Recent concern over global amphibian population declines has highlighted a need for more extensive, rigorous monitoring programs. Two sources of variation, spatial variation and variation in detection probability, make the design and implementation of effective monitoring programs difficult. We used Pollock's robust design in a 3-year capture–recapture study to estimate detection probability and temporary emigration for Plethodon salamanders in Great Smoky Mountains National Park (Tennessee/North Carolina), USA. We used 12 competing models to determine the importance of temporary emigration, and we explored temporal and behavioral effects on conditional capture probabilities. The top 4 models all included random temporary emigration, and Akaike model weights indicated that this parameter was the most important. Models that contained behavioral effects in capture probabilities were selected more often than models with equal capture probabilities for marked and previously unmarked individuals. The “best” model contained random emigration and behavioral effects and was selected 4 times as often as any other model. When we included Markovian emigration, the probability of emigrating from the surface usually was less than the probability of remaining an emigrant (73% of site-years). Markovian emigration estimates often were similar and always had overlapping confidence intervals, thus the Markovian model rarely was chosen over the random emigration models (only 9.6% of site-years). Our study is the first to formally estimate temporary emigration in terrestrial salamander populations, and our results verify that significant proportions of terrestrial salamander populations are subterranean. We determined that the probability of capturing salamanders on the surface may also vary temporally within a sampling season. Therefore, we caution against using unadjusted count indices to compare salamander populations over time or space unless detection probabilities are estimated. Temporary emigration models will improve abundance estimates when a large proportion of the population is unavailable for capture during a given sampling period.

Recent worldwide amphibian declines have highlighted a need for long-term, large-scale monitoring programs. Scientific or management objectives, appropriate spatial sampling, and detectability all must be considered when designing monitoring programs (Yoccoz et al. 2001). The ability to establish meaningful monitoring programs currently is compromised by a lack of information about amphibian detection probabilities. We used Pollock's robust design and capture–recapture models that included temporary emigration to test a priori hypotheses about spatial and temporal variation in salamander detection probability parameters for populations found in Great Smoky Mountains National Park (Tennessee/North Carolina), USA. We explored the effects of 3 large-scale habitat characteristics (disturbance history, elevation, vegetation type) and found that vegetation type and elevation were correlated with detection probabilities. Vegetation type was an important covariant in estimates of temporary emigration, conditional capture probability, and surface population size. Contrasts that isolated elevation effects were significant for all detection probability parameters except recapture probability, despite our small elevational range (330 m). When detection probability parameters have the potential to vary over time and space, investigators should develop monitoring designs that permit the estimation of detection probabilities.

We used the Cormack-Jolly-Seber model to estimate the effects of radiotransmitters on survival of breeding northern goshawks (Accipiter gentilis). We separately compared apparent annual survival of leg-banded goshawks with (1) tailmount- and (2) backpack-style radiotransmitters (hereafter tailmounts and backpacks) to apparent annual survival of breeding adults with legbands only. The best model without radiotransmitter effects, evaluated with Akaike's Information Criterion (AIC_c), suggested no gender- or year-specific effects on survival. We then added radiotransmitter attachment type (tailmount or backpack) and mass of radiotransmitter as covariates to the base model to estimate the effect of radiotransmitters. Tailmounts on males significantly reduced apparent annual survival from 0.75 (SE = 0.02, 95% CI: 0.71 to 0.78) without radiotransmitters to 0.29 (SE = 0.15, 95% CI: 0.09 to 0.63) with radiotransmitters. Backpacks had no significant effect on survival of adults (0.79, SE = 0.17, 95% CI: 0.33 to 0.97). The strikingly lower survival of goshawks with tailmounts was surprising because tailmounts weighed less (10 g, 1.5% body mass) than backpacks (16–23 g, max = 3.4% body mass) and likely were carried for shorter periods. Due to the small number of goshawks with tailmounts (n = 14) in this study, our results possibly were due to chance. We therefore recommend additional study of the effects of tailmounts on survival of breeding male northern goshawks.

To assess spotted owl use of young forests, we studied home-range sizes and habitat-use patterns of 24 adult northern spotted owls (Strix occidentalis caurina) on 2 sites in the Oregon Coast Range: the Elliott State Forest (ESF) and state forest lands in the Northern Coast Range (NCR). Conifer forests at ESF were characterized by a mixture of old, mature, and pole-sized conifer, similar to other areas occupied by spotted owls in western Oregon, USA. In contrast, conifer forests at NCR were younger than most other sites occupied by spotted owls in western Oregon and consisted primarily of conifers <80 years old. Broadleaf forest also was abundant (approx 22%) at both ESF and NCR. We used an information–theoretic approach and Akaike's Information Criterion (AIC) to evaluate a priori hypotheses about spotted owl home-range sizes and habitat-use patterns on our study areas. Considering previous knowledge about habitat requirements of the species, we predicted that owls occupying sites with fewer old conifer stands would have larger home ranges and that owls would select the oldest and most structurally diverse forest available for foraging and roosting. Our top model for evaluating home-range sizes indicated that the proportion of older conifer forest within the home range best explained the variability in home-range sizes. Although we found considerable variation in home-range size among owls, home-range sizes at ESF generally were smaller than home-range sizes at NCR, and home ranges at both sites were smaller than those reported for other study areas in western Oregon. Habitat-use patterns also varied widely among owls both within and between sites. Models containing distance to the nest tree, proximity to nearest forest edge, and proximity to nearest broadleaf-forest edge were the most parsimonious models for distinguishing owl locations from random points. On average, owl locations at both study areas were closer to ecotones between broadleaf forest and other cover types and farther from forest–nonforest ecotones than random points. Overall, we did not observe strong selection or avoidance of any cover type, although owls at ESF showed greatest use of older conifer forest while owls at NCR showed greatest use of broadleaf forest. Use of these habitat configurations and cover types by spotted owls had not been well documented prior to our study. The predictive power of our models was not great, however, indicating that factors in addition to those we included in our analysis may have influenced owl habitat-use patterns at our study areas. Based on our results, we recommend that managers at these sites maintain existing old and mature conifer forest, broadleaf forest, broadleaf-forest edges, and forested riparian areas as owl habitat; avoid timber harvest in core use areas; and plan the size of areas managed for spotted owls to reflect actual home-range and core-area sizes for owls in those forests.

We used point counts to sample bird communities in hardwood forest stands following single-tree selection harvest to determine the impacts on birds of this harvesting system. We sampled at 1–5 years post-harvest (n = 24), 15–20 years post-harvest (n = 23), and in reference stands subjected only to natural disturbances for >30 years (n = 24). White-throated sparrow (Zonotrichia albicollis), chestnut-sided warbler (Dendroica pensylvanica), and mourning warbler (Oporornis philadelphia) abundances were significantly higher in recently logged stands than in other treatments. Ovenbird (Seiurus aurocapillus) abundance was about 50% lower in recently logged stands and in stands logged 15–20 years previous than in reference stands. Black-throated blue warbler (Dendroica caerulescens) and yellow-bellied sapsucker (Sphyrapicus varius) abundances were similar in reference and recently logged stands but significantly lower in stands harvested 15–20 years previously. Redundancy Analysis (RDA) identified 6 habitat variables associated with changes in avian abundances. Percent shrub and slash cover were higher in recently logged stands than in older logged and reference stands. Deciduous canopy cover and basal area of living deciduous trees were greater in reference stands than in both logged treatments. Although the abundance of some bird species were statistically lower in selection cut stands, the implications to population persistence will require data on reproductive success in combination with population modeling with varying proportions of the forested landscape committed to selection cutting.

We examined winter habitat preferences of individual dunlin (Calidris alpina) in the Fraser River delta, British Columbia, Canada, adjacent to agricultural land near an area of dense and increasing human settlement. We used radiotelemetry and compositional analysis to quantify and describe dunlin habitat selection at 2 scales (regional and local) throughout the 24-hr day and daily tidal cycles. We tested for differences between sex and age classes, and among birds captured at different sites. Patterns of habitat preference differed between sexes and among dunlin from different sites in the delta, but we detected no difference between age classes. We ranked habitat types in order of dunlin preference and tested for significant differences among habitat ranks. Dunlin showed a significant preference for tidally influenced marine habitats at both scales and throughout the study area. However, most individuals (>80%) also used terrestrial habitats, usually during high tide and primarily at night. The role of terrestrial habitats in the ecology of Fraser River delta dunlin previously had been underestimated because these habitats are used far more at night than during the day. Regionally, soil-based agricultural crops ranked above other terrestrial habitats, and pasture was the only terrestrial habitat that was ranked highly and preferred at both scales. Pasture vegetation tends to be short, and pasture fields in the Fraser River delta are fertilized heavily and naturally with cattle manure. We recommend that managers promote the maintenance of a mosaic of soil-based agricultural crops—with a particular emphasis on naturally fertilized pastures—for dunlin and other shorebirds wintering in the Fraser delta. Terrestrial habitat fragmentation also should be kept to a minimum, as dunlin preferred large fields, likely in response to predation risk.

Ricefields are important foraging habitats for waterfowl and other waterbirds in primary North American wintering regions. We conducted a large-scale experiment to test effects of post-harvest ricefield treatment, winter water management, and temporal factors on availabilities of rice, moist-soil plant seeds, aquatic invertebrates, and green forage in the Mississippi Alluvial Valley (MAV), Mississippi, USA, fall–winter 1995–1997. Our results revealed that a large decrease in rice grain occurred between harvest and early winter (79–99%), which, if generally true throughout the MAV, would have critical implications on foraging carrying capacity of ricefields for migrating and wintering waterbirds. During the remainder of winter, food resources generally were similar among treatment combinations. An exception was biomass of aquatic invertebrates, which demonstrated potential to increase by late winter in ricefields that remained flooded. We offer revised calculations of foraging carrying capacity for waterfowl in MAV ricefields and recommend continuing research and management designed to increase availability of residual rice and aquatic invertebrates in winter.

Female wood ducks (Aix sponsa) feed primarily on plant foods in the prelaying period and switch to a diet of mostly invertebrates during egg production. If nutrient acquisition is habitat-specific, then selection and use of habitats may differ between these reproductive stages. A better understanding of these processes is needed to assist future habitat conservation and management efforts. In January–May 1999 and 2000, we monitored movements and habitat use of radiomarked females (n = 47) during the prelaying and egg-production periods of first nests. Home-range size averaged 367 ha and did not vary with reproductive period, year, or female age. Habitat use did not differ between periods of prelaying and egg production; consequently, data were combined. Habitat use varied between years, female age, and periods of nest initiation (i.e., early vs. late). Use of beaver ponds (BP), temporary wetlands (TW), managed impoundments (MI), and lake habitats (LK) declined in 2000 compared to 1999, possibly due to reduced precipitation. Nest initiation date was independent of female age. Adult females used BP more than yearlings, and early-nesting females used BP and MI more than late-nesting females. Females selected habitats nonrandomly when habitat composition of the study area was compared to that of home ranges (second-order selection). Lake-influenced wetlands (LI) and MI were ranked highest in preference. Home-range size was inversely related to percentage of the home range comprised of MI and LI, supporting the idea that MI and LI were high-quality habitats. However, we found no relationship between nest initiation date (an important index to reproductive performance) and the combined area of MI and LI in home ranges. Habitat selection did not differ from random when habitat composition of home ranges was compared to that of radio locations (third-order selection). Although MI and LI were preferred, high-quality habitats, our results suggest that breeding female wood ducks can satisfy requirements for egg production using a variety of wetland habitats. We suggest that providing a diversity of habitat types will increase the probability of meeting needs of breeding females throughout the breeding season, especially in areas where wetland conditions frequently change.

We examined how harvest affected natural mortality rates and how the dynamics of northern bobwhite (Colinus virginianus, hereafter bobwhite) covey membership might affect the additive nature of harvest. We conducted repeated searches for coveys and radiomarked all coveys found on 12 259-ha study areas in east-central Kansas, USA. We simulated a harvest in 6 randomly selected areas each year during November–January, 1997–2000, by trapping and removing 60% of bobwhites in each covey. We used flush counts and radiotelemetry to measure harvest effects on natural mortality rates, overall winter survival, covey size, and densities. Observed natural mortality rates of radiomarked individuals were similar between harvested (50.6 ± 4.3%) and unharvested areas (52.1 ± 4.7%). Estimated winter survival was 47.9% on the unharvested areas and 20.9% on the harvested areas. Harvest did not affect the number of coveys, average covey size, or density of bobwhites, indicating that coveys coalesced through local movement. Our results indicate that harvest is additive to natural mortality and suggest that local movement to maintain optimal group sizes can mask the true effect of harvest on observed densities in small areas.

We studied reindeer (Rangifer tarandus tarandus) distribution in relation to possible travel barriers (roads and power lines) in south-central Norway, 1997–2000, using lichen biomass as an indicator of reindeer use. We recorded lichen cover on both sides of potential barriers within comparable habitat in 42 sites for 3 different reindeer herds. We used cover–biomass regressions to assess the relationship between lichen cover and biomass. In 2 of the regions, lichen biomass was 5.3 times and 2.8 times higher in areas isolated by 2 parallel power lines and an adjacent winter-closed road compared to biomass on the other side of the potential barrier. In a third region, lichen biomass did not vary significantly between areas on either side of a single winter-closed road. Lichen biomass data suggested that wild reindeer used both sides of a closed road in winter, whereas 2 parallel power lines and a winter-closed road in combination reduced reindeer migration and resulted in very different grazing pressures on either side of the power lines, even 30 years after the power lines were constructed. Construction of power lines, and particularly parallel power lines, should thus be avoided in wild reindeer habitat. Fragmentation of wild reindeer ranges in Norway results in a substantial reduction in available ranges and traditional migration routes between important seasonal ranges, with a likely overall reduction in carrying capacity.

California's 22 tule elk (Cervus elaphus nannodes) herds reportedly were founded by the single elk pair remaining in southern California in the 1870s and have been extensively managed during the ensuing 132 years. In our study, the first report of microsatellite variation among tule elk herds, we detected few significant genetic differences among herds. Furthermore, variation at 12 microsatellite loci was extremely limited within tule elk herds. We found large, significant differences between tule elk and both Rocky Mountain (C. e. nelsoni) and Manitoban elk (C. e. manitobensis) at the same 12 microsatellite loci. Tule elk possessed ≤50% of the allelic diversity and heterozygosity found in the other subspecies. Tule elk were fixed at 5 loci at which the other subspecies possessed an average of 4.6 alleles. We observed very large pairwise F_st values and genetic distances between tule elk and both other subspecies, likely due to the very restricted variation in tule elk, rather than the presence of unique variation. Modeling of the genetic characteristics of tule elk indicated that management strategies involving transplants among all tule elk herds appear to be the most beneficial for the maintenance of nuclear variation in this subspecies. We also investigated impacts of small herd size and varying sex ratios on maintenance of microsatellite variation in tule elk.

We used cohort analysis to reconstruct a Columbian black-tailed deer (Odocoileus hemionus columbianus) population from 1979 to 1999 in the western Cascade Range, Washington, USA. We used reconstructed population estimates and age-class representations to analyze relationships among fawn recruitment, deer density, forage availability, and weather influences during the fawning period. Fawn recruitment was found to be significantly correlated with deer density the previous year as well as available forage in the previous year. Weather variables that described cold temperatures early in the fawning period and high precipitation levels during the prime fawning period were found to negatively affect fawn recruitment. Models could be used to assist with management of black-tailed deer by providing an estimate of cohort strength when productivity survey methods prove difficult.

The tradition of early elk (Cervus elaphus) hunting seasons adjacent to Yellowstone National Park (YNP), USA, provides grizzly bears (Ursus arctos horribilis) with ungulate remains left by hunters. We investigated the fall (Aug–Oct) distribution of grizzly bears relative to the boundaries of YNP and the opening of September elk hunting seasons. Based on results from exact tests of conditional independence, we estimated the odds of radiomarked bears being outside YNP during the elk hunt versus before the hunt. Along the northern boundary, bears were 2.40 times more likely to be outside YNP during the hunt in good whitebark pine (Pinus albicaulis) seed-crop years and 2.72 times more likely in poor seed-crop years. The level of confidence associated with 1-sided confidence intervals with a lower endpoint of 1 was approximately 94% in good seed-crop years and 61% in poor years. Along the southern boundary of YNP, radiomarked bears were 2.32 times more likely to be outside the park during the hunt in good whitebark pine seed-crop years and 4.35 times more likely in poor seed-crop years. The level of confidence associated with 1-sided confidence intervals with a lower endpoint of 1 was approximately 93% in both cases. Increased seasonal bear densities and human presence in early hunt units increases potential for conflicts between bears and hunters. Numbers of reported hunting-related grizzly bear mortalities have increased in the Greater Yellowstone Ecosystem (GYE) during the last decade, and nearly half of this increase is due to bear deaths occurring in early hunt units during September. Human-caused grizzly bear mortality thresholds established by the U.S. Fish and Wildlife Service (USFWS) have not been exceeded in recent years. This is because agency actions have reduced other sources of human-caused mortalities, and because population parameters that mortality thresholds are based on have increased. Agencies must continue to monitor and manage hunter-caused grizzly bear mortality at sustainable levels to ensure the long-term health of the GYE population.

Understanding factors that influence and predict grizzly bear (Ursus arctos) distribution and abundance is fundamental to their conservation. In southeast British Columbia, Canada, we applied DNA hair-trap sampling (1) to evaluate relationships of grizzly bear detections with landscape variables of habitat and human activity, and (2) to model the spatial distribution and abundance of grizzly bears. During 1996–1998, we sampled grizzly bear occurrence across 5,496 km² at sites distributed according to grid cells. We compared 244 combinations of sampling sites and sessions where grizzly bears were detected (determined by nDNA analyses) to 845 site–sessions where they were not. We tested for differences in 30 terrain, vegetation, land cover, and human influence variables at 3 spatial scales. Grizzly bears more often were detected in landscapes of relatively high elevation, steep slope, rugged terrain, and low human access and linear disturbance densities. These landscapes also were comprised of more avalanche chutes, alpine tundra, barren surfaces, burned forests, and less young and logged forests. Relationships with forest productivity and some overstory species were positive at broader scales, while associations with forest overstory and productivity were negative at the finest scale. At the finest scale, the strong negative association with very young, logged forests and with increasing values of the Landsat-derived green vegetation index became positive when analyzed in a multivariate context. For multivariate analyses, we considered 2 variables together with 11 principal components that describe ecological gradients among 4 variable groupings. We applied multiple logistic regression and used AIC to rank and weight competing subset models. We derived coefficients for interpretation and prediction using multi-model inference. The resulting function was highly predictive, which we confirmed against an independent dataset. We transformed the output using a multi-annual population estimate for the sampling area, and we applied the resulting grizzly bear density and distribution model across our greater study area as a strategic-level planning tool. We discuss conservation applications and design considerations of this DNA-based approach for grizzly bears and other forest-dwelling species.

Wolf (Canis lupus) impacts on prey are a central post-wolf-reintroduction issue in the greater Yellowstone ecosystem (GYE) of the western United States. Further, estimates of wolf kill rates, used to understand these impacts, can be biased due to unrecovered kills. In Yellowstone National Park (YNP), visibility of wolves allowed us to combine independent aerial and ground observations and use a double-count method to estimate the probability of recovering kills. We consequently used these data to adjust estimates of wolf kill rates. We conducted monitoring annually from 1995 to 2000 during 2 30-day periods in early (15 Nov–14 Dec) and late winter (Mar). Estimated recovery rates of wolf kills for ground and aerial crews were 50% and 45%, respectively, although we determined that this varied by location (distance from road) and possibly age (calf or adult) of the kill. The estimated combined recovery rate was 73%. Estimated wolf kill rates were higher in late winter (2.2 kills/wolf/month) compared to early winter (1.6 kills/wolf/month), with an overall estimated rate of 1.9 kills/wolf/month. The primary prey of wolves in winter was elk (Cervus elaphus; 90%). During our study, 43% of the elk killed were calves, 28% were adult females (cows), 21% were adult males (bulls), and 9% were of unknown age/sex. Comparing prey selection to prey availability, wolf packs residing on the northern range (NR) of the GYE selected for calves, against cows, and approximately proportional to availability for bulls. Prey use was different for wolf packs occupying the NR compared to packs residing in other areas (non-northern range [NNR]) and varied seasonally for NR packs. Variation in wolf kill rates by season, and the relative stability of the northern Yellowstone elk herd during a series of mild winters despite increases in wolf density, suggest that kill rates and ultimately elk population size are influenced by winter weather. Management of ungulates should reflect the addition of wolves combined with the unpredictability of winter weather in the mountainous terrain of the western United States.

We examined prey selection, search distance (measured as km traveled/kill), and spatial use of recolonizing wolves (Canis lupus) in a multi-prey system in northwestern Montana, USA, and southeastern British Columbia, Canada, from 1986 to 1996. Our objective was to explore factors affecting these parameters to better understand wolf–prey relationships of recolonizing wolves. Within white-tailed deer (Odocoileus virginianus) winter ranges, wolves selectively killed elk (Cervus elaphus) over deer. Number of wolves (r = 0.67, P = 0.03), year (r = 0.68, P = 0.02), and possibly human hunter-days/elk harvested (r = 0.55, P = 0.08) were positively correlated with variation in proportion of deer killed by wolves annually. Outside of severe winters, white-tailed deer, elk, and moose (Alces alces) appeared to be equally vulnerable to wolf predation. Search distance of wolves varied by up to 12 times annually. Snow depth (r = 0.73, P = 0.03) and proportion of total kills by wolves that were deer (r = 0.66, P = 0.06) were negatively correlated with the annual variation in the total search distance of wolves. Search distance per wolf was correlated negatively with year (r = 0.66, P = 0.06) and exponentially with hunter-days/elk harvested (r = 0.70, P = 0.04). Space use by wolves may have been in response to local changes in deer abundance. Wolves appeared to select the most profitable prey species. Severe winters and wolf selection for deer, coinciding with a decrease in elk numbers, increased wolf hunting efficiency by reducing search distance. Further research is needed to determine whether reduced search distance equates to increased kill rates by wolves in this system. Based on the time, expense, and difficulty of gathering data on wolf search distance in this sytem, however, we recommend against assessing impacts of wolves on prey via measuring kill rate. Rather, we suggest monitoring impacts of recolonizing wolves by directly assessing cause-specific mortality and recruitment rates of prey species.

Many studies have been conducted on the ecology of raccoons (Procyon lotor), while few have examined raccoon den-site selection, particularly in agricultural and prairie landscapes. Furthermore, no studies have examined selection of den sites at multiple spatial scales. We examined den-site selection for 48 raccoons during 1997–1999 in an agricultural landscape in the Black Prairie physiographic region of east-central Mississippi, USA. Den types selected by raccoons differed by gender and season. Females used more cavity dens during young rearing, whereas males selected ground dens and brush piles. We found that den sites were located closer to crop fields, roads, and macrohabitat edges than random points. At the landscape level, den sites were associated positively with woody patch size, amounts of woody and grass edge, number of available patches of crop fields, and available area of lakes and ponds. Composition of habitats around den sites differed from composition of habitats within home ranges, and this difference also was noted by gender. Female raccoons selected crop fields, whereas males selected lakes/ponds relative to composition of habitats within their respective home ranges. Our results indicate the importance of tree cavities to females during young rearing, particularly on prairie landscapes. Furthermore, our findings suggest that on prairie landscapes, availability of foraging habitat and water may influence den-site selection. We suggest that raccoons select den sites based on a perceived arrangement of required resources and that landscape configuration is important in the den-selection process. Additionally, our findings offer evidence that managers may selectively remove den sites as a nonlethal means of managing predation by raccoons.

Prairie dog (Cynomys spp.) populations have been reduced by 98% compared to historical levels because of widespread poisoning, habitat loss, recreational shooting, and outbreaks of sylvatic plague (Yersinia pestis). Our objectives were to identify habitat correlates of Gunnison's prairie dog (C. gunnisoni) colonies and to develop a predictive logistic regression model to identify potential reintroduction sites for this species. During 2000 and 2001, we examined habitat features at 50 Gunnison's prairie dog colonies and 50 paired random sites in northern Arizona, USA. When compared to random sites, Gunnison's prairie dog colonies had deeper soils, less variability in slope, and less rock ground cover. Our results suggest the importance of deep soils for allowing Gunnison's prairie dogs to establish hibernacula below the frost line. Our model allows prediction of the probability of Gunnison's prairie dog presence at a site based on soil depth, standard deviation of slope, and surface rock cover, and should aid managers in reestablishing this species throughout its historical range.

The capture and handling of live European wild rabbits (Oryctolagus cuniculus) are unavoidable initial steps for immunization by vaccination against viral hemorrhagic disease (VHD) and myxomatosis as a management tool aimed at enhancing wild rabbit populations. We investigated the short-term effects of vaccination campaigns against VHD and myxomatosis on the survival of 206 European wild rabbits in a Spanish population. While no effect was observed on the survival of adult rabbits, young and subadult rabbits (P < 0.001) had higher mortality rates during the first week after handling than in the subsequent 3 weeks. The hazard rate of death from disease was inversely correlated with body condition (P < 0.001) during the first week. Vaccination increased the hazard rate of death due to disease during the first 7 days post-handling, although this detrimental effect was higher in young rabbits (P = 0.012) and modulated by body condition (P = 0.004). The hazard rate of dying from predation during the first week was higher for males than females (P = 0.023) and in subadults compared to young rabbits (P = 0.004). Body condition was inversely related to the predation hazard rate (P = 0.002). Our results suggest that vaccination campaigns had a short-term negative impact caused by the stress of handling in addition to the detrimental effects of vaccination against VHD and myxomatosis. Future studies should consider this negative impact to assess the true efficacy of vaccination campaigns in wild populations.

During the past decade, compositional analysis (CA) has been used widely in wildlife habitat and resource selection studies. However, critical aspects of CA have not been tested for potential systematic biases such as an inflated Type I error rate. We used computer-simulated data based on known habitat use and availability parameters and found that compositional analysis could result in large Type I error rates. These inflated Type I errors occurred when available habitat types that were not used by animals were included in the resource selection analysis. These error rates arise because of the recommended substitution of an arbitrarily small value, such as 0.01, for each 0% utilization value for any animal. We observed, based on a series of computer-simulation analyses, that progressively larger Type I error rates in CA resulted from substituting progressively smaller positive values for each 0% utilization of a habitat category. The Type I error rate in CA also increased when the number of experimental animals was increased for a fixed number of observations per animal. Two other resource selection analysis methods (Neu et al. [1974] and the Euclidean distance-based analysis [DA] method of Conner and Plowman [2001]) did not exhibit inflated Type I error rates for the same simulated data. Our computer simulations cause us to question the veracity of CA habitat selection analyses that include habitat patches or categories with relatively small areas of availabilities and 0% use.