Worldwide human population expansion and rising standards of living place increasing pressure on wildlife populations and their habitats. Conflict regarding conservation and preservation of endangered species is among the greatest challenges of the 21st century. Endangered species management on private lands magnifies the problems encountered by natural resource policy-makers and managers. Given that conservation of endangered species increasingly depends on securing cooperation of private property owners in local communities, understanding how to secure that cooperation is important. We used an ethnographic approach to critically review the Habitat Conservation Plan (HCP) processes used in attempts to develop regional HCPs to benefit the Houston toad (Bufo houstonensis) and the Florida Key deer (Odocoileus virginianus clavium; hereafter, Key deer). In both cases, the process was framed as a search for the optimum solution through collaboration and consensus building, and in neither case was the solution achieved. The paradoxical nature of liberal democracy precluded the possibility of a single, ideal solution. Failing to find the optimal solution led to disillusionment and pessimism with the process among HCP participants. We suggest that within democratic political contexts, approaches to conservation planning that center around bounded conflict, which is rooted in acknowledgment of the paradox inherent to the ideals of liberty and equality, are more likely to produce satisfactory results than are consensus-based approaches.

Recreational hunting is the primary management tool used by natural resource agencies to control ungulate populations. Although free-ranging ungulates have been studied extensively in North America, relatively little is known about the field behavior of hunters or the factors that influence hunting behavior, except on small study areas where access is limited and controlled. We developed 3 integrated protocols to estimate hunter density, distribution, movements, habitat use, characteristics, and attitudes, which can be used on large areas with unrestricted access. We described how aerial surveys, in conjunction with distance sampling techniques and a Geographic Information System (GIS) database of landscape characteristics, provide estimates of hunter density and a map of hunter distribution and habitat use. We used Global Positioning System (GPS) units issued to hunters to systematically record hunter locations. Hunters also completed a simple questionnaire. We linked these data and used them to obtain detailed information on habitat use, movements, and activity patterns. Whereas aerial surveys are limited to discrete points in time and relate only to aggregations of hunters, data collected on hunters that carry GPS units can be used to study habitat use and distribution at different times of day for individual hunters. Finally, linked responses from a traditional mail or telephone survey to hunter location data collected via GPS units to assess how hunter characteristics (e.g., age, physical condition, attitudes) were related to field behavior. We applied these techniques during a white-tailed deer (Odocoileus virginianus) hunting season on a large tract (45,749 ha) of public land in Pennsylvania, USA, with unrestricted hunter access. We estimated density of 7 hunters/1,000 ha (95% CI: 4.2 to 10.3) in the morning and 6.3 hunters/1,000 ha (95% CI: 3.5 to 10.0) in the afternoon. We found that hunter density was negatively related to distance from roads and slope. Most hunters preferred stand hunting, especially in the early morning hours (0600–0800 hr; 72% stationary); more walked or stalked in the afternoon (1400–1600 hr; 58% stationary). The average maximum distance hunters reached from a road open to public vehicles was 0.84 km (SE = 0.03), and they walked an average of 5.48 km (SE = 0.193) during their daily hunting activities. We believe that the approaches we used for studying hunter behavior will be useful for understanding the connections between hunter attitudes and behavior and hence will allow managers to predict hunter response to changes in harvest regulations. Furthermore, our methods are more accurate than requesting hunters to self-report where they hunted. For example, we found that hunters reported that they walked >2.5 times farther from the nearest road (x̄ = 2.23 km, SE = 0.13) than actual distance recorded via GPS units (x̄ = 0.84 km, SE = 0.03). Our research provides wildlife managers with new knowledge on several levels. At the most basic level, we learned a great deal about what hunters actually do while in the field, rather than simply what they report. Second, linking field behavior with hunter characteristics will provide insights into the likely effects of changing hunter demographics. Finally, linking these data with traditional human-dimensions research topics, such as attitudes toward hunting regulations, may allow managers to better forecast the potential effects of regulation changes on hunter distribution and effort.

Logistic regression is an important tool for wildlife habitat-selection studies, but the method frequently has been misapplied due to an inadequate understanding of the logistic model, its interpretation, and the influence of sampling design. To promote better use of this method, we review its application and interpretation under 3 sampling designs: random, case–control, and use–availability. Logistic regression is appropriate for habitat use–nonuse studies employing random sampling and can be used to directly model the conditional probability of use in such cases. Logistic regression also is appropriate for studies employing case–control sampling designs, but careful attention is required to interpret results correctly. Unless bias can be estimated or probability of use is small for all habitats, results of case–control studies should be interpreted as odds ratios, rather than probability of use or relative probability of use. When data are gathered under a use–availability design, logistic regression can be used to estimate approximate odds ratios if probability of use is small, at least on average. More generally, however, logistic regression is inappropriate for modeling habitat selection in use–availability studies. In particular, using logistic regression to fit the exponential model of Manly et al. (2002:100) does not guarantee maximum-likelihood estimates, valid probabilities, or valid likelihoods. We show that the resource selection function (RSF) commonly used for the exponential model is proportional to a logistic discriminant function. Thus, it may be used to rank habitats with respect to probability of use and to identify important habitat characteristics or their surrogates, but it is not guaranteed to be proportional to probability of use. Other problems associated with the exponential model also are discussed. We describe an alternative model based on Lancaster and Imbens (1996) that offers a method for estimating conditional probability of use in use–availability studies. Although promising, this model fails to converge to a unique solution in some important situations. Further work is needed to obtain a robust method that is broadly applicable to use–availability studies.

The Przewalski's horse (Equus caballus przewalskii) became extinct in the wild in the 1960s. Since 1997, captive-bred horses have been released into the Gobi-B Strictly Protected Area (SPA) in southwestern Mongolia, and successful reproduction in the wild started in 1999. In 2002, the population formed 3 harem groups and 1 bachelor group (total 38) in the wild, and 3 harem groups (24) awaited release in summer 2003 within acclimatization enclosures, totaling 62 individuals. We used the stochastic population simulation model VORTEX to (1) identify key variables and their threshold values in population dynamics, (2) predict extinction risk, and (3) optimize project management and release regime by comparing model parameters with our population data. Maximum age of reproduction, foal mortality, and fecundity rates were key factors in population dynamics, while number of released animals, release interval, and duration of supplementation played lesser roles. The severity level of natural catastrophes had the greatest influence on extinction risk and population size according to VORTEX. Assuming a maximum reproductive age of 16 years, an initial population of >140 horses is necessary to achieve a 95% probability of survival over 100 years under the low-severity level of catastrophes scenario. The corresponding extinction risk for high-severity level of catastrophes is 37%, even for initial population sizes >500. The low natural growth rate of the Przewalski's horse may have been the essential prerequisite for extinction in this remote area of Mongolia. However, uncertainty of results was high and limits the predictive value of the model. Comparisons between model parameters with observed population characteristics over the past 10 years reveal some discrepancies that may require readjustment of the model if present trends continue. While our model currently underestimates reproductive rate and foal survival, adult mortality tends to be higher than estimated in the model. We believe that adult survival can be improved in the wild and that the reintroduction program has a realistic chance of success. We stress the importance of an intensive monitoring program of the Przewalski's horse population and consecutive modeling exercises to reevaluate success of this reintroduction program.

In northeastern Alberta, Canada, continued expansion of the oil and gas industry along with timber harvesting has raised concerns that the resulting environmental changes may negatively affect the woodland caribou (Rangifer tarandus caribou) population in this region. Caribou are a threatened species in Alberta, and populations in northeastern Alberta appear to be stable or slightly decreasing. The spatial distribution of caribou in relation to alternative prey (commonly moose [Alces alces]) has been hypothesized to affect the level of wolf (Canis lupus) predation on caribou populations. We monitored radiomarked caribou, moose, and wolves between 1993 and 1997, and we found that selection of fen/bog complexes by caribou and selection of well-drained habitats by moose and wolves resulted in spatial separation. This spatial separation in turn reduced wolf predation pressure on caribou but did not provide a total refuge from wolves. Any management activities that increase the density of moose and wolves or increase access of wolves into fen/bog complexes will likely reduce the refuge effect provided by large fen/bog complexes.

We fit data on elk (Cervus elaphus) population size and composition, survival rates measured from their first week of life, reported harvest, and local weather to a series of alternative population models of the elk herd in Jackson, Wyoming, USA, for the period 1980–2002. Data were corrected for biases in aerial survey visibility, misclassification of juveniles in ground surveys, and harvest reporting. The models included explanatory variables for sex, age, population size, weather, and autocorrelation of survival rates in different periods. Using information–theoretic model selection, we identified the most strongly supported models and effects. Model complexity ranged from 12 to 70 fitted parameters, and the best-supported model contained 25 parameters. We estimated annual natural survival (excluding harvest) of mature (≥1 yr) elk of 96.8% (SE = 1.5%) for males and 97.2% (SE = 2.2%) for females. Natality was 60.4 juveniles/100 mature females (SE = 3.9 juveniles/100 mature females). Sex ratio at birth strongly favored females (45.8% males, SE = 1.6%, Akaike weight = 99.9%). The dynamics of this population were well explained by annual variation in survival of neonates (birth to 31 Jul), juvenile survival during late winter (20 Feb–19 May), and harvest. Survival of neonates was correlated with several weather covariates that apparently affected nutritional status of their mothers. Survival of juveniles during late winter was related to weather conditions during the preceding summer and early winter. We found a compensatory effect of juvenile harvest on subsequent juvenile survival in late winter; 89% of increased juvenile harvest was offset by reduced natural mortality. We also found evidence for a decline in survival of neonates with increasing population size (density dependence). However, the density effect was weak at current population size and recent supplemental feeding rates. Thus, only continued or increased female harvest can maintain this population at current or lower levels if current feeding policies are continued—unless disease prevalence, predator impacts, or other factors substantially alter the historical dynamics. Simulations suggested that harvest rates of mature females must be increased to 15.1% from recent levels of 11.9% to reduce the current population of 15,680 elk (SE = 407) to the target population size of 11,029 set by the Wyoming Game and Fish Department (WGFD). Sensitivity of equilibrium population size at the WGFD target level to harvest rate was very high, requiring regular monitoring and adjustment of harvest to maintain a stable population.

Brucellosis has been eradicated from cattle in the states of Wyoming, Montana, and Idaho, USA. However, free-ranging elk (Cervus elaphus) that use feedgrounds in the Greater Yellowstone Area (GYA) and bison (Bison bison) in Yellowstone and Grand Teton national parks still have high seroprevalence to the disease and have caused loss of brucellosis-free status in Wyoming. Management tools to control or eliminate the disease are limited; however, wildlife vaccination is among the methods currently used by wildlife managers in Wyoming. We conducted a controlled challenge study of single calfhood vaccination. Elk calves, caught in January and February of 1999 and 2000 and acclimated to captivity for 3 weeks, were randomly assigned to control or vaccinate groups. The vaccinate groups received Brucella abortus vaccine strain 19 (S19) by hand-delivered intramuscular injection. Calves were raised to adulthood and bred at either 2.5 or 3.5 years of age for 2000 and 1999 captures, respectively. Eighty-nine (44 controls, 45 vaccinates) pregnant elk entered the challenge portion of the study. We challenged elk at mid-gestation with pathogenic B. abortus strain 2308 by intraconjunctival instillation. Abortion occurred in significantly more (P = 0.002) controls (42; 93%) than vaccinates (32; 71%), and vaccine protected 25% of the vaccinate group. We used Brucella culture of fetus/calf tissues to determine the efficacy of vaccination for preventing infection, and we found that the number of infected fetuses/calves did not differ between controls and vaccinates (P = 0.14). Based on these data, single calfhood vaccination with S19 has low efficacy, will likely have only little to moderate effect on Brucella prevalence in elk, and is unlikely to eradicate the disease in wildlife of the GYA.

We used 35-year and 4-year ungulate exclosures to determine the effects of elk (Cervus elaphus) herbivory on above-ground and below-ground production and soil fertility on the elk winter range in Rocky Mountain National Park (RMNP), Colorado, USA. We used paired grazed and ungrazed plots to evaluate ungulate herbivory effects in short and tall willow (Salix spp.), aspen (Populus spp.), and upland grass/shrub vegetation associations. We measured nitrogen (N) fluxes (litter deposition, fecal and urinary deposition from elk, movements of N by elk, N mineralization, soil N availability, elk consumption rates) within the elk winter, above-ground and below-ground N pools (herbaceous, shrub and root biomass, %N in plants, roots, and soil), and N fluxes on and off the elk winter range (seasonal movement of N by elk). Nitrogen mineralization and soil nitrate (NO₃) pools were reduced in the short willow community (P = 0.07 and 0.10, respectively; n = 4 sites) in grazed plots, but not in the upland grass/shrub community or tall willow sites (P >0.10). Annual growth of willows was reduced by 98% in grazed plots, relative to 35-year exclosures, and 66% relative to 4-year exclosures. Thus, height, canopy size, and litter biomass of willows were reduced, and N yield of willows was 64% less in grazed plots. We evaluated movement of N by elk among 6 major vegetation associations and found that elk grazed more and bedded less in willow vegetation association compared to mixed conifer, mesic meadow, and grassland/shrub associations (P = 0.014, 0.001, and 0.026, respectively), suggesting that elk herbivory and movement led to a net loss of N in the willow vegetation association. Elk spent less total time in willows than mesic meadow association, yet they consumed large amounts of willow plant biomass. We recommend management of elk numbers and elk herbivory that takes into consideration impacts to N process function, as negative effects from current levels of herbivory were observed in ≥1 of 3 vegetation associations studied.

Of the approximately 2,500 California bighorn sheep (Ovis canadensis californiana) in Oregon, USA, the majority descend from a single transplant of 20 animals from British Columbia, Canada, in 1954. Recently, several populations have experienced poor recruitment, raising concerns that populations may be experiencing inbreeding depression resulting from a genetic bottleneck. We sampled 117 animals from 5 populations in Oregon and 1 population in Nevada to determine genetic variability within and among populations. We found that Oregon populations had fewer mean alleles per locus (2.2–2.4), lower heterozygosity (0.28–0.36), and higher inbreeding potential than animals from Nevada (3.8 alleles/locus, H = 0.53). These results now provide the baseline for rigorous ongoing evaluation of changes to allelic variability, inbreeding potential, variation among populations, and their effects on population demographics for Oregon's California bighorn sheep program. We suggest that evaluation of genetic variability in other source and recipient populations should be used to further understand how and when genetic management can be used for bighorn sheep conservation and management.

Use of reported harvests as an index to actual harvest assumes that the proportion of harvest reported is equal for all types of animals and hunters and does not vary spatially or temporally. We modeled reporting rates of white-tailed deer (Odocoileus virginianus) harvest to determine whether they varied by year, deer management unit (DMU), type of deer (antlered or antlerless), or sex. During rifle seasons in Pennsylvania, USA, from 1990 to 2001, reporting rates varied by year, DMU, and type of deer (antlered or antlerless). Harvest estimates of antlered and antlerless deer were precise for both statewide (CV <2.5%) and DMUs (CV < 24%, median CV <5.2%). For DMUs, reported harvests were poor predictors of estimated antlered harvests (median R² = 0.287) but generally acceptable for antlerless harvests (median R² = 0.909). During the 2000 and 2001 hunting seasons, statewide average predicted reporting rates ranged from 36 to 60% and varied by year, hunting season, and type of deer. Average predicted reporting rates also varied by DMU (range = 31.5–57.5%). Applying rifle-season reporting rates to other seasons resulted in overestimating harvest by 26–28%. Variability of reporting rates precluded use of reported harvests as reliable indices of actual harvest. We recommend regular estimation of reporting rates and caution against assuming a constant reporting rate, even in consistent harvest registration systems.

We determined survival rates, causes of mortality, and documented impacts of harvest on ≥1.5-year-old male (hereafter, male) Columbian black-tailed deer (Odocoileus hemionus columbianus) in 2 Washington, USA, game management units (GMUs; Skookumchuck and Snoqualmie) characterized by different hunting-season structures. We monitored 66 males (n = 28 and 38 annually) in Skookumchuck and 58 males (n = 26 and 32 annually) in Snoqualmie, September 1999–September 2001. Annual survival rates were 0.498 (SE = 0.066) in Skookumchuck and 0.519 (SE = 0.067) in Snoqualmie. Survival rates derived from population age structure did not differ from rates derived from radiotelemetry. Harvest was the primary mortality factor for each population, accounting for 67% (SE = 7; Skookumchuck) to 44% (SE = 9; Snoqualmie) of total annual mortality. Annual harvest-specific mortality rates were 0.317 (SE = 0.032) in Skookumchuck and 0.211 (SE = 0.021) in Snoqualmie, likely due to longer hunting seasons and greater hunter effort in Skookumchuck. Following the elimination of a late buck season centered on the rut in Snoqualmie, male harvest declined 56% and annual survival increased 60%, indicating that male harvest was largely additive to other mortality. Our results indicated that harvest was the primary influence on male black-tailed deer populations in Washington, was additive, and that the effect of harvest varied with hunting-season structure and hunter effort. Managers should not assume that harvesting removes a constant proportion of the male population annually, and management models that assume compensatory mortality in adult harvest may result in overharvest of male populations.

Many red deer (Cervus elaphus) inhabit nonnative Scots pine (Pinus sylvestris) and black locust (Robinia pseudoacacia) forested areas with impoverished shrub understory in the Hungarian Plains. Nonnative plants can displace native plant species and alter wildlife habitat use, but few studies have investigated the relationship between the characteristics of these forests and red deer resource use. We investigated whether forest type (main tree species), rate of the main tree species, and age class of nonnative stands determine the typical distribution of certain browse species at the shrub layer. We also examined whether we could predict red deer use of the various forests. We quantified the canopy cover of understory browse and estimated deer diet using microhistological analysis of composite fecal samples collected at 2–4 week intervals between May and November 2000. We also evaluated the habitat use of 3 radiomarked deer in the study area from 1995 to 2001. No significant correlation could be drawn between the characteristics of forest stands and browse at shrub level according to forest types, rate of main tree species, age classes, and canopy cover of the dominant browse species. Red deer consumed mainly browse species (63%) complemented by forbs (31%). The dominant browse species in the diet were black locust (75–71%) and elder (Sambucus nigra; 75–27%). The predominant browse species in the forests were black locust, tree of heaven (Ailanthus altissima), western hackberry (Celtis occidentalis), hawthorn (Crataegus monogyna), elder, and rare browse species categorized as OTHERS. Each browse species formed separate patches—where its cover was significantly higher (range = 45–85%) within the patch than outside (range = 5–9%)—that made up 70% of the lowland forest. Deer occupied habitats containing 1–3 browse clusters. Browse species coverage differed according to individual core areas for deer, but the total browse cover (40%) within the core areas was significantly higher than outside (29%). We concluded that the characteristics of forest stands (type and age) do not predict the behavior of deer in nonnative lowland stands because forest types do not have a characteristic shrub flora. Therefore, neither foraging nor hiding patches were related to overstory characteristics. Thus, a detailed shrub description according to cover and distribution of species is necessary for forest and wildlife management.

Irruptions of ungulate populations have been observed, but little is known of their cause of initiation and termination. We documented an irruption of a naturally colonizing sika deer (Cervus nippon) population on Cape Shiretoko, Shiretoko Peninsula, northeastern Hokkaido, Japan, and we examined limiting factors on population growth. The population increased from 54 deer in 1986 to 592 deer in 1998 (11 to 118 deer/km², respectively) and declined to 177 (35 deer/km²) the following winter of 1999. The intrinsic rate of increase from 1986 to 1998 was 0.19 (95% CI: 0.16 to 0.22). We estimated an annual survival for adult females of 0.92. The ratio of calves to adult females was 76%. We observed a density-correlated reduction in winter food resources. Density-dependent food resources and their interaction with climatic factors were the most important limiting factors for sika deer. The population recovered rapidly following the population crash in 1999 and increased to 512 deer (102 deer/km²) in 2002. We anticipate further increase and a second crash. To confirm whether the population will be regulated naturally and to establish sika deer management policy in Shiretoko National Park, long-term monitoring of the relationship between sika deer and their habitat must be implemented.

Urban development in the Florida Keys, USA, mandates an understanding of how habitat requirements for Florida Key deer (Odocoileus virginianus clavium) interact with vegetation changes caused by development. Our study objectives were to (1) determine Key deer habitat use at different spatial scales, (2) evaluate vegetation changes and identify vegetation types most threatened by development, and (3) provide guidelines to direct land acquisition programs in the future. We identified 6 vegetation types: pineland, hammock, developed, freshwater marsh, buttonwood, and mangrove. Key deer (n = 180; 84 F, 96 M) preferred upland vegetation types (>1 m above mean sea level; pineland, hammock, developed) and avoided tidal or lower-elevation areas (<1 m above mean sea level; freshwater marsh, buttonwood, mangrove). Analyses of Geographic Information System (GIS) coverages suggested that historical development impacted near-shore habitats while recent trends pose a greater risk to upland areas (pineland, hammock). Because uplands are preferred by Key deer, conservation measures that include land acquisition and habitat protection of these areas may be needed.

The endangered Florida Key deer (Odocoileus virginianus clavium) is endemic to the Florida Keys, Florida, USA, with Big Pine Key (BPK) supporting most (approx 60%) of the population. Habitat loss and fragmentation have altered the amount of available habitat, creating areas of varying suitability; north BPK (NBPK) is believed to contain more optimal habitat than south BPK (SBPK), which is more developed and fragmented. We evaluated the source–sink dynamics of Key deer using a sex- and stage-structured, stochastic matrix model. Model results indicated that the NBPK population of Key deer was increasing (λ = 1.02), whereas the SBPK population was decreasing (λ = 0.87). Without dispersal from the north, the SBPK population has a 97% probability of falling below 25 individuals (quasi-extinction threshold) in the next 20 years. The higher risk to Key deer in SBPK can be explained by relative habitat-quality differences between the 2 areas. House density, amount of roads, number of fences, and amount of development were all greater in SBPK. Collectively, study results indicate that SBPK can be described as an ecological sink with a nonviable population supplemented by deer dispersal from NBPK (source). Care should be taken to preserve the source population and its habitat. Thus, we propose limiting future development in NBPK (high-quality source habitat). The US 1 highway corridor project has the potential to decrease Key deer mortality due to vehicle collisions, and we recommend that future management goals continue to address mortality factors on SBPK (low-quality sink habitat).

In sub-Saharan Africa, the widespread practice of corralling livestock overnight in thorn-scrub “bomas” creates nutrient-enriched patches within rangelands that can subsequently support unique plant communities for decades to centuries after boma abandonment. These nutrient-rich patches (glades) may be preferentially used by native ungulates that coexist with livestock. To evaluate the potential link between cattle management via bomas and habitat for impala (Aepyceros melampus), I examined seasonal patterns of habitat selection by impala and landscape variation in grass nutrient content on a commercial cattle ranch in central Laikipia, Kenya. Studies using automated, infrared camera monitors showed that impala selected nutrient-rich glades 2.6 times more frequently than surrounding Acacia bushland habitat during dry seasons, and 9.6 times more frequently during wet seasons. Significantly greater impala presence in glade versus bushland habitat during dry seasons suggests that impala presence may be related to reduced predation risk in shrub-free glades. The large, significant increase in impala presence in glades from dry to wet seasons suggests that impala distribution also is linked to the availability of nutrient-rich forage. In particular, grass nutrient analyses showed that wet-season phosphorus (P) concentrations in grasses throughout the bushland landscape (x̄ = 2,125 mg P/kg dry matter, varying from 1,789 to 2,922 mg P/kg across topographic positions and from 1,508 to 3,215 mg P/kg among grass species) were below recommended levels for pregnant and lactating ruminants, while mean P concentrations in glade grasses (x̄ ± SE = 5,346 ± 2.92 mg P/kg) exceeded recommended levels. Results suggest that management to increase the relocation rate and distribution of current cattle bomas can have a positive, long-term effect on the local distribution and abundance of impala.

Guanacos (Lama guanicoe) are the largest native Artiodactyl in South America and the most widely distributed. In arid Patagonia, densities are low and negatively related to domestic sheep numbers in space and time consistent with interspecific competition theory. Although guanacos and domestic sheep have been described as intermediate feeders sharing food resources, no studies have been conducted to compare their diets in sympatric conditions and explore whether the potential exists for direct interspecific competition. We assessed the diet of both species across 9 different sites and 2 seasons by microhistological analysis of fecal samples. We found that (1) guanacos and sheep are generalist herbivores feeding on a wide range of plant species; (2) both are intermediate feeders able to include both monocotyledoneous and dicotyledoneous plants in their diet; (3) both are able to change their diets seasonally; and (4) food niche overlap is high, particularly in summer when food resources are more scarce than in spring. We conclude that the potential for competition between guanacos and sheep is high and could have played a major role in the demise of guanacos. Consequently, current management practices focused on maximizing sheep numbers are not compatible with the recovery of guanaco populations.

Since 1980, populations of wild boar (Sus scrofa) have increased over the species' entire European range. This increase has led to conflicts because wild boars cause crop damage amounting to several million U.S. dollars every year. Wildlife management agencies promote and financially support 3 major methods to reduce the loss: (1) intensive harvest, (2) supplemental feeding in forests to bait animals for easier shooting and to distract them from agricultural fields, and (3) building electrical fences around crops at risk. Our objective was to investigate how effective these methods were in reducing field damage by wild boars. Based on data from 44 hunting territories in the Canton Thurgau, Switzerland, we related damage frequency to harvest success, supplemental feeding, and fencing effort by means of 2 multiple regression analyses. The analysis of mean damage frequency among territories (averaged over 3 years) and changes in damage frequency within territories from 1994 to 1996 showed that only hunting reduced damage by wild boars. Because our results question the effectiveness of wild boar management practices and wild boar populations and damage are increasing throughout Europe, we suggest that control efforts and funds be reconsidered. Because only hunting seems to clearly reduce wild boar damage, we suggest more emphasis be put on the development and introduction of new harvest models among local hunting teams.

Biologists have monitored black bear (Ursus americanus) populations using annual Lincoln-Petersen (L-P) estimates of population size derived from the fraction of marked bears recovered in the harvest. Although spatial, temporal, and demographic factors have been linked to variation in harvest rates of black bears, the effect of this heterogeneity on mark–recapture population estimates has not been evaluated. Failure to incorporate heterogeneity in harvest rates can result in biased population estimates and poor precision, which may lead to inappropriate management decisions. We used records of 6,982 bears captured during 1983–2001 in Pennsylvania, USA, to estimate the probability of harvest related to spatiotemporal, environmental, and demographic characteristics associated with individual bears. Harvest rates varied according to sex, age class, hunter density, and snow cover. In addition, harvest rates varied temporally (by year and month of capture) and spatially across Pennsylvania. Model selection based on Akaike's Information Criterion (AIC) supported a more complex harvest model based on a Horvitz-Thompson (H-T) estimator than the simpler model implicitly assumed by a series of annual L-P estimates. The H-T estimates of population size, which incorporated heterogeneity in harvest rates, were consistently lower than the annual L-P estimates because the H-T estimates accounted for mortality that occurred prior to the hunting season in addition to other sources of harvest heterogeneity. However, significant heterogeneity among breeding-age females could not be incorporated because we did not know the reproductive status (pregnant or with cubs) of each tagged and harvested female bear. Additional predictive variables of harvest rates of breeding-age females could further improve our model; however, an extension of our model that incorporates data from tagged cohorts may be an alternative means to improve the accuracy and precision of population estimates.

We used microsatellite marker data taken from Scandinavian brown bear (Ursus arctos) tissue samples collected by hunters and biologists to estimate population genetic parameters important for bear management. Specifically, we show evidence of a small effective population size (N̂_e = 44.8; 95% CI: 30.9 to 73.2) and low rates of immigration (m̂ = 0.01; 95% CI: 0.00 to 0.05) into the brown bear population along the southern edge of their range in Scandinavia. The ratio of genetic effective size to population size is approximately 0.06–0.14, which falls within the range of values found in previous studies of brown bears. The large confidence intervals around the immigration estimate reflect considerable uncertainty. Nonetheless, these values deserve attention because they are near thresholds of short-term management concern and worthy of long-term monitoring. If the genetic effective size remains this small and immigration remains low, then this population could be subject to the loss of fitness as a consequence of inbreeding effects.

Wildlife ecologists often use the Kaplan-Meier procedure or Cox proportional hazards model to estimate survival rates, distributions, and magnitude of risk factors. The Andersen–Gill formulation (A–G) of the Cox proportional hazards model has seen limited application to mark–resight data but has a number of advantages, including the ability to accommodate left-censored data, time-varying covariates, multiple events, and discontinuous intervals of risks. We introduce the A–G model including structure of data, interpretation of results, and assessment of assumptions. We then apply the model to 22 years of radiotelemetry data for grizzly bears (Ursus arctos) of the Greater Yellowstone Grizzly Bear Recovery Zone in Montana, Idaho, and Wyoming, USA. We used Akaike's Information Criterion (AIC_c) and multi-model inference to assess a number of potentially useful predictive models relative to explanatory covariates for demography, human disturbance, and habitat. Using the most parsimonious models, we generated risk ratios, hypothetical survival curves, and a map of the spatial distribution of high-risk areas across the recovery zone. Our results were in agreement with past studies of mortality factors for Yellowstone grizzly bears. Holding other covariates constant, mortality was highest for bears that were subjected to repeated management actions and inhabited areas with high road densities outside Yellowstone National Park. Hazard models developed with covariates descriptive of foraging habitats were not the most parsimonious, but they suggested that high-elevation areas offered lower risks of mortality when compared to agricultural areas.

Minimizing human-caused mortality by providing alternative solutions to human–bear conflicts is important for the conservation and management of Asiatic black bear (Ursus thibetanus) populations. We found a positive correlation (P < 0.05) between the number of nuisance bears killed and a beechnut (Fagus crenata) crop failure index in 5 of 7 zones in the Tohoku region of Japan. In areas where bears are highly dependent on beechnuts as food in autumn, we suggest that agencies could issue warnings about nuisance bears in years of crop failure using the current monitoring network of beechnut production. This system could be a valuable method not only to reduce human–bear conflicts but also to enhance public consciousness of bear conservation and management.

Studies assessing the potential negative consequences of radiocollars on endangered mammals are few. No such studies have been conducted on giant panda (Ailuropoda melanoleuca), an endangered species potentially sensitive to invasive monitoring technologies and handling. Lack of knowledge about the effects of radiocollars and concern for the well-being of radiocollared pandas led to a moratorium on radiocollaring the species in the wild in 1995. To assess the potential effect of radiocollars on the behavior of giant pandas, 4 captive giant pandas (2 male, 2 female) were immobilized and fitted with radiocollars during February and March 2000, just prior to the mating season. We evaluated potential behavioral and endocrine indices of stress daily for 2 weeks before and after immobilization and attachment of radiocollars. We found no significant change in stereotypic behaviors, activity levels, or cortisol levels for any of the 4 individuals. Both adult radiocollared pandas mated successfully. Our results suggest that any potential short-term negative effects from radiocollaring giant pandas are negligible, and with proper planning and use, radiotelemetry can be safely utilized in the study of free-ranging giant pandas.

We studied the effects of mountain lion (Puma concolor) predation on 2 translocated populations of bighorn sheep (Ovis canadensis) in New Mexico, USA. During 1993, 32 Rocky Mountain bighorn sheep (O. c. canadensis) were translocated to Wheeler Peak Wilderness Area in northern New Mexico, and during 1992–1993, 31 desert bighorn sheep (O. c. mexicana) were translocated to Sierra Ladron in central New Mexico. We monitored both populations from release through 2000 using fixed-wing aircraft and ground and/or helicopter surveys. We determined cause of mortality for radiomarked individuals (n = 26) and calculated survival rates, cause-specific mortality rates, exponential growth rates, and lamb:ewe ratios. The post-lambing population estimates in 2000 were 180 in Wheeler Peak and 21 in Sierra Ladron. Annual adult survival was higher (P < 0.005) in the Wheeler Peak population (0.955) than in the Sierra Ladron population (0.784). Annual lamb:ewe ratios also were higher (P < 0.001) in the Wheeler Peak population (66.7 vs. 29.8). Mean annual exponential growth rate (r) in the Wheeler Peak population was 0.25 compared to −0.01 for the Sierra Ladron population. Predation by mountain lions was the primary proximate cause (75%) of 16 known-cause mortalities of radiomarked bighorn sheep in the Sierra Ladron population, while we did not document any predation in Wheeler Peak. The annual cause-specific mortality rates due to mountain lion predation in Sierra Ladron were 0.13 for males, 0.09 for females, and 0.11 for all adult bighorn sheep. Mountain lion predation may have limited the Sierra Ladron bighorn sheep population and could be imposing a destabilizing inverse density-dependent mortality. Mountain lions preyed on domestic cattle in the Sierra Ladron area and throughout desert bighorn sheep habitat in New Mexico; we therefore hypothesize that cattle “subsidized” the diets of mountain lions (i.e., reduced or eliminated natural starvation). The ultimate cause of mortality for these desert bighorn sheep may be related to subsidized mountain lion populations that do not appear to decline following native ungulate population decreases. In addition, the encroachment of woody vegetation may increase the hunting success of ambush predators like mountain lions. High mountain lion predation may require mitigation for the successful restoration of bighorn sheep.

Coyotes (Canis latrans) are now ubiquitous throughout most of the eastern United States; however, little information exists on how they are able to exploit and thrive in fragmented landscapes. We investigated home ranges, movements, and scale-dependent resource selection of coyotes along a gradient (suburban/exurban/rural) of anthropogenic disturbance. Home-range sizes varied along a suburban-to-rural gradient and were inversely correlated to urbanization (R² = 0.79, P < 0.001). Habitat composition and coyote use of 95% (home range) and 50% (core area) contours were nonrandom. Coyotes used corridor habitat extensively and avoided urban and crop-field habitats. Forested habitat was used extensively for diurnal cover. Rural coyotes traveled greater distances at faster rates than did suburban/exurban coyotes. Diel activity patterns were similar along the gradient, suggesting that coyotes responded similarly to differing levels and types of human activity. Coyotes appeared to assess habitat quality at the landscape scale and exploited small, disjunct resource patches present in developed landscapes. We believe that the availability of foraging habitat and travel corridors is critical to movement of coyotes in areas of high human activity.

Baiting red foxes (Vulpes vulpes) is an established method of vaccinating foxes against rabies in rural environments. Furthermore, anthelmintic baiting has been demonstrated to reduce the prevalence of the zoonotic tapeworm Echinococcus multilocularis in foxes. The recent invasion of foxes into urban areas on continental Europe represents a considerable health risk that calls for the evaluation of baiting strategies adapted to the urban environment. We investigated bait uptake by urban foxes using camera traps in Zurich, Switzerland. Baits with and without the anthelmintic praziquantel were placed in several arrangements (exposed, covered, buried), at different locations (fox dens, compost heaps, fox tracks) and in different seasons (early summer, summer, winter). Ninety-one of 252 baits (36%) disappeared within 3 days. Most of the baits consumed near cameras were consumed by foxes (44 of 91). The remaining baits were consumed by hedgehogs (Erinaceus europaeus), snails (Arion sp.), dogs, rodents (Apodemus sp.), and unidentified animals. Bait uptake by foxes was significantly higher during summer than winter (P = 0.022), and foxes accepted baits most frequently at fox dens during early summer (52.8%). Burying baits reduced bait removal by species other than foxes (P < 0.01). For rabies control in urban areas, avoiding contact of nontarget species with the rabies vaccine is particularly important. Greater selection of the fox population can be achieved by distributing baits in winter, burying baits, and choosing sites that are less accessible to non-target species. However, with anthelmintic treatment, uptake by nontarget species is of lesser importance; hence, the effort to bury the bait is unnecessary.

We compared the reproductive biology, dispersal, and subadult survival of bald eagles (Haliaeetus leucocephalus) from nest sites in suburban and rural landscapes in west-central Florida, USA, from 1997 to 2001. We documented the reproductive outcome of randomly selected suburban (n = 60) and rural (n = 60) bald eagle nest attempts. We also used satellite tracking packages on randomly selected rural (n = 35) and suburban (n = 35) bald eagle fledglings. Nest-site occupancy varied among years (range = 75.0–100.0%), but averaged 90% for nests in both land-use categories. The overall mean nesting start date was similar for both groups (suburban = 11 Dec, rural = 13 Dec). Bald eagles occupying nest sites in both land-use categories raised an average of 1.3 young to 8 weeks-of-age, and pairs that fledged ≥1 young raised an average of 1.7 young to 8 weeks-of-age. Most bald eagle fledglings from our study area migrated northward, some as far as Newfoundland, Canada. The core summering area was the Chesapeake Bay and the coastal plain of North Carolina, USA. Successful fledglings started northward migration earlier on average at rural than at suburban nest sites (124 vs. 132 days-of-age). Survival of both groups was similar until dispersal (approx 91%); however, during the first northward migration, mortality of suburban fledglings increased disproportionately. One year after fledging, survival of rural fledglings was 89% compared to 65–72% for suburban fledglings. Survival of the 2 groups was similar (84–90%) thereafter. Suburban bald eagles died more often from anthropogenic factors (primarily electrocution and vehicle collision) than rural bald eagles, though most of these deaths occurred in rural areas after dispersal from natal areas. We suggest that suburban bald eagle fledglings were more acclimated to dangerous anthropogenic landscape features than rural eagles, and as such did not regard them with the same degree of caution. Despite the difference in first-year mortality, population models suggest that both groups are experiencing positive population growth rates.

We constructed a linear, discrete-time, 3-age-class population model for peregrine falcons (Falco peregrinus anatum) in Colorado, USA, from estimates of survival and reproduction derived from banded birds (1973–2001) and monitored nests (1989–2001). Survival estimates were 0.544 ± 0.077 for 0–1-year-old birds, 0.670 ± 0.098 for 1–2 year olds, and 0.800 ± 0.054 for birds >2 years of age. Average young produced per pair was 1.660 (SE = 0.044), but we found considerable variation across years (minimum = 1.388 ± 0.155 in 1995; maximum = 2.122 ± 0.139 in 2000). The population model constructed from these estimates predicted an annual rate of population increase of 1.029 if females were to reproduce at 3 years of age, and 1.080 if they first reproduced at 2 years of age. With appropriate estimates of population parameters, our model provides a method for managers to estimate impacts of falconry harvest upon wild peregrine stocks.

Northern spotted owls (Strix occidentalis caurina) are known to be associated with late-successional forests in the Pacific Northwest of the United States, but the effects of habitat on their demographic performance are relatively unknown. We developed statistical models relating owl survival and productivity to forest cover types within the Roseburg Study Area in the Oregon Coast Range of Oregon, USA. We further combined these demographic parameters using a Leslie-type matrix to obtain an estimate of habitat fitness potential for each owl territory (n = 94). We used mark–recapture methods to develop models for survival and linear mixed models for productivity. We measured forest composition and landscape patterns at 3 landscape scales centered on nest and activity sites within owl territories using an aerial photo-based map and a Geographic Information System (GIS). We also considered additional covariates such as age, sex, and presence of barred owls (Strix varia), and seasonal climate variables (temperature and precipitation) in our models. We used Akaike's Information Criterion (AIC) to rank and compare models. Survival had a quadratic relationship with the amount of late- and mid-seral forests within 1,500 m of nesting centers. Survival also was influenced by the amount of precipitation during the nesting season. Only 16% of the variability in survival was accounted for by our best model, but 85% of this was due to the habitat variable. Reproductive rates fluctuated biennially and were positively related to the amount of edge between late- and mid-seral forests and other habitat classes. Reproductive rates also were influenced by parent age, amount of precipitation during nesting season, and presence of barred owls. Our best model accounted for 84% of the variability in productivity, but only 3% of that was due to the habitat variable. Estimates of habitat fitness potential (which may range from 0 to infinity) for the 94 territories ranged from 0.74 to 1.15 (x̄ = 1.05, SE = 0.07). All but 1 territory had 95% confidence intervals overlapping 1.0, indicating a potentially stable population based on habitat pattern. Our results seem to indicate that while mid- and late-seral forests are important to owls, a mixture of these forest types with younger forest and nonforest may be best for owl survival and reproduction. Our results are consistent with those of researchers in northern California, USA, who used similar methods in their analyses. However, we believe that given the low variability in survival and productivity attributed to habitat, further study is needed to confirm our conclusions before they can be used to guide forest management actions for spotted owls.

The recovery plan for the Mexican spotted owl (Strix occidentalis lucida) recommended protection of owl nesting and roosting habitat. Descriptions of microhabitat (≤0.04 ha) characteristics associated with suitable nesting sites have been limited for the area of pine–oak forest occupied by this species in Arizona, USA. Therefore, we studied Mexican spotted owl habitat on a 585-km² study area on the Coconino Plateau near Flagstaff, Arizona. Mexican spotted owls nested primarily in mature (≥45.7-cm diameter at breast height [dbh]) Gambel oak (Quercus gambelii; 40%) and ponderosa pine (Pinus ponderosa; 37%) trees. We examined a plausible set of a priori models using both standard logistic regression and matched pairs logistic regression under a model-selection framework. Our results suggested that spotted owl nest and roost sites were located on steeper slopes with greater percent canopy closure and greater mature and old-growth tree basal area than random sites. The presence of mature and old-growth hardwood trees was an important factor distinguishing spotted owl nest sites from all other plot types. We recommend management for mature and old-growth trees, and for large (≥45.7-cm dbh) oak trees in particular. In addition, due to the importance of oaks as a resource for nest and roost sites, we recommend a ban on fuelwood harvest of oaks. We present, for the first time, physical characteristics of Mexican spotted owl nest structures, which will aid resource managers in identifying potential nest sites in the field.

Wildlife practitioners concerned with midcontinent mallard (Anas platyrhynchos) management in the United States have instituted a system of adaptive harvest management (AHM) as an objective format for setting harvest regulations. Under the AHM paradigm, predictions from a set of models that reflect key uncertainties about processes underlying population dynamics are used in coordination with optimization software to determine an optimal set of harvest decisions. Managers use comparisons of the predictive abilities of these models to gauge the relative truth of different hypotheses about density-dependent recruitment and survival, with better-predicting models giving more weight to the determination of harvest regulations. We tested the effectiveness of this strategy by examining convergence rates of “predictor” models when the true model for population dynamics was known a priori. We generated time series for cases when the a priori model was 1 of the predictor models as well as for several cases when the a priori model was not in the model set. We further examined the addition of different levels of uncertainty into the variance structure of predictor models, reflecting different levels of confidence about estimated parameters. We showed that in certain situations, the model-selection process favors a predictor model that incorporates the hypotheses of additive harvest mortality and weakly density-dependent recruitment, even when the model is not used to generate data. Higher levels of predictor model variance led to decreased rates of convergence to the model that generated the data, but model weight trajectories were in general more stable. We suggest that predictive models should incorporate all sources of uncertainty about estimated parameters, that the variance structure should be similar for all predictor models, and that models with different functional forms for population dynamics should be considered for inclusion in predictor model sets. All of these suggestions should help lower the probability of erroneous learning in mallard AHM and adaptive management in general.

The North American continental population of lesser scaup (Aythya affinis) has been declining since the mid-1980s. Seasonal survival estimates may provide insights about the ecological basis for this decline, but such data are not available. We estimated post-harvest winter survival of lesser scaup in east-central Florida, USA, where 62% of the Atlantic Flyway population winters. The Kaplan-Meier survival estimate from 11 January to 14 March 2002 was 0.95 ± 0.04 (SE) for females and 0.90 ± 0.09 for males. These estimates were not different (P = 0.64), and pooled survival was 0.93 ± 0.04. Temporary emigration (movement out of and return to the study area) was exhibited by 25% of the birds during survey periods, but absences were short and were believed to have had little effect on precision of survival estimates. Our findings suggested that natural mortality at Merritt Island National Wildlife Refuge (MINWR) and surrounding estuarine areas was relatively low. Our results also indicate that habitat quality in this portion of east-central Florida was sufficient to meet overwintering requirements and likely contributed to the reported survival rates. Estimating survival during other stages of the annual cycle, as well as an overall winter estimate reflecting harvest mortality, is necessary to determine whether low survival rates are responsible for continental population declines.

The ratio of juveniles to adults in the fall harvest is a common index of production for Galliformes. The percentage of juvenile birds in the harvest has been shown to decline as the hunting season progressed for many galliforms, resulting in a biased index of production. Therefore, we used wing samples of plains sharp-tailed grouse (Tympanuchus phasianellus jamesi) and greater prairie-chickens (T. cupido pinnatus) from 4 public land areas in the Nebraska Sandhills, Nebraska, USA, to assess the potential for bias in harvest-age ratios across time. We hypothesized that the ratio of juveniles to adults in the harvest could change over time if susceptibility to harvest and/or fall survival were different between the juvenile and adult prairie grouse (Tympanuchus spp.) in the Nebraska populations. We found no change in the harvest-age ratio over time in either the sharp-tailed grouse or greater prairie-chicken data. Our findings were consistent with the published literature on harvest-age rates for sharp-tailed grouse but inconsistent with the greater prairie-chicken literature. Therefore, we maintain that analysis of the harvest data for bias due to a changing harvest-age ratio as the hunting season progresses is an essential adjunct to subsequent analysis or comparisons of production indices based on harvest-age ratios. In addition, limitations of harvest-age ratios must be known and care must be taken to minimize other potential biases before using harvest-age ratios as an index to production.

Scientific management of quail harvest at the state level must be based on a clear understanding of the effects of hunting regulations on hunters and populations. Therefore, we assessed how reduction in bag limits would affect hunter opportunity and harvest rates of northern bobwhites (Colinus virginianus) in Oklahoma, USA, using harvest data from questionnaire surveys. Reductions in bag limits were regressive because reductions had relatively less effect on hunting opportunity and harvest rate at low populations than at high populations. Based on data primarily from Oklahoma and Missouri, we found that the negative binomial distribution described the probability of an integer bag (0, 1, 2, 3, … birds) if the mean and variance of daily bag were known. The negative binomial distribution provides a general method of assessing the effects of bag-limit reduction on hunting opportunity and harvest rates. The skill of the average hunter apparently declined as the statewide bobwhite population increased. Although hunting was self-regulatory in that the number of hunters declined as the bobwhite population declined, it was not self-regulatory when adjusted for the relative skill of hunters at low and high populations. We argue that fixed, relatively low bag limits established as a risk-aversive strategy for low populations of bobwhites may not necessarily have large impact on hunting opportunity with high populations.

We derived consequences (realizations of hunter efficiency, relative harvest rates) of fixed, liberal quail (northern bobwhite [Colinus virginianus], Gambel's quail [Callipepla gambelii], and scaled quail [C. squamata]) harvest regulations applied at large scales from time series on quail abundance, total harvest, and hunter participation. Data came from Kansas (1966–2001), Missouri (1983–2001), Oklahoma (1990–2001), north and south Texas (1986–2001), and Arizona (1982–1999), USA, where harvest regulations were liberal (season length 2.5–4 months, daily bag limit 8–15 birds) during the periods of record. For all study regions, hunter-days were expressible as a linear function of quail abundance, and total harvest was expressible as a linear function of hunter-days. These results implied that hunter efficiency (harvest/hunter-day/index bird) declined monotonically and curvilinearly as quail populations increased. Likewise, relative harvest rate declined monotonically and curvilinearly as abundance increased, which implied that harvest was not self-limiting; however, the rate of decline generally was low because harvest rate was the product of an increasing (hunter-days) and a decreasing function (hunter efficiency) of quail abundance. Under fixed, liberal regulations, variations in quail abundance seem to govern harvest rates at the state or regional level; the regulations per se probably are biologically inconsequential.

Bachman's sparrow (Aimophila aestivalis), a near endemic songbird of the longleaf pine (Pinus palustris) ecosystem, is known to respond positively to prescribed fires. The influence of season (growing vs. dormant) and frequency (1 to ≥4 yr since burning) of fire on density of Bachman's sparrows, however, is poorly understood. We examined effects of fire on density of Bachman's sparrows in longleaf pine forests at the Conecuh National Forest, Alabama, and Blackwater River State Forest, Florida, USA. Density of Bachman's sparrows was greater the first 3 years after burning than ≥4 years after burning, and season of burning had little effect on the density of Bachman's sparrows. Percent coverage by grass had a greater influence on density of Bachman's sparrows than either season or frequency of burning. Percent canopy cover had a strong negative effect on coverage of grass but had a weaker effect on grass at stands burned frequently during the growing season. Growing-season fires (Apr–Sep) did not adversely affect density of Bachman's sparrows. Results from our study suggest that management and restoration of longleaf pine communities probably can be accomplished best by burning on a 2–3-year rotation during the growing season, when most fires historically occurred. Suppression of fire, or burning at intervals >4–5 years, will greatly reduce or eliminate habitat required by Bachman's sparrows.

Flight initiation distance (FID), or the distance between a prey animal and an approaching intruder when the prey initiates its escape, is an important factor in wildlife management. We conducted a study on individually identified yellow-bellied marmots (Marmota flaviventris) to test 3 key assumptions of FID research: (1) differences in individual responses are small enough so as not to confound results; (2) pseudoreplication may bias results; and (3) habituation and sensitization can be studied without knowledge of individuals. We found that individual identity was not a significant predictor of FID. Furthermore, a moderate degree of pseudoreplication did not significantly affect the results of most analyses. However, individuals differed greatly in their rates of habituation, such that habituation was apparent only when individual identity was known and could not be detected without knowledge of individuals. If our marmot results can be generalized to other species, they suggest that researchers need not be concerned about individual identity when studying variables largely dependent on environmental factors, but that identification of individuals is important for studies of properties of individuals, such as habituation.

For the sustainable management of small mammals, fertility control may be used in the future. Little is known about what proportions of females need to be sterilized to achieve an impact on population size and what compensatory processes may act on the population level. We tested the impact of surgical sterilization of zero, 25, 50, and 75% of females on the population dynamics and demography of enclosed populations of ricefield rats (Rattus argentiventer) and damage to rice crop. Sterilizing 50% of female founders (6 of 12) decreased population size at the end of the breeding season by about 50%. We used a simulation model, based on the breeding biology of the ricefield rat in the field and in the control enclosures, to generate the expected dynamics of the enclosure populations. The results suggested that compensation occurred in the enclosures where 75% of female founders (9 of 12) had been sterilized. We detected a slight tendency for 50% higher numbers of recent uterine scars in fertile founder females in the 50% and 75% treatments versus 25% treatments and controls (P = 0.198). The primary demographic mechanism for compensation was higher survival of young rats in enclosures where 75% of females were sterilized. However, compensation only partially offset the decrease in population size. We found no conclusive evidence that the reproductive output of F₁ generation females was higher when large proportions of female founders were sterilized. Early in the breeding season, the per capita damage to rice plants in populations without sterilized ricefield rats was increased. Our results suggest that the sterilization of >50% of females in ricefield rat populations can reduce rat population growth and rat damage to rice crops.

Fertility control is used for the management of overabundant species. If sterilized individuals abandon their territories, fertile immigrants may invade and compromise fertility control. In southeast Asia, ricefield rats (Rattus argentiventer) can cause significant pre-harvest damage to lowland irrigated rice fields and may be a prime target for the use of fertility control. However, little is known about the behavioral response of ricefield rats to sterilization. We tested the effects of surgical and hormonal sterilization on movement patterns of female ricefield rats in rice fields in West Java, Indonesia. We found that surgically sterilized rats had the largest home ranges (1.8 ± 0.1 ha), about twice the size of home ranges of hormonally sterilized rats and fertile rats. Hormonally sterilized rats tended to lose their territories—indicated by a high rate of burrow relocation—although hormonally sterilized, surgically sterilized, and fertile rats did not leave the ricefield system. We found no difference in survival rate and preference for refuge habitats between sterilized and fertile rats. Although changes in movement patterns after sterilization occurred, these changes are unlikely to affect the success of fertility control in ricefield rats negatively because sterilized rats remained in the ricefield system throughout the breeding period.

We investigated variation of incidentally captured turtle mortality in response to environmental factors and passive fishing techniques. We used Long Term Resource Monitoring Program (LTRMP) data collected from 1996 to 2001 in the unimpounded upper Mississippi River (UMR) adjacent to Missouri and Illinois, USA. We used a principle components analysis (PCA) and a stepwise discriminant function analysis to identify factors correlated with mortality of captured turtles. Furthermore, we were interested in what percentage of turtles died from passive fishing techniques and what technique(s) caused the most turtle mortality. The main factors influencing captured turtle mortality were water temperature and depth at net deployment. Fyke nets captured the most turtles and caused the most turtle mortality. Almost 90% of mortalities occurred in offshore aquatic areas (i.e., side channel or tributary). Our results provide information on causes of turtle mortality (as bycatch) in a riverine system and implications for river turtle conservation by suggesting management strategies to reduce turtle bycatch and decrease mortality of captured turtles.

Identifying the cues used by spotted salamanders (Ambystoma maculatum) to select forested habitat may provide insight into their habitat requirements and preferences. Environmental factors, such as temperature and moisture, are consistently important factors in explaining the magnitude and timing of annual breeding migrations and are important characteristics of quality terrestrial habitat. These factors, however, may not be used to select terrestrial habitat because microclimate gradients are minimal when salamanders are migrating. To test whether substrates provide cues for habitat selection, we presented juvenile and adult spotted salamanders with a choice between substrates collected from forest or grassland. Further, we presented adults with a choice between litter and a combination of soil and litter collected from forest or grassland. We recorded substrate selection initially and at 3-min intervals for 60 min. Salamanders tended to select the forest substrate more than the grassland substrate in all 4 experiments. Overall, juveniles (88%) selected forest soil more than adults (70%). Adults initially selected forest soil (80%), but the response declined with time. However, when we presented soil and litter in combination, salamanders hid under the litter, and the selection of forest substrate (70%) did not decline with time. The establishment of cues influencing habitat selection provides mechanistic information that may be used to predict habitat selection under scenarios of anthropogenic habitat alteration. Our results suggest that substrate characteristics may influence the presence of salamanders within various habitat types.