The use of non-invasive DNA-based sampling is becoming increasingly popular. However, the misidentification of individuals due to genotyping error (primarily allelic dropout) is a critical problem, especially when using individuals in the capture–mark–recapture (CMR) approach to estimate population size. We propose 2 simple and cost-effective tests, Examining Bimodality (EB) and Difference in Capture History (DCH), to determine whether a sample contains genotyping errors and the relative magnitude of the problem. These tests formalize currently used approaches for identifying genotyping errors. We evaluate the efficacy of these tests using simulated CMR data. Results show that both tests are effective at detecting genotyping errors and provide a strong indication of whether the data are error free. The EB and DCH tests apply to data in which multiple samples are associated with individuals, such as those generated by CMR sampling. Managers need to be able to identify and eliminate genotyping errors to produce population estimates that are both unbiased and scientifically defensible.

McKelvey and Schwartz (2004, this issue) propose that the number of markers used to assign individual identity in DNA-based population inventories should be doubled or tripled relative to established practice, primarily to facilitate indirect statistical tests for genotyping errors. If applied to studies that use plucked hair samples, this suggestion would cause a proportional increase in the effort required to generate results, and an even greater increase in the number of errors initially present in those results. Since no empirical or deductive evidence was presented to show how established methods of selective reanalysis can fail to detect errors, I conclude that this proposal would dramatically increase costs without improving data quality. While the optimal number of markers will vary between study populations, I present 1 example in which identical results would have been achieved with 3 markers or with the 15 suggested by McKelvey and Schwartz (2004).

Capture–mark–recapture (CMR) estimates assume no misidentification of individuals captured and are extremely sensitive to identification errors. A large body of published literature has demonstrated that non-invasively derived genetic tags are error-prone, and the potential biases associated with these errors are large. We provided methods to reduce and evaluate these errors. Paetkau (2004, this issue), in his comments concerning our paper, argues that no formal, statistical error testing is necessary and that good laboratory practices are sufficient to remove all error. However, he provides only anecdotal evidence that this is the case. Given the presence of a variety of errors in genetic tags and the potential for large biases associated with these errors, we argue that scientific norms require formal tests to demonstrate the absence of errors. The primary purpose of our study was to provide such tests in a manner that is not cost-prohibitive.

Over a 3-year period, we assessed 2 sampling designs for estimating grizzly bear (Ursus arctos) population size using DNA capture–mark–recapture methods on a population of bears that included radiomarked individuals. We compared a large-scale design (with 8 × 8-km grid cells and sites moved for 4 sessions) and a small-scale design (5 × 5-km grid cells with sites not moved for 5 sessions) for closure violation, capture-probability variation, and estimate precision. We used joint telemetry/capture–mark–recapture (JTMR) analysis and traditional closure tests to analyze the capture–mark–recapture data with each design. A simulation study compared the performance of each design for robustness to heterogeneity bias caused by reduced capture probabilities of cubs. Our results suggested that the 5 × 5-km grid cell design was more precise and more robust to potential sample biases, but the risk of closure violation due to smaller overall grid size was greater. No design exhibited complete closure as estimated by JTMR. The results of simulation studies suggested that CAPTURE heterogeneity models are relatively robust to probable forms of capture-probability variation when capture probabilities are >0.2. Only the 5 × 5-km designs exhibited this capture-probability level, suggesting that this design is preferred to ensure estimator robustness when population size is <100. The power of the CAPTURE model selection routine to detect capture probability variation was low regardless of sampling design used. Our study illustrated the trade-off between intensive sampling to ensure robustness and adequate precision of estimators while being extensive enough to avoid closure violation bias.

While searching for food, 1 black bear (Ursus americanus) may girdle 60–70 coniferous trees in a day during the spring months in western Washington, USA. Tree-bark peeling and subsequent foraging on sapwood can result in substantial economic losses for forest landowners. The supplemental feeding program, a nonlethal approach to minimize black bear damage by providing an alternative food source, was developed by the Washington Forest Protection Association (WFPA) in 1986. From 1998 to 2002, I studied the efficacy of this supplemental feeding program on the Olympic Peninsula. I selected 14 conifer stands of approximately 20 ha each for study. Mean pretreatment conifer damage on these sites in 1998 was 26% of trees. In March 1999, 1,000 trees were marked on 4 transects throughout each stand. Two feeding stations were installed on each of 7 randomly chosen stands in April of 1999, while no supplemental feed was supplied on the remaining 7 control stands. I found that bears damaged significantly more trees on control sites than on treatment sites (P < 0.001). To validate initial results, I removed feeding stations from 2 of the 7 feeding sites in July 2000. Damage increased by a factor of nearly 7 on 1 feeding site over the next 2 years. I concluded that the supplemental bear feeding program constituted a viable, nonlethal damage control tool.

We studied the resting habitat ecology of fishers (Martes pennanti) in 2 disjunct populations in California, USA: the northwestern coastal mountains (hereafter, Coastal) and the southern Sierra Nevada (hereafter, Sierra). We described resting structures and compared features surrounding resting structures (the resting site) with those at randomly selected sites that also were centered on a large structure. We developed Resource Selection Functions (RSFs) using logistic regression to model selection of resting sites within home ranges, and we evaluated alternative models using an information–theoretic approach. Forty-five fishers were radiomarked, resulting in 599 resting locations. Standing trees (live and dead) were the most common resting structures, with California black oak (Quercus kelloggii) and Douglas-fir (Psuedotsuga menziesii) the most frequent species in the Sierra and Coastal study areas, respectively. Resting structures were among the largest diameter trees available, averaging 117.3 ± 45.2 (mean ± SE) cm for live conifers, 119.8 ± 45.3 for conifer snags, and 69.0 ± 24.7 for hardwoods. Females used cavity structures more often than males, while males used platform structures significantly more than females. The diversity of types and sizes of rest structures used by males suggested that males were less selective than females. In the Sierra study area, where surface water was less common, we found almost twice as many resting sites as random points within 100 m of water. Multivariate regression analysis resulted in the selection of RSFs for 4 subsets of the data: all individuals, Sierra only, Coastal only, and females only. The top model for the combined analysis indicated that fishers in California select sites for resting with a combination of dense canopies, large maximum tree sizes, and steep slopes. In the Sierra study area, the presence of nearby water and the contribution of hardwoods were more important model parameters than in the Coastal area, where the presence of large conifer snags was an important predictor. Based on our results, managers can maintain resting habitat for fishers by favoring the retention of large trees and the recruitment of trees that achieve the largest sizes. Maintaining dense canopy in the vicinity of large trees, especially if structural diversity is increased, will improve the attractiveness of these large trees to fishers.

Understanding population vital rates is fundamental to the evaluation of conservation options for wolverines (Gulo gulo). We estimated survival rates and causes of wolverine mortality in trapped and untrapped populations within montane, boreal, and tundra environments using data from 12 North American radiotelemetry studies conducted between 1972 and 2001. Rates were based on data for 62 mortalities of 239 radiomarked wolverines. Mortalities included 22 wolverines that were trapped or hunted, 3 road or rail killed, 11 that were predated, 18 that starved, and 8 deaths of unknown cause. Annual survivorship rates were estimated for sex and age class using Kaplan-Meier staggered-entry techniques. Survival was substantially lower in trapped (<0.75 for all age–sex classes) than in untrapped (>0.84 for all age–sex classes) populations. Human-caused mortality was mostly additive to natural mortality for wolverines in a management context. Logistic growth rate estimates indicated that trapped populations would decline (λ ≅ 0.88) in the absence of immigration from untrapped populations (λ ≅ 1.06). We recommend a system of spatial harvest controls in northern, continuous populations of wolverines and reduction of harvest along with more spatially explicit conservation measures in southern metapopulations.

In October 1995, a wildlands fire burned 5,000 ha on the Point Reyes peninsula, California, USA. In most of the nonforested areas, the fire effectively cleared the ground of litter and vegetation and revealed thousands of Point Reyes mountain beaver (Aplodontia rufa phaea) burrow openings. In the first 6 months after the fire, we surveyed burned coastal scrub and riparian habitat to (1) count the number of burrow openings that existed at the time of the fire, and (2) evaluate whether signs of post-fire mountain beaver activity were evident. We estimated that only 0.4–1.7% of mountain beavers within the burn area survived the fire and immediate post-fire period. We monitored mountain beaver activity for 5 years at 8 sites where mountain beavers survived, and found little or no recovery. We estimate that the mountain beaver population will take 15–20 years post-fire to recover.

Fox squirrel (Sciurus niger) populations are declining in the southeastern United States, presumably as a function of habitat loss. Because the ecology of southeastern subspecies of fox squirrels differs greatly from their well-studied midwestern relatives, habitat studies of midwestern fox squirrels are of limited use for managing southeastern subspecies. Therefore, we initiated a radiotelemetry study to evaluate habitat use of fox squirrels (n = 101) in southwestern Georgia, USA. Our results indicated that sex of fox squirrels and season did not affect habitat use and that fox squirrels did not display habitat selection within the home range. However, when selecting a home range, fox squirrels preferred mature pine (Pinus spp.) and mixed pine–hardwood forests and avoided hardwood forests. To provide fox squirrel habitat in southeastern pine landscapes, management strategies should maintain mixtures of mature longleaf pine (P. palustris) and mature mixed pine–hardwood forests.

In the southeastern United States, supplemental feeding of northern bobwhites (Colinus virginianus) is a common management practice. To determine whether bobcats (Lynx rufus) are attracted to supplemental food provided to northern bobwhites and whether this food affects bobcat home-range size, we radiomarked bobcats and assessed space use relative to supplemental feeding. We found little evidence to suggest that bobcat home-range sizes were affected by the supplemental food, but we observed bobcats to be approximately 10 times closer to supplemental food than expected under a null model. Our data suggest that supplemental feeding of prey can result in a spatial response by predators. Further research is needed to determine whether supplemental feeding of prey attracts other top predators and whether supplemental feeding results in decreased prey survival by attracting predators.

Knowledge of how predation risk affects population survivorship is important for understanding predator–prey relationships and designing effective conservation strategies. The Allee effect (inverse density dependence) can be generated when antipredator strategies become inefficient in small groups of prey, thus making the population more susceptible to catastrophic population collapse and extinction. Many populations of desert bighorn sheep (Ovis canadensis) are declining, and predation is, in many cases, a major mortality factor. We studied desert bighorns at the Red Rock Wildlife Area, New Mexico, USA, to assess predation risk in different group types (ram, ewe, mixed) and age–sex classes. Multiple regression analysis revealed that predation risk (as estimated by individual vigilance) increased with smaller group size and greater inter-individual distance for all bighorns, with groups of <5 individuals subject to the greatest risk. Although rugged terrain is thought to provide refuge from predators, habitat ruggedness did not influence vigilance. The biggest males in ram groups experienced the greatest predation risk in that they were in the smallest groups, were most likely to be solitary, and were spaced farther apart from conspecifics. Although big rams spent twice as much time vigilant as other age–sex classes, collective alertness was lowest for ram groups. The conclusion that big rams were most at risk from predation was partially supported by the recent predation history of the population and previous studies in which mountain lion (Felis concolor) kills were biased toward rams. We discuss the management implications of these results for small populations subject to Allee effects, including reintroduction and/or translocation practices and selective removal of problem predators. We suggest that the use of multivariate techniques to simultaneously explore the influence of multiple factors and the use of vigilance as a correlate of predation risk would be useful management tools for assessing seasonal and class-specific vulnerability to predation.

Risk of predation may affect individuals in prey populations by limiting their use of high-quality habitat. Predation risk, however, cannot be implicated as a factor in habitat selection by prey without data comparing quality of selected and avoided habitats, along with the predation risk associated with those habitats. If forage benefits and predation risk are not positively correlated among habitat types, then predation risk may have little influence on the habitat selected by prey. We evaluated habitat selection by mountain lions (Puma concolor) and mule deer (Odocoileus hemionus) in the eastern Sierra Nevada, California, USA, from 1994 to 1997, to determine how forage benefit or risk of predation by mountain lions affects habitat selection by mule deer. Mountain lions were the primary predator of mule deer in our study area. Stands of bitterbrush (Purshia tridentata) in the Great Basin provided more cover for mule deer than surrounding patches of rabbitbrush (Chrysothamnus nauseosum) or desert peach (Prunus andersonii). Bitterbrush also was important forage for mule deer during winter. We hypothesized that mountain lions would be more successful at stalking and killing mule deer in habitats with more concealment cover than in habitats with less cover, and therefore mule deer would choose between foraging on bitterbush and avoiding predation by mountain lions. We collected data on habitat characteristics in 3 types of locations: random locations (n = 180), deer foraging locations (n = 179), and locations where mountain lions killed deer (n = 41). Mule deer selected habitat at greater elevations (P < 0.001) with more bitterbrush (P < 0.001) and less rabbitbrush (P = 0.033) when compared with random locations. Logistic regression indicated that mountain lions killed deer in relatively open areas with more desert peach (P < 0.001) than at locations in which deer foraged. Therefore, deer were not confronted with a trade-off when selecting habitat on winter range, and they minimized the ratio of predation risk to forage benefit by selecting habitat with more bitterbrush. Changes in diet among seasons, which occur for herds of migratory deer, lead to individuals experiencing changing predation risk to forage benefit ratios throughout the year. Hence, migratory populations of mule deer likely adopt different strategies of habitat selection among seasons.

Mule deer (Odocoileus hemionus) fawn:doe (f:d) ratios in December have declined by 0.015 fawns/doe/year from 1972 through 1995 in Colorado, USA. To determine whether lower pregnancy or fetal production was the cause of low December f:d ratios, we estimated mule deer pregnancy rates in the Poudre River drainage during January 1998 and pregnancy and fetal rates on the Uncompahgre Plateau during February 1999. Twenty-seven (93.1%) of 29 yearling and adult does in the Poudre River drainage were detected pregnant with pregnancy-specific protein-B (PSPB). This proportion did not differ (P > 0.2) from the proportion of yearling and adult does that were pregnant when collected by various methods in previous studies in Colorado. Thirty-six (90%) of 40 adult does were detected pregnant with PSPB, and 37 (93%) of these 40 does on the Uncompahgre Plateau were detected pregnant with ultrasound. Proportion of adult does detected pregnant with ultrasound did not differ (P > 0.07) from pregnancy rate of adult does collected by various methods in previous studies. Average number of fetuses per doe for all adult does (pregnant and nonpregnant) on the Uncompahgre Plateau (n = 40, x̄ = 1.70, SE = 0.109) was not less (P > 0.06) than for adult does collected by various methods in previous studies. We concluded that failure to breed or maintain pregnancy through at least early January or early February does not appear to be the cause of low f:d ratios observed in Colorado.

Declining mule deer (Odocoileus hemionus) populations resulting from apparent low recruitment brought management and political focus on neonatal fawn survival. We captured mule deer fawns on the Uncompahgre Plateau (5,957 km²) in west-central Colorado, USA, at a mean age of 3 days (range = newborn to 6 days), and we radiomarked them with mortality-sensing, drop-off radiocollars. We radiomarked 230 fawns with samples of 50 in 1999, 88 in 2000, and 92 in 2001. Designated neonate survival period was from capture to 14 December. Survival was different among years (χ₂² = 6.160, P = 0.046) with 3-year mean survival of 0.501. Cause-specific mortality ordered from highest to lowest was sick/starve, coyote, unknown, trauma, bear, and feline. Neither all predation combined (coyote, bear, feline; P = 0.379) nor coyote predation alone (P > 0.989) differed among years. By 31 July, 74% of the sick/starve mortality and 75% of the predation mortality had taken place, with 76% of mortality from all sources occurring by this date. Mean fawn weights at capture were different among years (P = 0.044). We also found a difference in hind-foot length among years (P = 0.002). Weight and hind-foot means were different between 2000 and 2001 (P > 0.017), with 1999 not different from either 2000 or 2001 (P < 0.017). Mean capture date was 19 June (SD = 4.83 days) and median capture date was 19 June (range = 9 Jun–6 Jul), with 94.8% of all captures occurring between 13 and 30 June. This implies that most does were bred during their first estrus cycle. Neonatal survival through 14 December did not completely account for observed low fawn:doe (f:d) ratios. We hypothesized that fetus mortality during late pregnancy or mortality of fawns at birth (before they could be detected for capture) as potential causes of poor recruitment.

We studied population structure and limiting factors within a desert mule deer (Odocoileus hemionus eremicus) population in Brewster County of the Trans-Pecos Region in Texas, USA. We estimated and compared annual survival and pregnancy rates from March 1990–February 1993 for 121 adult (>33 months old) male and female, 61 subadult (21–33 months old), and 77 young (8–20 months old) deer. Variation in weather patterns (i.e., drought) was associated with—if not causative of—annual variation in survival patterns. Adult female and young survival had the strongest correlation with drought. Pregnancy status of young (≤1.5 yr) and old (≥6.5 yr) deer appeared most affected by drought. Seasonal periods of natural stress differed for adult sex classes, with most female mortalities occurring during months associated with parturition and lactation, and most male natural stress losses occurring during late winter and early spring. The major mortality sources were hunting and natural stressors for adult males, natural stressors and predation for adult females, and predation and natural stressors for young. Subadult mortalities were too few to identify significant mortality agents. The significance of natural stress-related survival and fecundity impacting herd productivity and stability warrants further consideration of poorly understood causative mechanisms. Ideally, replicated treatment areas would be used to address compensatory and additive mortality issues relative to predator abundance, harvest, and natural-stress losses.

With decreased illegal hunting and better habitat conservation, the Florida Key deer (Odocoileus virginianus clavium) population grew from an estimated 25–50 animals in the late 1940s to approximately 200 animals on Big Pine and No Name keys, Florida, USA, by 1971, the last official survey. U.S. Fish and Wildlife Service (USFWS) trend data indicate that the deer population continued to increase after 1971; however, current deer density estimates are necessary for the proposed reclassification of the Key deer from endangered to threatened. Our study objectives were to (1) obtain current population estimates of Florida Key deer and compare these to historical estimates, (2) evaluate survey methods (USFWS mortality and deer counts) in detecting changes in population trends, and (3) outline a protocol for future monitoring. Road counts (n = 889) were conducted from January 1971 to December 1971 and January 1976 to December 2001 on Big Pine and No Name keys. From mark–recapture data, we estimated that the Key deer population on these 2 islands increased by 240% between 1971 and 2001 (2001 estimate: 453–517 deer). Trend data indicated that annual deer mortality was a function of deer density or population size (r_s = 0.743). We compared the annual finite rate of increase (R) from USFWS annual deer counts and mortality data (R = 1.053–1.065) to mark–recapture studies (R = 1.038) and found them to be similar (P = 0.66–0.67). This similarity suggests that all 3 methods (USFWS deer counts and mortality data, and mark–recapture data) can be used to monitor changes in Key deer density.

Application of Habitat Suitability Index (HSI) models without testing in areas other than where they were generated, and claims that habitat preferences have been proven, indicate that managers and scientists believe that habitat preferences of wildlife are fixed. We tested this hypothesis by comparing habitat preferences of 2 groups of moose (Alces alces) in northeastern Alberta, Canada, to which the same habitat classes were available but differed in relative abundance. We estimated habitat availability for each of 22 radiomarked, adult female moose and divided the animals into 2 groups based on the similarity of relative habitat class abundances. We measured habitat preference for individual moose from each group during 2 seasons in each of 2 years using a simple resource selection function (RSF). We used analysis of variance (ANOVA) to compare differences between groups. Preference of several habitat classes differed between groups, indicating that habitat preferences of moose are not fixed and change as the relative abundance of available habitat changes. Managers must recognize and account for this concept in the application of habitat prescriptions or management plans.

State-dependent strategies (SDSs) are the most general form of harvest policy because they allow the harvest rate to depend, without constraint, on the state of the system. State-dependent strategies that provide an optimal harvest rate for any system state can be calculated, and stochasticity can be appropriately accommodated in this optimization. Stochasticity poses 2 challenges to harvest policies: (1) the population will never be at the equilibrium state; and (2) stochasticity induces uncertainty about future states. We investigated the effects of 2 types of stochasticity, environmental variability and management control error, on SDS harvest policies for a white-tailed deer (Odocoileus virginianus) model, and contrasted these with a harvest policy based on maximum sustainable yield (MSY). Increasing stochasticity resulted in more conservative SDSs; that is, higher population densities were required to support the same harvest rate, but these effects were generally small. As stochastic effects increased, SDSs performed much better than MSY. Both deterministic and stochastic SDSs maintained maximum mean annual harvest yield (AHY) and optimal equilibrium population size (N_eq) in a stochastic environment, whereas an MSY policy could not. We suggest 3 rules of thumb for harvest management of long-lived vertebrates in stochastic systems: (1) an SDS is advantageous over an MSY policy, (2) using an SDS rather than an MSY is more important than whether a deterministic or stochastic SDS is used, and (3) for SDSs, rankings of the variability in management outcomes (e.g., harvest yield) resulting from parameter stochasticity can be predicted by rankings of the deterministic elasticities.

Gambel oak (Quercus gambelii) is a valuable tree species for wildlife. In Arizona, USA, it occurs at higher elevations in association with ponderosa pine (Pinus ponderosa). Southwestern myotis (Myotis auriculus) is a bat species that has been anecdotally documented as selecting Gambel oak for maternity roost sites. During summers of 1999 and 2000, we conducted a radiotelemetry study to determine whether lactating, female southwestern myotis selected Gambel oak as maternity roosts within the ponderosa pine–Gambel oak forest in northern Arizona. We located 34 maternity roosts for southwestern myotis in Gambel oak trees (14 females) and 5 roosts in ponderosa pine snags (1 female). Maternity roosts were located in live Gambel oak trees >26-cm diameter at root collar (drc) that contained cavities. We used Akaike's Information Criterion (AIC) to evaluate 4 a priori hypotheses about southwestern Myotis maternity roost selection in northern Arizona. Our top model contained parameters for roost tree height and density of potential roost trees. Roost trees were taller than randomly selected Gambel oak trees. Forest patches immediately surrounding roost trees contained a higher density of large oak trees (drc >26 cm) than around randomly selected trees. We recommend the protection of large Gambel oak trees and encourage recruitment of large Gambel oak trees from smaller size classes to ensure that roosts remain available for southwestern myotis.

Although only 2 bat species are common in the Greater Fundy National Park Ecosystem of New Brunswick, Canada, 4 distinct groups occur in terms of roost-site selection due to sexual segregation. We found that female northern long-eared bats (Myotis septentrionalis) roosted alone or as part of maternity colonies in mature, shade-tolerant deciduous stands. A roost site was 24 times more likely to be in a shade-tolerant deciduous tree than a coniferous tree, and trees in the mid-decay classes were 5.2 times more likely to be used than live or recently dead trees. Male northern long-eared bats roosted alone in coniferous stands or conifer-dominated mixedwood stands, and they selected roost trees that were in the mid-decay stages. Trees in mid-decay stages were selected more than twice as often as trees at the early or late stages of decay. For every 10% increase in the proportion of coniferous trees in the plot, the chances of a male northern long-eared bat roosting in the plot increased 1.5 times. Female little brown bats (M. lucifugus) in our study area were transients. Male little brown bats primarily roosted alone in coniferous stands, or conifer-dominated mixedwood stands. Their selection of roost sites was highly dependent on the number of snags in the vicinity. For every increase of 5 snags in a 0.1-ha plot, the odds of use for male little brown bats on that site increased by 2.5 times. The long-term availability of roost sites for males of both species in our study area may be linked to spruce budworm (Choristoneura fumiferana) epizootics, which is the major mortality factor for coniferous species in the region. Female northern long-eared bat roosts probably are more consistantly available because suitable sites are created by continuously occurring, individual-tree stressors in mature shade-tolerant forests.

Reliable estimates of trends in population size are critical to effective management of landbirds. We propose a standard for considering that landbird populations are adequately monitored: 80% power to detect a 50% decline occurring within 20 years, using a 2-tailed test and a significance level of 0.10, and incorporating effects of potential bias. Our standard also requires that at least two-thirds of the target region be covered by the monitoring program. We recommend that the standard be achieved for species' entire ranges or for any area one-third the size of the temperate portions of Canada and the United States, whichever is smaller. We applied our approach to North American Breeding Bird Survey (BBS) data. At present, potential annual bias for the BBS is estimated at ±0.008. Further, the BBS achieves the monitoring standard for only about 42% of landbirds for which the BBS is considered the most effective monitoring approach. Achieving the proposed monitoring target for ≥80% of these species would require increasing the number of BBS—or similar survey—routes by several-fold, a goal that probably is impractical. We suggest several methods for reducing potential bias and argue that if our methods are implemented, potential bias would fall to ±0.003. The required number of BBS or similar routes would then be 5,106, about 40% more than in the current BBS program. Most of the needed increases are in 15 states or provinces. Developing a comprehensive land-bird monitoring program will require increased support for coordination of the BBS (currently 2 people) and new programs for species that are poorly covered at present. Our results provide a quantitative goal for long-term land-bird monitoring and identify the sample sizes needed, within each state and province, to achieve the monitoring goal for most of the roughly 300 landbird species that are well suited to monitoring with the BBS and similar surveys.

Chronic marine oil pollution is an ongoing global problem, yet no model currently exists to assess seabird mortality from continuous low-level inputs of oil. Taking into account persistence and detection rates of birds on beaches, and the wind-dependent proportion of birds lost at sea, we present a general mathematical Oiled Seabird Mortality Model (OSMM) to assess seabird mortality due to chronic oil pollution along a given coastline, using birds counted during systematic beached-bird surveys. We applied our OSMM to Newfoundland, Canada, where the incidence of chronic oil pollution is among the highest in world. We estimated that between 1998 and 2000, an average of 315,000 ± 65,000 murres (common [Uria aalge] and thick-billed [U. lomvia]) and dovekies (Alle alle) were killed annually in southeastern Newfoundland due to illegal discharges of oil from ships. Thick-billed murres that overwinter on the Grand Banks made up 67% of this kill. This species already is subject to extensive summer and winter hunting in Greenland, as well as winter hunting in Newfoundland, which harvests an additional 250,000–300,000 birds/year. Although populations remain stable, these levels of sustained mortality make thick-billed murre populations vulnerable to pulse perturbations and ocean regime shifts and hamper our ability to set harvest at sustainable levels.

Accurate and precise estimation of the size of animal populations is critical to sound management and conservation. The size of the greater snow goose (Chen caerulescens atlantica) population has been monitored since 1965 by means of an aerial photographic survey conducted every spring in southern Quebec, Canada. As the population increased, the estimation of its size evolved from total counts of the birds on photographs (1965–1990) to sampling the photographed flocks (1991–2000). From 1998 to 2000, we implemented a protocol to estimate the proportion of flocks missed by the photographic survey. This was achieved using radiomarked geese that were tracked by independent observers during the aerial survey. The proportion of radiomarked geese detected during the survey was used to estimate the proportion of the population that was photographed. The estimated size of the photographed population was based on a combined stratified ratio estimator using partial counts and visual estimates of flocks in 3 size classes. The estimated size of the photographed population had a coefficient of variation (CV) of 2–6%. This precision was achieved by counting only 15% of the photographed geese on average, which was a large gain in logistical efficiency considering the size of the population. We found no evidence for overdispersion of the number of radiomarked birds (n = 70 in 1998, n = 41 in 2000) encountered in each flock. In 1999, technical problems with radiotransmitters prevented a reliable total population size estimate. In 1998 and 2000, we estimated that the photographic crew missed 11 and 29%, respectively, of the radiomarked geese present. The CV of the total population size estimates were 5.8% in 1998 and 11.1% in 2000. As the proportion of missed flocks increases, the number of radiomarked birds required to obtain a CV of 5% increases with a concomitant increase of cost. We highlight spatial and temporal changes in the spring distribution of greater snow geese staging in southern Quebec and suggest that adjustments of timing and coverage of the surveys will be required to maintain and improve the accuracy of the population size estimates at low cost.

In 1990–1992, we studied predation of waterfowl nests by mammalian predators on 30 islands in a 64-km reach of the Snake River in southwestern Idaho, USA, to identify river flows necessary to protect and enhance migratory bird use of Deer Flat National Wildlife Refuge. We monitored 235–314 Canada goose (Branta canadensis) nests each year and 122 duck nests, primarily mallard (Anas platyrhynchos), in 1991. We calculated island isolation as the flow energy (width × average water velocity [m²/sec]) a predator encountered in crossing to an island. Density of goose nests increased as island isolation increased (P < 0.001). In contrast, visits of terrestrial predators to islands, mammalian predation of goose nests, and variance in predation rates decreased as island isolation increased (P < 0.01). Nests were most frequently depredated by raccoons (Procyon lotor), coyotes (Canis latrans), badgers (Taxidea taxus), and mink (Mustela vison). Multiple regression models explained 67% of the variance in nest density and 48% of variance in predation rates (P < 0.01). Variables of secondary importance relative to island isolation were island size and percentage of farmland on the adjacent mainland. Fewer geese nested (P < 0.01) and predation rates were greater (P = 0.06) on large islands, and more geese nested on islands adjacent to farmland (P = 0.04). We also analyzed rates of nest predation relative to river flows for 21 islands from 1953 to 1992. Mammalian predation of goose nests decreased as island isolation increased with greater river flows (P < 0.01). To identify levels of isolation needed to protect use of islands by nesting waterfowl, we estimated rates of change in nest densities and predation rates with island isolation for a range of regression quantiles. We then calculated levels of island isolation at river flows ranging from 110 to 340 m³/sec. Below flows of 250 m³/sec, nest predation rates increased rapidly. Flows ≥340 m³/sec adequately isolated Snake River islands for nesting waterfowl. Predator visitation and nest predation rates were at a low level, and variability in the rates was at a minimum for these flows.

We present descriptive data on survival and cause-specific mortality of northern bobwhites (Colinus virginianus) in western Oklahoma, USA, during 1991–2002. We captured and radiomarked 2,647 bobwhites (286 adult [ad] M, 1,064 juvenile [juv] M, 185 ad F, and 1,049 juv F) to obtain estimates. We estimated that annual survival (Nov–Oct) averaged 0.068 ± 0.018 (SE) and ranged between 0.018 ± 0.048 and 0.211 ± 0.038. We pooled data over the study period and found that sex–age classes survived at similar rates. We estimated average annual isolated rates of bobwhite mortality (rates in the absence of other causes) to be 0.63 ± 0.027 from raptor predation, 0.45 ± 0.021 from mammal predation, and 0.45 ± 0.043 from harvest. Under the additive theorem of probability, the isolated rates translated to an average annual mortality rate of 0.88 ± 0.017. The bobwhite population had variable and sometimes low survival in November–February inclusive. Low monthly survival (<0.5, n = 7) during winter was due primarily to harvest (0.57 ± 0.099 losses/known-fate individual) and raptor predation (0.25 ± 0.051 losses/known-fate individual). We discuss evidence indicating that radiotransmitters handicapped bobwhites and resulted in survival estimates biased low and to uncertainty in interpretation of cause-specific mortality.

Researchers have indexed abundance of the northern bobwhite (Colinus virginianus; hereafter, bobwhite) during autumn by counting the number of coveys heard during early morning call surveys. However, critical assumptions about call rates, survey timing, and seasonality have not been tested, and the effects of weather and bobwhite density on call rates are unknown. Therefore, we quantified covey-calling activity of 219 radiomarked coveys at 5 sites during September–December 1997–1999 to assess the effects of these variables. Across all sites, the average proportion of coveys that called prior to leaving the roost site was 58% (range = 48–87%). Coveys began calling 23.4 ± 0.5 (x̄ ± SE) min before sunrise, and they produced 31.4 ± 1.9 calls/call event; most calls (87%) occurred 35–15 min before sunrise. Using data collected in 1998, we fit 15 logistic regression models to predict the probability of a covey calling. The selected best model (Akaike weight [w] = 0.48) included variables for the number of adjacent calling coveys, wind speed, cloud cover, and barometric pressure change with number of adjacent calling coveys having the greatest effect on covey calling (odds ratio of 1.4). A less parsimonious model, which also included biweekly periods and interaction terms, was potentially as likely (w = 0.41) as the selected model, with the 16–31 October biweekly period having most effect (odds ratio of 1.8) over other biweekly periods. We tested selected best models using observations collected in 1999 from 2 of the sites monitored in 1998. During peak calling periods, predicted call rates were <0.06 from observed covey-call rates. Given the accuracy of predicted call rates, we recommend adjusting covey-call counts by an estimated calling rate to better measure fall bobwhite abundance.

We studied year-round food preferences of the three-toed woodpecker (Picoides tridactylus) from 1994 to 2000 in Berchtesgaden National Park, Germany. We color-banded 52 birds for individual recognition, and we radiomarked 25 adults from this sample. We analyzed 142 feces of 30 adults and 588 feces of 40 nestlings from 15 nests. Additionally, we took samples from 20 trees recently used for foraging in 10 woodpecker territories to estimate local prey availability. Based on relative abundance and relative frequency of food items (i.e., importance value), overall diet composition of adult three-toed woodpeckers was dominated by spiders (Araneidea), larvae of longhorn beetles (Coleoptera, Cerambycidae), and bark beetles (Coleoptera, Scolytidae). Adults ate longhorn beetle larvae primarily during nesting, while imagines (fully developed adults) and larvae of various bark beetles appeared to be the main food resource outside the nesting season. Nestling diet was dominated by spiders and longhorn beetle larvae that were gathered 247 ± 122 m (x̄ ± SD) from the nest. Our results demonstrated that consumption of bark beetles by three-toed woodpeckers varies throughout the year, being lowest during the nesting season, while longhorn beetle larvae are preferred throughout the year. Securing habitat requirements of both bark and wood-boring beetle communities is a critical step to maintaining viable three-toed woodpecker populations.

Few if any studies have examined the influence of a recently implemented hunting season on harvest characteristics of mourning doves (Zenaida macroura). We conducted a reward banding study in Ohio, USA, during 1996–1998 to compare harvest rates in urban and rural areas and to estimate overall harvest rate and band-reporting rate. Estimates from band-recovery models provided strong evidence for site- and year-specific variation in harvest rates of doves captured at urban and rural sites. Annual harvest-rate estimates ranged from 0.006 (95% CI: 0.001 to 0.011) to 0.011 (95% CI: 0.005 to 0.018) for birds captured at urban sites, and from 0.034 (95% CI: 0.022 to 0.045) to 0.054 (95% CI: 0.039 to 0.069) for birds captured at rural sites. The estimated reporting rate of 0.208 (95% CI: 0.142 to 0.274) was less than previously published estimates, probably because of a lack of familiarity of hunters with dove bands. In our study, >80% of the harvest of banded birds occurred in Ohio, suggesting that hunting pressure on this population is largely determined by Ohio hunters. Increased understanding of the role of urban landscapes as potential refuges from hunting pressure will improve our ability to manage dove harvests. Large-scale banding studies are needed to obtain contemporary estimates of harvest parameters, which are necessary for more informed harvest management of mourning doves.

More than 4 million farm-reared red-legged partridge (Alectoris rufa; hereafter partridge) are released each year in autumn for harvest purposes in Spain. We compared the helminth fauna of 122 juvenile, farm-reared partridge from 9 farms around Spain with that of 174 wild partridge from 7 harvest areas where no releases currently are conducted. We examined the digestive tract, liver, and trachea. Fourteen helminth species were retrieved (6 from farm-reared partridge, 9 from wild partridge). No trematode or nematode species were shared by both groups of partridge, and only 1 cestode species was present in both populations. Monoxenous nematodes were the most prevalent species found in farm-reared birds. Ascaridia compar, a parasite of the rock partridge (A. graeca) previously unreported in the red-legged partridge, was found in 4 facilities. Heteroxenous helminths, such as Dicrocoelium sp., Raillietina tetragona, and Cheilospirura gruveli, predominated in wild partridge. The prevalence and intensity of helminths in some farmed partridge were higher than expected considering the routine use of antihelminthics in these facilities. Thus, released partridge may introduce new parasites into wild populations, come into contact with parasites of wild partridge, and be negatively affected by their parasite burdens after release. These risks require further study.

We assessed the effect of campgrounds on American crow (Corvus brachyrhynchos) populations on the Olympic Peninsula in Washington, USA, because crows are potential nest predators for marbled murrelets (Brachyramphus marmoratus). We measured resource use, home range, relative abundance, and reproduction for 39 crows in 13 campgrounds that varied in size and proximity to other sources of anthropogenic food. Campgrounds concentrated crow populations and individual resource use. However, campgrounds did not provide optimal conditions for reproduction. Instead, reproduction was highest for crows that accessed exurban areas surrounding campgrounds. Concentration of use in exurban lands by 6 crows that nested >5 km from camprounds or human settlements confirmed the far-reaching effects of human activity in this area on crows. We concluded that human settlements fueled crow population growth on the Olympic Peninsula, and remote campgrounds absorbed this growth through colonization. As exurban crow populations expand, campgrounds likely will experience increases in local abundance of crows. Our observations do not suggest that rising crow populations will reduce the nesting success of other birds near campgrounds, but crows may indicate the suitability of campgrounds to other human commensals. Managing food resources within campgrounds may be insufficient to curtail crow population growth. Instead, regional cooperation is needed to identify and reduce food sources at broad spatial scales to target source populations.

Golf is said to be among the most rapidly increasing forms of land use, yet little is known of the effects of golf courses and golf playing on wildlife. A Norwegian population of the endangered ortolan bunting (Emberiza hortulana) occurs on a forest burn that has an area allocated to golf. Some forest-burn habitat (heather [Calluna vulgaris] heath with scattered, small Scots pines [Pinus sylvestris]) remains between fairways and on the periphery of the golf course. I compared pairing success, residence times, and emigration rates of male ortolan buntings in the interior and periphery of the golf course and in a neighboring part of undisturbed forest burn (control area). Males in the interior of the golf course (n = 4) never attracted females and less than half (43%, n = 7) in the golf periphery did so, whereas most males in the control area attracted females (77%, n = 13; all males on golf course vs. control: P = 0.038). Males in the golf interior had shorter residence times than males on the golf periphery, and both were present for a shorter time than males in the control area (golf vs. control: P = 0.030). All males that had territories in the golf interior emigrated to other areas (median = 13.3 km away). The emigration rate was lower for males on the golf periphery (43%) and even lower in the control area (15%; golf vs. control: P = 0.033). Males emigrating from the golf course attracted females at the same rate as control males in their new areas of residence. Compared to males in the rest of the forest burn (n = 76), males on the golf course had shorter residence times (P = 0.049) and higher emigration rate (P = 0.009), but pairing success was not different (P = 0.196). Overall, the golf course did not seem to be attractive to ortolan buntings, although the lack of other populations on golf courses precludes replicate studies. Whether the apparent avoidance was due to fragmentation of breeding habitat on the golf course, human disturbance, or some other reason remains to be tested. In the case of the ortolan bunting, the negative effects of the golf course probably would have been reduced if remaining natural habitat had been concentrated to the periphery of the golf course and adjacent to other bunting habitat.

Aircraft collisions with wildlife (primarily birds) are costly in terms of injury or loss of human life, loss of the animals involved, damage to property and business, and the use of lethal control of wildlife at airports worldwide. One potential nonlethal technique to reduce bird–aircraft collisions—pulsed white and wavelength-specific aircraft-mounted light—has been considered for nearly 3 decades, but the efficacy of the technique has not been evaluated quantitatively. We tested the hypothesis that during daylight, captive birds exposed to an approaching ground-based vehicle exhibiting pulsing 250-W white aircraft landing lights would initiate avoidance behavior more quickly than birds experiencing an oncoming vehicle with nonpulsing (steady) or no lights (control). In experiments involving captive brown-headed cowbirds (Molothrus ater), Canada geese (Branta canadensis), European starlings (Sturnis vulgaris), herring gulls (Larus argentatus), and mourning doves (Zenaida macroura), only cow-birds exhibited a response to the landing lights, but not consistently. Specifically, cowbird groups (9 groups/treatment, 6 birds/group) responded more quickly to pulse versus control treatments, equating to a greater distance (x̄ ± SE) of the approaching vehicle from mid-cage per reacting bird (control: 35.8 ± 9.7 m, pulse: 50.5 ± 10.9 m; P = 0.015). However, in a subsequent experiment involving the exposure of cowbirds to control, pulse, and steady-light treatments, we observed no difference in response among treatment groups. Although 250-W white landing lights pulsed at 45 cycles/min influenced behavior of captive birds in response to an oncoming ground-based vehicle, the avoidance response was inconsistent across experiments with cowbirds, and we observed little or no avoidance behavior in experiments with other species. We suggest that further research is needed to investigate avian response to specific light wavelengths and pulse frequencies.