can predict deer seasonal movement patterns based on the distribution of HP. We constructed logistic regression models that calculated the probability of deer migration given specific HP within seasonal home ranges of migratory and nonmigratory deer. Our results suggested that the probability of seasonal deer migrations relates to the juxtaposition (arrangement) of different habitat types that collectively provide all annual life requisites. We demonstrated that use of habitat-type classifications and HP models can track and predict deer movement patterns, which can facilitate establishment of management units and ecologically based deer management practices.

Some diurnal raptors are frequently observed at prairie dog (Cynomys sp.) colonies. As a result, some military installations have conducted prairie dog control activities to reduce the bird–aircraft strike hazard (BASH) potential of low-flying aircraft. To evaluate the validity of this management strategy, we assessed raptor associations with prairie dog colonies at 2 short-grass prairie study areas: southern Lubbock County, Texas, USA, and Melrose Bombing and Gunnery Range in east-central New Mexico, USA. We quantified diurnal raptors (i.e., Falconiformes) at plots occupied (colony plots) and unoccupied (noncolony plots) by black-tailed prairie dogs (Cynomys ludovicianus) at both sites throughout 2002. We compared the number of individual birds of a given species at colony and noncolony plots within each study area by season. Ferruginous hawks (Buteo regalis) and northern harriers (Circus cyaneus) were more abundant at colony plots, whereas Swainson's hawks (B. swainsoni) and American kestrels (Falco sparverius) were more abundant at noncolony plots. Red-tailed hawk (B. jamaicensis) abundance did not differ between the 2 plot types. Our results suggest prairie dog control as a method of reducing BASH potential may be effective at some sites but may be ineffective or even increase the BASH potential at others. Thus, bird-avoidance models assessing the BASH potential should be conducted on a site-specific basis using information on relative and seasonal abundances of individual raptor species and the relative strike risks they pose to aircraft.

We selected 2 adjacent populations of mule deer (Odocoileus hemionus hemionus) in the Bridger Mountains, Montana, USA, to measure effects on survival rates and causes of mortality of 2 hunting regulations designed to enhance representation of mature males. We compared male survival between the West Slope and South 16 Mile populations considering both hunting and nonhunting sources of mortality with respect to age (fawn, yearling, and mature), month (Jun–May), and year (1990–1995). Harvest rates of mature males were greater than for yearlings, demonstrating hunter preferences. We found no differences in yearling monthly survival rates between October and November or between areas or years. In contrast, we found survival of mature males differed between October and November and across years and study areas. During these months, survival rates of mature males averaged 0.602 on the West Slope under the 2-point regulation and 0.762 on South 16 Mile under the outfitted hunt. Monthly survival during summer also differed by age class, but not area, with estimates of 0.963 for yearling males, and corresponding mature male survival estimates of 0.991, demonstrating greater yearling summer mortality. Winter survival rates of yearlings and matures were similar for both areas with a monthly estimate of 0.986. We found differences in spring monthly survival estimates for the 2 areas, mainly for matures. Yearling male monthly survival estimates were 0.959 and 0.958 for the 2 areas, whereas corresponding mature male estimates during spring were 0.991 and 0.936 on the West Slope and South 16 Mile, respectively. Fawn survival rates varied from 0.101 to 0.770 among years and between areas overwinter. Cumulative effects of nonhunting mortality among all age classes reduced the effectiveness of 2 hunting regulations designed to enhance survival of males to age classes ≥4 years associated with maximum antler development despite accomplishing reductions in harvest rates. Low and variable fawn survival and relatively high nonhunting-related losses of yearling and mature males might be typical of many populations in the Northern Rocky Mountains. Deer managers should avoid populations coexisting with a diversity of large predators in environments with strong year effects when considering opportunities for implementing harvest regulations to improve representation of mature males.

We used an information-theoretic approach to investigate nest-site selection by black-capped vireos (Vireo atricapilla) at the landscape and habitat-patch scales on Fort Hood Military Reservation in central Texas, USA, during 2003 and 2004. We used a use–availability sampling design and logistic regression to compare woody cover characteristics at nests to random points in the landscape to determine habitat selection at the landscape scale. At the habitat-patch scale, we used matched case-control logistic regression to compare habitat measures at nests and random non-nest points to evaluate support for hypotheses concerning the influence of woody cover, nest-patch, and nest-site characteristics on black-capped vireo nest-site selection. At the landscape scale, we found strong support (Akaike wt [w_i] = 1.0) for a model with a cubic effect of percent woody cover and woody cover edge density. Sites with the greatest predicted probabilities of use had woody cover values between 30% and 60% and increasing amounts of edge. We found strong support (w_i = 0.93) for the global model at the habitat-patch scale that included characteristics of the nest site, nest patch, and woody cover within 25 m. Based on odds ratios and confidence limits, percent woody cover, cover below 2 m, cover type, and substrate height had the greatest effect on nest-site selection. The predicted probability a site was selected for a nest site increased with foliage cover below 2 m, taller substrates, deciduous cover, and decreased at high levels of percent woody cover (especially >80%). Texas red oak (Quercus buckleyi) was the most used nest substrate (100 of 358 nests), followed by shin oak (Q. sinuata var. breviloba; 86 of 358 nests) and Ashe juniper (Juniperus ashei; 44 of 358 nests). Black-capped vireos used Texas red oak and shin oak in greater proportion to their availability, whereas Ashe juniper was used less in proportion to its availability, suggesting vireos avoided this species. We suggest that managers promote dense deciduous cover for nesting habitat and maximize edge-to-area ratios to maintain spatial and structural heterogeneity.

Knowledge of the possible role of cyclic behavior in wildlife dynamics assists in understanding and managing populations. Using spectrum analysis, we analyzed time series (1978–2002) on the abundance of northern bobwhites (Colinus virginianus) and scaled quail (Callipepla squamata) in several ecological regions in Texas, USA, to test for the presence of cycles; we also tested whether drought severity (Modified Palmer Drought Severity Index) exhibited cyclic dynamics and whether quail and drought cycles were synchronized among regions. We found evidence of population cyclicity in all ecoregions we tested (5 for bobwhites, 4 for scaled quail) based on both Texas Parks and Wildlife and North American Breeding Bird Survey count data. Periods of the observed cycles generally were 5–6 years (bobwhites) or 2–3 years (scaled quail), depending on ecoregion and data source. Cyclicity was most pronounced for bobwhites in the Rolling Plains (north TX) and the South Texas Plains. The Palmer Index exhibited a roughly 5-year cycle in 5 of 6 regions we tested. A 5-year bobwhite and Palmer Index cycle were synchronous in 3 contiguous ecoregions totaling 27,200,000 ha. Wet–dry cycles seemed to synchronize bobwhite cycles in Texas. Our results suggest that habitat manipulations aimed at improving habitat conditions during dry periods, such as reducing livestock stocking rates, could provide ground cover similar to that available in wet periods.

For many wildlife species, agricultural landscapes undergo spatial and temporal fluctuations in the composition of food and cover annually with the planting and harvesting of crops. Raccoon (Procyon lotor) populations have flourished in agricultural landscapes, where crops increase foraging opportunities and efficiencies. However, information is lacking regarding the effects of temporal shifts in food and cover resulting from agricultural activities on raccoon home ranges. We examined home-range characteristics of 60 (33 M, 27 F) adult raccoons in northern Indiana, USA, from May 2003 through June 2005 to identify shifts in the size of home ranges and core use areas among seasons defined by crop availability and crop developmental stages. Mean fixed-kernel home-range (92 ± 6 ha; 𝑥̄ ± SE) and core-area sizes (20 ± 2 ha) of males were significantly larger than those of females (58 ± 7 ha and 13 ± 2 ha, respectively), and both were smaller than those reported for raccoons in other fragmented agricultural landscapes. Home-range sizes varied little among seasons for either sex. However, home ranges of males were smallest during the crop maturation stage, whereas home ranges of females were smallest during the crop growing season. The results of our study suggest that even in expansive rural landscapes, raccoons can maintain small home ranges when food, water, and denning resources are readily available. Additionally, the lack of differences among seasonal home-range sizes, despite the presence of an ephemeral superabundant food source (i.e., corn) during the maturation season, was likely due to the close proximity of foraging and denning resources across seasons.

Survival of white-tailed deer (Odocoileus virginianus) fawns has been quantified throughout much of North America. However, few studies have assessed the influence of intrinsic factors (e.g., fawn age and birth mass) and habitat on fawn survival. During 2002–2004, we captured and radiocollared 166 fawns in southern Illinois, USA, to estimate survival rates, determine causes of mortality, and identify factors influencing fawn survival. We used a known fates model in program MARK to estimate survival rates and compare explanatory models based on Akaike's Information Criterion corrected for small sample sizes (AIC_c). We developed 2 candidate sets of a priori models to quantify factors influencing fawn survival: model set 1 included intrinsic factors and model set 2 focused on habitat variables. We recorded 64 mortalities and the overall survival rate was 0.59 (95% CI = 0.51–0.68). Predation was the leading source of mortality (64%) and coyotes (Canis latrans) were the most prominent predator. For model set 1, model {S_age×year} had the lowest AIC_c value suggesting that the age at mortality varied among capture years. For model set 2, model {S_{landscape forest}} had the lowest AIC_c value and indicated that areas inhabited by surviving fawns were characterized by a few large (i.e., >5 ha) irregular forest patches adjacent to several small nonforest patches, and survival areas also contained more edge habitat than mortality areas. Due to the magnitude of coyote predation, survival areas could have represented landscapes where coyotes were less effective at locating and capturing fawns when compared to mortality areas. This study was the first account of macrohabitat characteristics directly influencing fawn survival. Wildlife managers can use this information to determine how habitat management activities may affect deer populations.

The white-cheeked pintail (Anas bahamensis) is listed as threatened, and survey data are needed to assess population status, estimate trends, and guide management on Puerto Rico and territorial islands. We surveyed 51 points in 29 wetland sites to estimate density and population size after the peak of reproduction (Mar–Jul) and before the waterfowl hunting season (Nov–Jan). Estimated density was 2.33 individuals/ha (SE = 0.27), and estimated population size was 3,755 individuals (SE = 435, log-normal 95% CI = 2,995 to 4,708) in 1,614 ha surveyed in August–October 2003–2005. Density differed between August–October 2003 (𝐷̂ = 3.07 individuals/ha, SE = 0.41) and 2004 (𝐷̂ = 1.26 individuals/ha, SE = 0.17) and between August–October 2004 and 2005 (𝐷̂ = 2.54 individuals/ha, SE = 0.47) but not between August–October 2003 and 2005. Spatial distribution ranged from nearly random (estimate of dispersion parameter [𝑏̂] = 0.99) to highly clumped (𝑏̂ = 3.71). We suggest that spatiotemporal variation of wetland hydrochemical conditions caused changes in foraging resources, which in turn caused changes in white-cheeked pintail density and spacing patterns. We recommend surveying 186 points 3 times in August–October for estimated density to have a coefficient of variation of 0.10, even when white-cheeked pintails are highly clustered (estimate of exp cluster size, Ê[s] = 16.1, SE = 2.8) and clumped (b = 4) in space. We provide additional recommendations for integrating monitoring, research, and management objectives to better understand the ecology and promote the conservation of white-cheeked pintails and their habitats locally and regionally.

Recent expansions by Rocky Mountain elk (Cervus elaphus) into nonforested habitats across the Intermountain West have required managers to reconsider the traditional paradigms of forage and cover as they relate to managing elk and their habitats. We examined seasonal habitat selection patterns of a hunted elk population in a nonforested high-desert region of southwestern Wyoming, USA. We used 35,246 global positioning system locations collected from 33 adult female elk to model probability of use as a function of 6 habitat variables: slope, aspect, elevation, habitat diversity, distance to shrub cover, and distance to road. We developed resource selection probability functions for individual elk, and then we averaged the coefficients to estimate population-level models for summer and winter periods. We used the population-level models to generate predictive maps by assigning pixels across the study area to 1 of 4 use categories (i.e., high, medium-high, medium-low, or low), based on quartiles of the predictions. Model coefficients and predictive maps indicated that elk selected for summer habitats characterized by higher elevations in areas of high vegetative diversity, close to shrub cover, northerly aspects, moderate slopes, and away from roads. Winter habitat selection patterns were similar, except elk shifted to areas with lower elevations and southerly aspects. We validated predictive maps by using 528 locations collected from an independent sample of radiomarked elk (n = 55) and calculating the proportion of locations that occurred in each of the 4 use categories. Together, the high- and medium-high use categories of the summer and winter predictive maps contained 92% and 74% of summer and winter elk locations, respectively. Our population-level models and associated predictive maps were successful in predicting winter and summer habitat use by elk in a nonforested environment. In the absence of forest cover, elk seemed to rely on a combination of shrubs, topography, and low human disturbance to meet their thermal and hiding cover requirements.

Wood ducks (Aix sponsa) and other species use tree cavities in forested wetlands and adjacent upland forests for nest sites and cover. The availability of tree cavities suitable for nesting is important to the population dynamics of hole-nesting species, but there is little quantitative information on how forest succession and maturation affect densities of suitable nest sites in eastern deciduous forests. Several studies have measured availability of tree cavities for nesting wood ducks, but data on cavity formation and persistence rates are needed to model changes in cavity abundance. We measured abundance and persistence of tree cavities suitable for nesting wood ducks in southern Illinois, USA, during 1993–2002. We simulated changes in abundance of nest cavities in the Mississippi River floodplain and adjacent upland forests using estimates of tree cavity densities by tree-diameter size classes and 10-year cavity persistence rates by tree species. Cavities were disproportionately common in the largest size classes, but tree species varied in their propensity to form cavities. Beech (Fagus grandifolia; 0.41 cavities/tree) and sycamore (Plantanus occidentalis; 0.50 cavities/tree) were prolific cavity producers, whereas a small proportion (0.05 cavities/tree) of cottonwoods (Populus deltoides) contained cavities. Kaplan–Meier estimates of annual and 10-year cavity persistence averaged 0.95 and 0.64, respectively. Cavity persistence also differed among species (P = 0.02): cottonwoods had the lowest (0.54) and sycamores had the highest (0.89) 10-year tree cavity persistence rates. Tree fall (50.0%), cavity floor deterioration (37.5%), and narrowing of the cavity entrance (12.5%) were the most prevalent causes of tree cavity loss. Forest stand projections indicated that cavity abundance will increase up to 34% over recent levels during the first 10 years and by 44% after 50 years. Most of this increase will be contributed by tree species that are not commonly used by wood ducks, but cavities will increase in oaks (Quercus spp.) and beeches as the forest matures into cavity-bearing size classes. Sycamores will steadily contribute cavities, but cottonwood is predicted to provide fewer cavities due to low survival of cavity-bearing size classes. Our results suggest that availability of nest and den sites for cavity-dependent wildlife will increase as eastern deciduous forests mature over the next half century. Cost-effectiveness of artificial nest box programs should be reevaluated in light of projected changes in tree cavity availability as deciduous forests mature in the eastern United States.

Because of significant declines in mule deer (Odocoileus hemionus) populations across New Mexico, USA, we investigated survival of fawns in north-central New Mexico, USA. We captured 19 fawns, 34 fawns, and 47 fawns in 2002, 2003, and 2004, respectively, and used fawn morphological measurements, habitat characteristics, and adult female (hereafter “female”) condition to model preweaning fawn survival. Survival was 0.0, 0.12, 0.52 for 2002, 2003, and 2004, respectively, and was related to birth mass (χ₁² = 9.5, P = 0.002), birth date (χ₁² = 8.4, P = 0.004), litter size (χ₂² = 9.4, P = 0.009), female body fat (χ₁² = 40.9, P < 0.001), annual precipitation (χ₁² = 35.0, P < 0.001), summer precipitation (χ₁² = 37.5, P < 0.001), and winter precipitation (χ₁² = 32.0, P < 0.001). Total ingesta-free body fat of females (β = 3.01, SE = 0.75; odds ratio = 20.19, 95% CI = 4.64–87.91) and birth mass of fawns (β = 1.188, SE = 0.428; odds ratio = 3.38, 95% CI = 1.42–7.59) were the best predictors of survival of individual fawns, although few of the logistic models differed in model selection criteria. Fawn survival in north-central New Mexico was driven by an interaction of total and seasonal precipitation and its effect on plant production, consequential effects on female nutrition, and ultimately, fawn birth attributes. Habitat conditions were so poor throughout north-central New Mexico during 2002 and 2003 (and likely during other drought yr) that, based upon birth attributes, few fawns could have survived regardless of proximate causes of mortality. In 2004, precipitation enhanced security cover, maternal body condition, birth attributes and, thus, survival of fawns. However, more habitat enhancements are needed to improve the nutritional quality of mule deer habitats in north-central New Mexico and further enhance maternal and fawn condition to recover mule deer populations in this region.

Age-specific reproduction has been suggested for northern bobwhite (Colinus virginianus) and has been hypothesized as a factor contributing to population irruptions. However, little research has been conducted on the subject. We conducted a laboratory and field study to determine if age-specific reproduction occurred in northern bobwhites. Our objectives were to compare 7 reproductive measures (% F nesting, date of first incubated nest, egg-laying rate, nesting rate, clutch size, egg mass, and egg hatchability) between first- and second-year breeders and determine if differential reproduction was impacted by diet quality. The laboratory study consisted of a 2 × 2 factorial experiment with age and diet quality (low protein [12%] and high protein [24%]) as the factors. Data for the field study represented a 6-year data set of bobwhite reproduction (May–Sep 2000–2005) obtained from an ongoing radiotelemetry study in southern Texas, USA. We documented similar productivity (i.e., % F laying, egg-laying rate, and egg mass) and timing of laying (i.e., date of first egg) between juvenile (n = 33) and adult bobwhites (n = 27) in our laboratory study. However, females on the high-protein diet exhibited a greater egg-laying rate than females on the low-protein diet. Under field conditions, we also documented no difference in productivity (% F nesting, nesting rate, clutch size, egg hatchability) and timing of nesting (date of first incubated nest) between age classes (n = 59 juv and 32 ad). Our findings do not support early suppositions of age-specific reproduction in quail. Quail irruptions should not be influenced by population age structure as it relates to age-specific reproduction.

Grazing is thought to be incompatible with nesting by dabbling ducks (Anas spp.), but this belief is based on little data. We therefore conducted a 2-year, replicated field experiment to determine whether the habitat requirements of nesting ducks could be met on uplands managed by rotational grazing (1 Jul–1 Nov) in the northern San Joaquin Valley, California, USA. Grazed fields had shorter vegetation than ungrazed fields throughout the winter, but vegetation height did not differ by the beginning of the nesting season in late March, and by the end of the nesting season in late May, previously grazed fields had taller vegetation than did ungrazed fields. In 1996, densities of duck nests were >3 times higher in grazed than in ungrazed fields (least-squares means [± 1 SE]: grazed = 2.18 [0.34] nests/ha, ungrazed = 0.59 [0.34] nests/ha), but nest densities were substantially lower in 1997 and did not differ between treatment groups (grazed = 0.65 [0.32] nests/ha, ungrazed = 0.39 [0.32] nests/ha). Mayfield nest success did not differ between grazed fields (5.3%) and ungrazed fields (2.9%). We conclude that rotational grazing was successful in providing summer nesting habitat for dabbling ducks, and we recommend that it be considered for other managed habitats within the Central Valley, California, USA.

Ungulate populations in desert environments are thought to be regulated by precipitation. Pronghorn (Antilocapra americana) populations in Trans-Pecos, Texas, USA, experienced a 70% decline between 1977 and 2001. The causative factors associated with the decline are unknown but appear to be related to drought. We evaluated the relationships between pronghorn abundance and productivity and precipitation (i.e., raw precipitation, Palmer Drought indices) for the Trans-Pecos district of Texas from 1977 to 2004. Pronghorn productivity (range = 305–4,407) and abundance (range = 5,061–17,266) showed high variability. Precipitation was also highly variable, ranging from 18 cm to 57 cm. Pronghorn abundance was positively influenced by precipitation indices (R = 0.790, P < 0.001). The relationship between fawn production and raw precipitation (R = 0.869, P < 0.001) suggested that fawn production may be more closely related to immediate moisture conditions, whereas pronghorn abundance was more influenced by long-term population trends. Management plans for pronghorn populations in more arid regions should include drought contingencies including reduced stocking rates and harvest quotas.

We assessed winter forage selection by white-tailed deer (Odocoileus virginianus) on Anticosti Island, Quebec, Canada, using cafeteria-feeding trials. Winter habitat on Anticosti is degraded and free-ranging deer at high densities consume 70% balsam fir (Abies balsamea) and 20% white spruce (Picea glauca), even though spruce is much more available than fir. Deer ate 89.9% balsam fir and 10.1% white spruce when the availability of both trees was equal. Deer did not eat shredded twigs more than intact twigs. Fiber content and condensed tannins were greater in white spruce than in balsam fir. Deer preference for fir was not based on texture but, more likely, on plant constituents, so we concluded that deer will nearly eliminate fir before they use any significant amount of white spruce. Management actions, therefore, need to be undertaken to enhance balsam fir regeneration.

Free-roaming cats (e.g., owned, semi-feral, and feral) impact wildlife worldwide through predation, competition, and disease transmission. Baseline ecological information necessary for population management is lacking. We radiocollared free-roaming cats (feral, n = 30; semi-feral, n = 14; owned, n = 10) in Caldwell, Texas, USA between October 2004 and November 2005 and compared population demographics among sex and ownership classification. We found ranges and movements declined across ownership classes whereas survival and fecundity increased. Our findings suggest that human interactions (e.g., feeding) may result in high, localized free-roaming cat densities, which may concentrate feral cat impacts and should be considered when evaluating population control strategies.

I present marrow fat (MF) data from a large sample of white-tailed deer fawns killed by wolves and a sample of fawns that died by accident in a single area, and I use these data to explore the extent that poor nutritional condition may have predisposed fawns to wolf predation. Percent MF of 110 5–10-month-old white-tailed deer (Odocoileus virginianus) fawns killed by wolves (Canis lupus) from November through April 1984–2002 in northeastern Minnesota, USA, was lower than MF for 23 fawns killed by accidents in the same area and period. The MF of both male and female wolf-killed fawns decreased over winter. The MF of male fawns decreased as a snow-depth index increased, but MF of females showed little relationship to the snow-depth index and was higher than that of males. Poor nutritional condition is one factor that predisposes deer fawns to wolf predation during winter and spring. This information expands our knowledge of wolf–prey relations by documenting that, even with younger prey animals that might be thought vulnerable because of youth alone, poor nutritional condition also is an important factor predisposing them to wolf predation.

Regional wildlife–habitat models are commonly developed but rarely tested with truly independent data. We tested a published habitat model for black bears (Ursus americanus) with new data collected in a different site in the same ecological region (i.e., Ouachita Mountains of Arkansas and Oklahoma, USA). We used a Mahalanobis distance model developed from relocations of black bears in Arkansas to produce a map layer of Mahalanobis distances on a study area in neighboring Oklahoma. We tested this modeled map layer with relocations of black bears on the Oklahoma area. The distributions of relocations of female black bears were consistent with model predictions. We conclude that this modeling approach can be used to predict regional suitability for a species of interest.

Although numerous studies have documented behavioral effects of nature-based tourism on wildlife populations, few studies have determined whether behavioral changes translate to effects on individual condition and population health. This issue is currently a concern for wildlife managers in Alaska, USA, and Canada where bear viewing is a rapidly growing industry expanding into previously undisturbed bear habitats. Rather than record observations at long established tourism sites, we experimentally introduced bear viewing into 2 relatively undisturbed brown bear (Ursus arctos) populations in south-central Alaska. We examined the nutritional consequences of behavioral changes induced by the presence and activity of bear viewers for bears feeding on early summer vegetation and late-summer salmon (Oncorhynchus kisutch and O. nerka). We used Global Positioning System collars, monitored food resource availability, and quantified individual resource use and condition for a year prior to and during the introduction of bear viewing. Though bear viewing altered spatiotemporal resource use in all treatments, total resource use declined only when we exposed bears to 24-hour daily human activity. Energy expenditure, indexed as daily travel distances, was significantly higher when bears responded by altering spatial rather than temporal resource use. However, body weight and composition were unaffected by all treatments as bears shifted their foraging to other locations or times. Managers can minimize nutritional impacts of bear-viewing programs by avoiding spatial displacement and providing predictable time periods when bears can access food resources free of human activity. Bears in this study exhibited a high degree of behavioral plasticity, which may be an important factor in identifying flagship species for sustainable ecotourism programs.

As humans continue to move further from the urban epicenter and expand into suburban and exurban areas, problems involving coexistence of wildlife and human populations will become increasingly common. Wildlife biologists will be tasked with reducing wildlife–human conflicts, and their effectiveness will be a function of their understanding of the biology and life-history characteristics of wildlife populations residing in areas with high human density. In this study, we examined causes and timing of deaths of neonatal white-tailed deer (Odocoileus virginianus) in an exurban area of Alabama in 2004 and 2005, estimated survival rates, and determined factors that influenced survival for the initial 8 weeks of life. We found 67% mortality, with the leading causes being predation by coyotes (Canis latrans; 41.7%) and starvation due to abandonment (25%). These results suggest that coyote predation may be a significant source of natural mortality in exurban areas. Contrary to our original expectations, vehicle collisions were not an important cause of mortality.

Estimating survival of the offspring of marked female ungulates has proven difficult in free-ranging populations yet could improve our understanding of factors that limit populations. We evaluated the feasibility and efficiency of capturing large samples (i.e., >80/yr) of neonate mule deer (Odocoileus hemionus) exclusively from free-ranging, marked adult females using vaginal implant transmitters (VITs, n = 154) and repeated locations of radiocollared females without VITs. We also evaluated the effectiveness of VITs, when used in conjunction with in utero fetal counts, for obtaining direct estimates of fetal survival. During 2003 and 2004, after we placed VIT batteries on a 12-hour duty cycle to lower electronic failure rates, the proportion that shed ≤3 days prepartum or during parturition was 0.623 (SE = 0.0456), and the proportion of VITs shed only during parturition was 0.447 (SE = 0.0468). Our neonate capture success rate was 0.880 (SE = 0.0359) from females with VITs shed ≤3 days prepartum or during parturition and 0.307 (SE = 0.0235) from radiocollared females without VITs or whose implant failed to function properly. Using a combination of techniques, we captured 275 neonates and found 21 stillborns during 2002−2004. We accounted for all fetuses at birth (i.e., live or stillborn) from 78 of the 147 females (0.531, SE = 0.0413) having winter fetal counts, and this rate was heavily dependent on VIT retention success. Deer that shed VITs prepartum were larger than deer that retained VITs to parturition, indicating a need to develop variable-sized VITs that may be fitted individually to deer in the field. We demonstrated that direct estimates of fetal and neonatal survival may be obtained from previously marked female mule deer in free-ranging populations, thus expanding opportunities for conducting field experiments. Survival estimates using VITs lacked bias that is typically associated with other neonate capture techniques. However, current vaginal implant failure rates and overall expense limit broad applicability of the technique.

If individuals can be identified from patterns in their footprints, noninvasive survey methods can be used to estimate abundance. Track plates capture fine detail in the footprints of fishers (Martes pennanti), recording rows of dots corresponding to tiny papillae on the animal's metacarpal pad. We show that the pattern of these dots can be used to identify individual fishers, similar to human fingerprints. A probabilistic model of uniqueness based on variation in spacing between 1,400 pairs of dots that we measured in prints of 14 different fisher feet suggests the probability of encountering a similar pattern in the print of a different foot by chance alone is <0.35ⁿ, where n = the number of dot pairs examined. This predicts a 0.00003 probability that a match made using 10 pairs of dots is false. Dot spacing from footprints made by the same foot was remarkably consistent (σ = 0.02 mm, n = 24 dot pairs). Combined, these results suggest dot patterns in fisher footprints were unique to individuals and were consistently reproduced on track plates. Empirical tests of matching accuracy were best with good-quality prints, highlighting the need for experience judging when prints are usable. We applied print matching to fisher detections collected on track plates deployed at 500-m intervals along 10 3.5-km transects in the Adirondack region of New York, USA. Of 62 fisher detections, 85% had ≥1 footprint of suitable quality to compare with other high-quality prints. We found that most detections from a transect were from the same individual fisher suggesting nonindependence of detections. Thus, data from traditional track-plate deployments over small time periods cannot be used as a measure of abundance, but new study designs using print matching could obtain robust noninvasive, mark–recapture density estimates.

Although fecal pellet counts have been widely used to index changes in deer abundance in forests, few studies have modeled the relationship between the indices and deer density. We examined the relationships between 3 fecal pellet indices (total pellets, pellet groups, and pellet frequency) and the density of deer (primarily red deer [Cervus elaphus scoticus]) in 20 enclosures in the North and South islands of New Zealand. In each enclosure we estimated the 3 indices on 30 randomly located 150-m transects, with each transect having 30 circular plots of 3.14 m². We developed 4 candidate models (1 linear and 3 nonlinear) to describe the relationship between the indices and deer density. We used a Bayesian analysis to account for uncertainty in the estimates of deer abundance and to facilitate fitting models that included random transect effects. The 4 models explained the relationship between the 3 indices and deer density similarly well. The slopes of the linear relationships between the 3 indices and deer density were positive. Our results suggest that fecal pellet counts may be useful indices of deer abundance.

Two challenges in wildlife telemetry are optimizing the duration of transmitter attachment and minimizing the impacts of radios on the behavior and demography of the study animal. We tested 4 methods of radio attachment for a breeding population of upland sandpipers (Bartramia longicauda) under natural conditions at a tallgrass prairie site in Kansas, USA. To estimate radio retention and weekly survival rates, we used the nest survival model of Program MARK. Radio retention was lowest at the start and the end of the breeding period. The expected duration of radio retention was 1.8 years for a leg-loop harness, 40 days for radios glued to clipped feathers, 26 days for radios glued directly to feathers, and 7 days for radios glued to bare skin. Few radiomarked birds died during our study, but 4 of 8 mortality events were discovered within one week of radiomarking. Both glue and harnesses increased predation risk immediately after radio attachment. The weekly probability of survival was high after a 1-week acclimation period, and the expected survival for a 10-week breeding period was similar in males and females. Attachment of radios with glue had no effect on annual return rates. However, attachment of radios with leg harnesses resulted in lower return rates among radiomarked birds than birds without radios. Radios attached with glue were shed in <1 year but radios attached with harnesses were retained for up to 1–2 years. Our results indicate a tradeoff between optimizing radio retention and minimizing impacts on demography. Glue techniques had retention rates that were suitable for only short-term studies, but attachment with glue had no long-term effect on annual return rates. Leg harnesses provided effective radio retention that had little effect on survival rates during the stationary breeding period, but resulted in lower annual return rates. Robust estimates of radio retention and survival will assist researchers in selecting attachment techniques that best meet the study goals of future telemetry projects.

Survey techniques that are both reliable and efficient are necessary to accurately estimate population parameters, especially for rare species. Cactus ferruginous pygmy-owls (Glaucidium brasilianum cactorum; hereafter pygmy-owls) have declined in southwestern North America and are surveyed often to comply with federal law. We studied owl responses to broadcasted calls to quantify how detectability and response rates (owls/station/transect) vary with environmental, spatial, temporal, and weather-related factors. We surveyed owls along 392 transects (1,113 km) throughout Sonora, Mexico, including a subset of 14 transects (47.2 km) that we surveyed repeatedly to assess factors that affected response rates. We challenged 17 adults and 23 juveniles that were radiomarked, adults attending 50 occupied nests, and adults attending 6 groups of radiomarked juveniles to respond to broadcasted calls to assess factors that affected detectability. Across Sonora, response time averaged 2.6 ± 0.1 minutes (𝑥̄ ± SE, n = 520), with 99 ± 0.4% of owls detected in ≤8 minutes; response distance averaged 251 ± 7 m, with 91 ± 1% of owls detected at ≤400 m. Response time decreased by an average of 4 ± 2% and response distance decreased by 12 ± 3 m with each half-month period from early courtship through brooding (P ≤ 0.035). Response time averaged 39 ± 24% faster during morning than midday at occupied nests. Detectability was 1.0 ± 0.0 when surveyors were 100 m from occupied nests and decreased to 0.78 ± 0.10 when surveyors were 500 m from occupied nests. Detectability was higher during incubation, brooding, and natal dispersal (0.89 ± 0.05–1.0 ± 0.0) than during fledgling-dependency (0.50 ± 0.20–0.67 ± 0.19). Response rates of males did not vary from early courtship to brooding (P = 0.84), yet those of females decreased systematically to zero across the same period (P < 0.001). Because detectability of pygmy-owls remains consistently high during nesting, response rates generated from carefully designed surveys can provide reliable estimates of occupancy and abundance.

Standardized, effective sampling methods are required to monitor amphibian population trends and community composition. Funnel traps have been used to ostensibly estimate species richness and relative abundance of larval amphibians. We tested whether funnel traps can be used to provide unbiased estimates of amphibian community composition in playa wetlands by comparing seining–dip netting and passive funnel-trapping results. Plains spadefoots (Spea bombifrons) were more prone to be captured in funnel traps whereas New Mexico spadefoots (S. multiplicata) were less likely captured by funnel traps than by seines and dip nets. In playas funnel traps should be used only for collecting specimens and not for estimating amphibian community composition.

Home-range models implicitly assume equal observation rates across the study area. Because this assumption is frequently violated, we describe methods for correcting home-range models for observation bias. We suggest corrections for 3 general types of home-range models including those for which parameters are estimated using least-squares theory, models utilizing maximum likelihood for parameter estimation, and models based on kernel smoothing techniques. When applied to mule deer (Odocoileus hemionus) location data, we found that uncorrected estimates of the utilization distribution were biased low by as much as 18.4% and biased high by 19.2% when compared to corrected estimates. Because the magnitude of bias is related to several factors, future research should determine the relative influence of each of these factors on home-range bias.

Satellite tracking is currently used to make inferences to avian populations. Cost of transmitters and logistical challenges of working with some species can limit sample size and strength of inferences. Therefore, careful study design including consideration of sample size is important. We used simulations to examine how sample size, population size, and population variance affected probability of making reliable inferences from a sample and the precision of estimates of population parameters. For populations of >100 individuals, a sample >20 birds was needed to make reliable inferences about questions with simple outcomes (i.e., 2 possible outcomes). Sample size demands increased rapidly for more complex problems. For example, in a problem with 3 outcomes, a sample of >75 individuals will be needed for proper inference to the population. Combining data from satellite telemetry studies with data from surveys or other types of sampling may improve inference strength.

Here we provide the first assessment of the accuracy of lightweight satellite transmitters (<80 g) under actual operating conditions and the performance of the Argos system in southern Europe. To estimate transmitter accuracy we used transmitters equipped with a Global Positioning System (GPS) and compared the location estimates provided by Argos with the estimates provided by the GPS. Using the 68th percentile to define the accuracy of locations estimates, observed accuracy was 4 km for Location Class (LC) 1, 15 km for LC 0, 20 km for LC A, and 59 km for LC B, which is in line with estimates reported by other authors. Yet, the error of the remaining 32% of the data ranged between 4 km and 11 km, 15 km and 217 km, 20 km and 145 km, and 59 km and 493 km, respectively, suggesting that using the 68th percentile to estimate accuracies might give misleading confidence on the accuracy of location estimates. Using the 90th percentile is probably more appropriate. Less than 10% of the locations we obtained corresponded to the more accurate LCs (3, 2, and 1), with Argos failing to provide a position estimate in 45% of the attempts. The low number of high-quality location estimates is likely a consequence of the electromagnetic interference reported for our study area, rather than a defect of the Platform Transmitter Terminals (PTTs), which under good conditions of signal reception seem to be as reliable as heavier ones. The recent advent of lightweight GPS transmitters overrides most of these problems. Yet, whereas the smallest Argos-GPS PTTs weigh 30 g, which restricts their use to animals weighting >1,000 g, conventional PTTs can be as small as 9.5 g, allowing their use with animals weighting 250–300 g.

Degradation of sagebrush habitat and a lack of information on current status motivated a petition to list the pygmy rabbit (Brachylagus idahoensis) as threatened or endangered under the Endangered Species Act. The petition brought on renewed interest in obtaining data on pygmy rabbits; however, pygmy rabbits are notoriously difficult to capture, especially in summer. We tested box-trap, net, noose-pole, and fabric-fence methods to capture pygmy rabbits in 4 areas of northern Nevada and eastern California, USA. We captured 25 different pygmy rabbits in 30 captures from April 2005 to July 2006. The combination of camouflaged box traps baited with canned green beans was 35% more successful and required less effort per captured rabbit than any other method. Noose-pole methods also were successful. These techniques provide an efficient method of capturing pygmy rabbits in summer when many remote field sites are most accessible.