[Show abstract][Hide abstract] ABSTRACT: Spatial capture-recapture (SCR) models have advanced our ability to estimate population density for wide ranging animals by explicitly incorporating individual movement. Though these models are more robust to various spatial sampling designs, few studies have empirically tested different large-scale trap configurations using SCR models. We investigated how extent of trap coverage and trap spacing affects precision and accuracy of SCR parameters, implementing models using the R package secr. We tested two trapping scenarios, one spatially extensive and one intensive, using black bear (Ursus americanus) DNA data from hair snare arrays in south-central Missouri, USA. We also examined the influence that adding a second, lower barbed-wire strand to snares had on quantity and spatial distribution of detections. We simulated trapping data to test bias in density estimates of each configuration under a range of density and detection parameter values. Field data showed that using multiple arrays with intensive snare coverage produced more detections of more individuals than extensive coverage. Consequently, density and detection parameters were more precise for the intensive design. Density was estimated as 1.7 bears per 100 km2 and was 5.5 times greater than that under extensive sampling. Abundance was 279 (95% CI = 193-406) bears in the 16,812 km2 study area. Excluding detections from the lower strand resulted in the loss of 35 detections, 14 unique bears, and the largest recorded movement between snares. All simulations showed low bias for density under both configurations. Results demonstrated that in low density populations with non-uniform distribution of population density, optimizing the tradeoff among snare spacing, coverage, and sample size is of critical importance to estimating parameters with high precision and accuracy. With limited resources, allocating available traps to multiple arrays with intensive trap spacing increased the amount of information needed to inform parameters with high precision.
PLoS ONE 10/2014; 9(10):e111257. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Individual variation and fitness are cornerstones of evolution by natural selection. The niche variation hypothesis (NVH) posits that when interspecific competition is relaxed, intraspecific competition should drive niche expansion by selection favoring use of novel resources and that among-individual variation should confer a selective advantage. Population-level niche expansion could be achieved by all individuals using all available resources, or by each individual using a unique combination of resources, thereby increasing among-individual dietary niche variation. Although individual variation can lead to species-level evolutionary and ecological change, observed variation does not ensure a beneficial outcome. We used carbon and nitrogen stable isotope analysis of claw keratin and a Bayesian stable isotope mixing model to estimate the summer (July–September) assimilated diet of individual female black Ursus americanus and brown U. arctos bears. We quantified variation in dietary niche in both populations, and assessed diet relative to percentage body fat. We hypothesized that if the NVH held, percentage body fat would be similar for individuals of the same species across much of the dietary range of observed proportional salmon contributions to individual bear diets. Although we found greater differences in dietary niches between than within species, we observed greater among-individual dietary variation in the brown bear population. Moreover, we found that within each species individual female bears achieved similar ranges of percentage body fat at various levels of salmon in the diet. Our results provide support for the NVH. Linking individual dietary niches to measures of physiological condition related to fitness can offer new insights into eco-evolutionary processes related to food resource use.
[Show abstract][Hide abstract] ABSTRACT: Wildlife incidents with aircraft cost the United States (U.S.) civil aviation industry >US$1.4 billion in estimated damages and loss of revenue from 1990 to 2009. Although terrestrial mammals represented only 2.3 % of wildlife incidents, damage to aircraft occurred in 59 % of mammal incidents. We examined mammal incidents (excluding bats) at all airports in the Federal Aviation Administration (FAA) National Wildlife Strike Database from 1990 to 2010 to characterize these incidents by airport type: Part-139 certified (certificated) and general aviation (GA). We also calculated relative hazard scores for species most frequently involved in incidents. We found certificated airports had more than twice as many incidents as GA airports. Incidents were most frequent in October (n = 215 of 1,764 total) at certificated airports and November (n = 111 of 741 total) at GA airports. Most (63.2 %) incidents at all airports (n = 1,523) occurred at night but the greatest incident rate occurred at dusk (177.3 incidents/hr). More incidents with damage (n = 1,594) occurred at GA airports (38.6 %) than certificated airports (19.0 %). Artiodactyla (even-toed ungulates) incidents incurred greatest (92.4 %) damage costs (n = 326; US$51.8 million) overall and mule deer (Odocoileus hemionus) was the most hazardous species. Overall, relative hazard score increased with increasing log body mass. Frequency of incidents was influenced by species relative seasonal abundance and behavior. We recommend airport wildlife officials evaluate the risks mammal species pose to aircraft based on the hazard information we provide and consider prioritizing management strategies that emphasize reducing their occurrence on airport property.
[Show abstract][Hide abstract] ABSTRACT: Radiotelemetry and unmarked occupancy modeling have been used to estimate animal population growth, but have not been compared for ungulates. We compared white-tailed deer (Odocoileus virginianus) population growth estimates from radiomarked individuals and occupancy modeling of unmarked individuals and evaluated advantages and disadvantages of each method. Estimates of population growth were obtained using remote camera (N = 54/year) detection/non-detection occupancy surveys of unmarked deer and from survival and recruitment data of radiomarked adult females (N = 87) and neonate fawns (N = 127) in a predominantly forested region of the Upper Peninsula of Michigan, USA, 2009–2011. We hypothesized that occupancy models and radiotelemetry data would have similar population growth trends because both methods sampled the same temporally closed population. Percent changes in camera trap data generally reflected finite population growth (λ) of radiomarked deer which increased (λ = 1.10 ± 0.01) from 2009 to 2010, but decreased (λ = 0.87 ± 0.02) from 2010 to 2011. Also, unmarked adult female abundance and fawn:adult female ratios generally reflected trends in radiomarked deer survival and recruitment. Royle–Nichols occupancy model abundance estimates had wide confidence intervals, which may preclude using this method from accurately estimating deer population growth. Radiotelemetry provided more precise population growth estimates, while allowing collection of vital rates and location data. However, the Royle–Nichols occupancy model may be preferred to radiotelemetry because it reflected yearly variation in population growth with reduced labor and no invasive marking. Researchers should consider the objectives and logistics of their study when choosing a specific method.
Population Ecology 07/2014; 56(3). · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We documented the seasonal food habits of the red panda Ailurus fulgens based on the analysis of 152 fecal pellet groups in Rara National Park, Nepal, using micro-histological techniques. We also reviewed previous studies documenting the degree of specialization in red panda diets throughout their range. We found that bamboo was the major food item for red pandas in Rara National Park, occurring in 100% of pellet groups in both the pre- and post-monsoon seasons. Similarly, bamboo was also reported as the dominant food item (80–100%) in the diet of red pandas in seven studies conducted throughout their range. These results confirm previous findings and suggest that red pandas may be vulnerable to bamboo loss through anthropogenic impacts, which could influence their survival.
[Show abstract][Hide abstract] ABSTRACT: Understanding factors that influence recruitment can improve wildlife conservation. Endangered black-footed ferrets (Mustela nigripes) rely on prairie dogs (Cynomys spp.) for food and on prairie dog burrows for shelter. We hypothesized that younger female ferrets with greater densities of prairie dogs in their core use area and fewer adult ferrets in their respective prairie dog colony, would produce more kits due to age-dependent productivity, increased food resources, and decreased competition. We used generalized linear mixed-effects regression and Akaike’s information criterion adjusted for sample size (AICc) to rank models relating adult female black-footed ferret litter size (range 1–7 kits, n = 24 litters) to female age, core area density of prairie dogs, and adult ferret densities from 3 sites in the USA, 2005–2008. We included year and site as random effects in all models. We observed great model uncertainty; the null model was most supported and received 44% of model weight (w). The next best-supported model included ferret density only (ΔAICc = 1.55, w = 0.20). Ferret density may not have been great enough to negatively affect prey acquisition and litter sizes. Mean litter size did not vary among female ages, but inference was limited because only one individual
was >3 years old (x– = 2.13 years, SD = 0.99). All adult females produced kits, suggesting that the observed minimum prairie dog density in ferret core use areas (12.3 individuals ⋅ ha–1) was above a threshold of minimal prey abundance for reproduction. Our findings support previous selections of reintroduction sites as those meeting minimum resource needs of individual ferrets for reproduction. Future selections of reintroduction sites may become more difficult if the number of areas with the minimum necessary prairie dog density decreases due to disease and reductions in habitat availability.
Western North American Naturalist 05/2014; 74:108-115. · 0.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bottlenecks, founder events, and genetic drift often result in decreased genetic diversity and increased population differentiation. These events may follow abundance declines due to natural or anthropogenic perturbations, where translocations may be an effective conservation strategy to increase population size. American black bears (Ursus americanus) were nearly extirpated from the Central Interior Highlands, USA by 1920. In an effort to restore bears, 254 individuals were translocated from Minnesota, USA and Manitoba, Canada, into the Ouachita and Ozark Mountains from 1958 to 1968. Using 15 microsatellites and mitochondrial haplotypes, we observed contemporary genetic diversity and differentiation between the source and supplemented populations. We inferred four genetic clusters: Source, Ouachitas, Ozarks, and a cluster in Missouri where no individuals were translocated. Coalescent models using approximate Bayesian computation identified an admixture model as having the highest posterior probability (0.942) over models where the translocation was unsuccessful or acted as a founder event. Nuclear genetic diversity was highest in the source (AR = 9.11) and significantly lower in the translocated populations (AR = 7.07 - 7.34; P = 0.004). The Missouri cluster had the lowest genetic diversity (AR = 5.48) and served as a natural experiment showing the utility of translocations to increase genetic diversity following demographic bottlenecks. Differentiation was greater between the two admixed populations than either compared to the source, suggesting that genetic drift acted strongly over the eight generations since the translocation. The Ouachitas and Missouri were previously hypothesized to be remnant lineages. We observed a pre-translocation remnant signature in Missouri but not in the Ouachitas.This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: The Vulnerable red panda Ailurus fulgens is endemic to the Himalayas. Anthropogenic activities, including deforestation, have degraded the species’ habitat but the effects of livestock have not been examined. We assessed the effects of illegal livestock activity on the presence of the red panda in Rara National Park, Nepal. The probability of detecting red panda faecal pellets decreased with livestock occurrence but not with elevation or aspect. The presence of bamboo and proximity to water are important to red pandas but did not influence their habitat use at the spatial resolution evaluated. Livestock grazing in Rara National Park appears to adversely affect the presence of the red panda within its habitat. To reduce illegal livestock grazing we recommend enforcement of existing regulations, that training workshops be held for herders, and awareness-raising and dialogue with residents.
[Show abstract][Hide abstract] ABSTRACT: American black bears (Ursus americanus) were nearly extirpated from Missouri
(USA) by the early 1900s and began re-colonizing apparent suitable habitat in southern
Missouri following reintroduction efforts in Arkansas (USA) during the 1960s. We used
anecdotal occurrence data from 1989 to 2010 and forest cover to describe broad patterns of
black bear re-colonization, human–bear incidents, and bear mortality reports in Missouri.
Overall, 1,114 black bear occurrences (including 118 with dependent young) were reported, with
95% occurring within the Ozark Highlands ecological region. We created evidentiary standards
to increase reliability of reports, resulting in exclusion of 21% of all occurrences and 13% of
dependent young. Human–bear incidents comprised 5% of total occurrences, with 86%
involving bears eating anthropogenic foods. We found support for a northward trend in
latitudinal extent of total occurrences over time, but not for reported incidents. We found a
positive correlation between the distribution of bear occurrences and incidents. Twenty bear
mortalities were reported, with 60% caused by vehicle collisions. Black bear occurrences have
been reported throughout most of Missouri’s forested areas, although most reports of
reproduction occur in the southern and eastern Ozark Highlands. Though occurrence data are
often suspect, the distribution of reliable reports supports our understanding of black bear
ecology in Missouri and reveals basic, but important, large-scale patterns important for
establishing management and research plans.
[Show abstract][Hide abstract] ABSTRACT: Several airports in the US have recently installed large photovoltaic (PV) arrays near air-operations areas to offset energy demands, and the US Federal Aviation Administration has published guidelines for new solar installations on airport properties. Although an increased reliance on solar energy will likely benefit airports from environmental and economic perspectives, bird use of solar installations should be examined before wide-scale implementation to determine whether such changes in land use adversely affect aviation safety by increasing risk of bird-aircraft collisions. We studied bird use of five pairs of PV arrays and nearby airport grasslands in Arizona, Colorado, and Ohio, over one year. Across locations, we observed 46 species of birds in airfield grasslands compared to 37 species in PV arrays. We calculated a bird hazard index (BHI) based on the mean seasonal mass of birds per area surveyed. General linear model analysis indicated that BHI was influenced by season, with higher BHI in summer than fall and winter. We found no effect of treatment (PV arrays vs. airfields), location, or interactions among predictors. However, using a nonparametric two-group test across all seasons and locations, we found greater BHI in airfield grasslands than PV arrays for those species considered especially hazardous to aircraft (species ≥ 1.125 kg). Our results suggest that converting airport grasslands to PV arrays would not increase hazards associated with bird-aircraft collisions.
Landscape and Urban Planning 02/2014; 122:122–128. · 2.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Growth of ungulate populations is typically most sensitive to survival of neonates, which in turn is influenced by maternal nutritional condition and trade-offs in resource selection and avoidance of predators. We assessed whether resource use, multi-predator risk, maternal nutritional effects, hiding cover, or interactions among these variables best explained variation in daily survival of free-ranging neonatal white-tailed deer (Odocoileus virginianus) during their post-partum period (14 May-31 Aug) in Michigan, USA. We used Cox proportional hazards mixed-effects models to assess survival related to covariates of resource use, composite predation risk of 4 mammalian predators, fawn body mass at birth, winter weather, and vegetation growth phenology. Predation, particularly from coyotes (Canis latrans), was the leading cause of mortality; however, an additive model of non-ideal resource use and maternal nutritional effects explained 71% of the variation in survival. This relationship suggested that dams selected areas where fawns had poor resources, while greater predation in these areas led to additive mortalities beyond those related to resource use alone. Also, maternal nutritional effects suggested that severe winters resulted in dams producing smaller fawns, which decreased their likelihood of survival. Fawn resource use appeared to reflect dam avoidance of lowland forests with poor forage and greater use by wolves (C. lupus), their primary predator. While this strategy led to greater fawn mortality, particularly by coyotes, it likely promoted the life-long reproductive success of dams because many reached late-age (>10 years old) and could have produced multiple generations of fawns. Studies often link resource selection and survival of ungulates, but our results suggested that multiple factors can mediate that relationship, including multi-predator risk. We emphasize the importance of identifying interactions among biological and environmental factors when assessing survival of ungulates.
PLoS ONE 01/2014; 9(6):e100841. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: From foraging theory, generalist predators should increase consumption of prey if prey availability increases. Pulsed resource events introduce a large influx of prey to predators that may exhibit a functional response of increased consumption rate on, or specialization to, this abundant food resource. We predicted that coyotes (Canis latrans) would respond functionally to numerical increases of neonate white-tailed deer (Odocoileus virginianus) during the pulsed resource event of parturition. We used howl surveys and deer camera surveys with occupancy modeling to estimate densities for coyotes, adult deer, and fawns, respectively, in Upper Peninsula of Michigan, USA, 2009–2011. We estimated biomass of adult and fawn deer consumed by coyotes during 2 periods [fawn limited mobility period (LMP) and social mobility period (SMP)] in May–August each year. Coyote densities were 0.32 and 0.37/km2 for 2010–2011, respectively. Adult deer densities (3.7–3.9/km2) and fawn densities (0.6–1.3/km2) were similar across years. Overall, fawn hair occurrence in coyote scats was 2.3 times greater in LMP than SMP. Estimated consumption of fawns between periods (n = 157–880) by coyotes varied, suggesting a functional response, with increasing consumption of fawns relative to their availability. Coyotes, on average, consumed 2.2 times greater biomass of fawns than adults across years, and consumed 1.5 times greater fawn biomass, on average, during LMP than SMP. We suggest that consumption rates of coyotes is associated positively with increases in fawn density, and fawn consumption by coyotes follows predictions of optimal foraging theory during this pulsed resource event.
[Show abstract][Hide abstract] ABSTRACT: Effective methods for estimating occurrence and abundance of carnivores are limited and
often expensive in labour or equipment. Conducting interviews about wildlife species, including carnivores,
is a common tool used in Borneo and throughout Southeast Asia to investigate species distribution and
understand their conservation status. Such surveys are appealing because of perceived savings in time
and equipment; however, biases in amount of available information, miscommunications about species of
interest, and species misidentifi cation can result in errors of unknown magnitude, rendering results of at
least some surveys suspect. Hence, it becomes diffi cult to disentangle accurate from inaccurate information.
Studies are needed to investigate the variation in effectiveness of interview surveys. Also better guidance
is needed to clarify under which conditions secondary surveys can be used with confi dence, and for which
particular audience. Until the factors that bias results are identifi ed and, where possible, accounted for, the
main use of secondary surveys for carnivores and other diffi cult to identify or rarely encountered species
will be to help develop a dialogue between people that reside or work in conservation project areas and
the investigators working on such projects. Secondary surveys may also serve as a tool to help identify
hypotheses to be addressed in studies with strong experimental designs.
The Raffles bulletin of zoology 10/2013; supplement 28. · 0.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: More than 90% of harlequin frog species (Atelopus spp.), endemic to the Americas, are currently threatened with extinction. We report the discovery of the only currently known breeding population of the Critically Endangered A. varius in Costa Rica. This population was located in 2008 on a private property in Las Tablas Protected Zone near San Vito, Coto Brus at 1300 m elevation. Previously, the only known remaining/remnant population of this species and genus was a single location near Manuel Antonio, Puntarenas, Costa Rica, where two individuals were documented in 2004. Subsequent searches at this location have yielded no additional sightings. Delineating the spatial limits of this population, quantifying demographics and resource use, and implementing conservation actions are necessary to ensure persistence of this population. Conducting additional surveys in this region to ascertain occurrence of additional populations is warranted. Amphibian species worldwide are declining more rapidly in general than other vertebrate groups, with 31% of known species threatened with extinction (Hoffmann et al., 2010; IUCN, 2011). Decline of amphibians is at the fore-front of the global biodiversity crisis and has received considerable attention (Stuart et al., 2004). Many studies have reported amphibian declines and proposed sweeping efforts to save species or populations (e.g., Lips et al., 2003; Stuart et al., 2004). While current research em-phasizes understanding and mitigating amphib-ian declines, less attention has been given to searching for populations and species where 1 -The Sierra to Sea Institute & ProCAT Interna-tional/Colombia, De Intel 100 m Oeste, Hda. Belén 8 a ,
[Show abstract][Hide abstract] ABSTRACT: In comparison with large carnivores (order Carnivora), small carnivores are generally considered as less charismatic, and with the exception of a few social species (e.g. meerkats, European badger), they have been subjected to proportionately less research work. However, small carnivores play important roles in ecosystem function (e.g. seed dispersal), predator–prey dynamics, and in relation to peo¬ple (e.g. hunting, disease transmission). At the same time, a wide variety of anthropogenic threats (e.g. harvest, habitat loss and fragmentation, climate change) demonstrably effect small carnivore spe¬cies adversely. This symposium aims at bringing together contributions dealing with several aspects of small carnivore evolution, ecology, and conservation biology related to spatial and/or temporal factors/scales (niche differentiation, space use, activity and movement patterns, distribution, phylogeography, etc.). The species of interest predominantly include badgers, martens, otters and allies (Mustelidae), civets, genets and allies (Viverridae), mongooses (Herpestidae), raccoons (Procyonidae), and skunks (Mephitidae).
11th International Mammalogical Congress, Belfast, Northern Ireland; 08/2013
[Show abstract][Hide abstract] ABSTRACT: Background/Question/Methods
The hypothesis that discrete intrapopulation differences in dietary niches can facilitate genetic differentiation relates to a fundamental debate on the drivers of genetic diversity. In the Stikine watershed in northwest British Columbia, salmon (Oncorhynchus spp.) penetrate the region along linear river systems, resource availability occurs along a coastal–inland gradient, but also across a finer-scale gradient in elevation. We hypothesized the coastal-inland and elevation gradients would create an interwoven matrix of brown bears (Ursus arctos) that specialize on salmon or terrestrial resources. Our objectives were to: (1) discern whether this population exhibits trophic polymorphisms resultant from marine and terrestrial-based dietary specializations, (2) evaluate whether there is evidence of non-random mating within the population, (3) if there is evidence of non-random mating, determine if distinct genetic clusters correspond with discrete dietary niches, and (4) identify what intrinsic and extrinsic factors best explain intrapopulation dietary niche variation. Genetic and stable isotope data were derived from guard hair from systematically distributed sampling stations. We estimated diet using a Bayesian-based mixing model and evaluated genetic population structure using programs Structure and Genepop. We used hierarchical Bayesian modeling to assess alternative models of the influence of intrinsic and extrinsic factors on bear diets.
Our preliminary results show that discrete intrapopulation dietary niches within this bear population reflect dietary specializations on salmon or terrestrial food resources. Using program Structure, we identified two distinct genetic clusters within this grizzly bear population. Further analysis using program Genepop revealed differences (P < 0.001) in allelic frequencies between the two distinct genetic clusters, providing strong evidence against a single, random mating population. Although hierarchical analyses are ongoing, our preliminary assessment is that both intrinsic (e.g., sex-class) and extrinsic (e.g., elevation) factors are influencing intrapopulation dietary niche variation in this population of brown bears. Our work provides new insights into the ecological drivers of life history diversification and offers an alternative mechanism to the traditional concept that genetic differentiation requires physical separation of populations.