Explore the vast range of titles available.

The genetic composition of an individual can markedly affect its survival, reproduction, and ultimately fitness. As some wildlife populations become smaller, conserving genetic diversity will be a conservation challenge. Many imperiled species are already supported through population augmentation efforts and we often do not know if or how genetic diversity is maintained in translocated species. As a case study for understanding the maintenance of genetic diversity in augmented populations, I wanted to know if genetic diversity (i.e., observed heterozygosity) remained high in a population of gray wolves in the Rocky Mountains of the U.S. > 20 years after reintroduction. Additionally, I wanted to know if a potential mechanism for such diversity was individuals with below average genetic diversity choosing mates with above average diversity. I also asked whether there was a preference for mating with unrelated individuals. Finally, I hypothesized that mated pairs with above average heterozygosity would have increased survival of young. Ultimately, I found that females with below average heterozygosity did not choose mates with above average heterozygosity and wolves chose mates randomly with respect to genetic relatedness. Pup survival was not higher for mated pairs with above average heterozygosity in my models. The dominant variables predicting pup survival were harvest rate during their first year of life and years pairs were mated. Ultimately, genetic diversity was relatively unchanged > 20 years after reintroduction. The mechanism for maintaining such diversity does not appear related to individuals preferentially choosing more genetically diverse mates. Inbreeding avoidance, however, appears to be at least one mechanism maintaining genetic diversity in this population.

Noninvasive genetic sampling (NGS) is commonly used to study elusive or rare species where direct observation or capture is difficult. Little attention has been paid to the potential effects of observer bias while collecting noninvasive genetic samples in the field, however. Over a period of 7 years, we examined whether different observers (n = 58) and observer experience influenced detection, amplification rates, and correct species identification of 4,836 gray wolf (Canis lupus) fecal samples collected in Idaho and Yellowstone National Park, USA and southwestern Alberta, Canada (2008-2014). We compared new observers (n = 33) to experienced observers (n = 25) and hypothesized experience level would increase the overall success of using NGS techniques in the wild. In contrast to our hypothesis, we found that new individuals were better than experienced observers at detecting and collecting wolf scats and correctly identifying wolf scats from other sympatric carnivores present in the study areas. While adequate training of new observers is crucial for the successful use of NGS techniques, attention should also be directed to experienced observers. Observer experience could be a curse because of their potential effects on NGS data quality arising from fatigue, boredom or other factors. The ultimate benefit of an observer to a project is a combination of factors (i.e., field savvy, local knowledge), but project investigators should be aware of the potential negative effects of experience on NGS sampling.

The camera trap is a powerful research tool that has a wide range of ecological applications and facilitates monitoring over large spatial and temporal scales. To improve the reliability of camera trap studies and provide more knowledge on camera performance, we evaluated three aspects of camera traps that researchers should consider – camera height, blank images and missed detections. We deployed 20 camera stations, each consisting of one low camera (0.6 m) and two adjacent high cameras (3 m). We tested for differences in detection rates and blank images between camera heights. We calculated missed detections using the two high cameras and used a subset of cameras (n = 14) to examine whether missed detections were caused by late triggers or failed triggers. We found that placing cameras high to minimize theft and damage did not influence detection rates. There were, however, more blank images which can increase the time required for analysis. These blank images increased as temperature increased. Missed detections were primarily the result of failed triggers and increased as species size decreased. Failed detections are particularly significant for distribution surveys of low‐density species. Detection at the camera is imperfect, even when working with larger species. We evaluated three aspects of camera traps that researchers should consider – camera height, blank images and missed detections. We deployed 20 camera stations, each consisting of one low camera (0.6 m) and two adjacent high cameras (3 m). We found that placing cameras high did not influence detection rates and high cameras generated more blank images which increased as temperature increased. Missed detections increased as species size decreased and were primarily the result of failed triggers as opposed to late triggers. We recommend that cameras used for documenting species presence be placed at 2.5 m and above and urge researchers to avoid assumptions of certain detectability inside the detection zone, even when working with larger species.

Knowledge of snow cover distribution and disappearance dates over a wide range of scales is imperative for understanding hydrological dynamics and for habitat management of wildlife species that rely on snow cover. Identification of snow refugia, or places with relatively late snow disappearance dates (SDDs) compared to surrounding areas, is especially important as climate change alters snow cover timing and duration. The purpose of this study was to increase understanding of snow refugia in complex terrain spanning the rain-snow transition zone at fine spatial and temporal scales. To accomplish this objective, we used remote cameras to provide relatively high temporal and spatial resolution measurements on snowpack conditions. We built linear models to relate SDDs at the monitoring sites to topoclimatic and canopy cover metrics. One model to quantify SDDs included elevation, aspect, and an interaction between canopy cover and cold-air pooling potential. High-elevation, north-facing sites in cold-air pools (CAPs) had the latest SDDs, but isolated lower-elevation points also exhibited relatively late potential SDDs. Importantly, canopy cover had a much stronger effect on SDDs in CAPs than in non-CAPs, indicating that best practices in forest management for snow refugia could vary across microtopography. A second model that included in situ hydroclimate observations (December – February (DJF) temperature and March 1 snow depth) indicated that March 1 snow depth had little impact on SDD at the coldest winter temperatures, and that DJF temperatures had a stronger effect on SDD at lower snow depths, implying that the relative importance of snowfall and temperature could vary across hydroclimatic contexts in their impact on snow refugia. This new understanding of factors influencing snow refugia can guide forest management actions to increase snow retention and inform management of snow-dependent wildlife species in complex terrain.

Monitoring the abundance of rare carnivores is a daunting task for wildlife biologists. Many carnivore populations persist at relatively low densities, public interest is high, and the need for population estimates is great. Recent advances in trail camera technology provide an unprecedented opportunity for biologists to monitor rare species economically. Few studies, however, have conducted rigorous analyses of our ability to estimate abundance of low‐density carnivores with cameras. We used motion‐triggered trail cameras and a space‐to‐event model to estimate gray wolf (Canis lupus) abundance across three study areas in Idaho, USA, 2016–2018. We compared abundance estimates between cameras and noninvasive genetic sampling that had been extensively tested in our study areas. Estimates of mean wolf abundance from camera and genetic surveys were within 22% of one another and 95% CIs overlapped in 2 of the 3 years. A single camera with many detections appeared to bias camera estimates high in 2018. A subsequent bootstrapping procedure produced a population estimate from cameras equal to that derived from genetic sampling, however. Camera surveys were less than half the cost of genetic surveys once initial camera purchases were made. Our results suggest that cameras can be a viable method for estimating wolf abundance across broad landscapes (>10,000 km2).

Offspring sex ratios can vary widely across species, and the reasons for such variation have long intrigued ecologists. For group-living animals, predicting offspring sex ratios as a function of group and environmental characteristics can be challenging. Additionally, mortality of group members can upend traditional theory used to explain offspring sex ratios observed in populations. Gray wolves (Canis lupus) in Idaho, USA, are an excellent study species for asking questions about offspring sex ratios given their group-living behavior and persistent exposure to human-caused mortality. I hypothesized that offspring sex ratios would be influenced by the characteristics of individuals, groups, and populations. I generated genotypes for 419 adult and 400 pup wolves during 2008–2018. There was a significant male-bias in litters of wolf pups with nearly 12% more male pups born than females. The individual, group, and population variables I considered did not have significant associations with offspring sex ratios. Local resource competition helped explain offspring sex ratios in wolves in my study system, but not local resource enhancement theory. Although female helpers have been shown to help slightly more than males, offspring sex ratios did not favor the helping sex suggesting that the overall benefit of female helpers may have been negligible in wolf groups during my study. Three wolf groups consistently overproduced males, the dispersing sex, suggesting that habitat quality was poor in their territories. The male-biased offspring sex ratios observed throughout this population reflect sex-biased dispersal in wolves in Idaho. Such a pattern suggests breeding females may be reducing local resource competition (e.g., mates and successful reproduction) by producing more males than females.Significance statementNatural selection can favor biased offspring sex ratios in some species. This may be particularly true for animals that live and breed in groups such as gray wolves. Using genetic sampling, I show that offspring sex ratios in wolves are male-biased and reflect sex-biased dispersal in wolves. Breeding females may be reducing future local resource competition for mates by producing significantly more offspring of the dispersing sex (males).

Wildlife populations are increasingly threatened by human activities. Most studies, however, are often short in duration or do not encompass the large spatial extent necessary to measure the potential effects of human activities on population vital rates. Furthermore, the life history features of species with high fecundity and excellent dispersal capabilities can act as buffers against the potential negative effects of human activities on their populations. We used a 30‐year dataset of genetic samples from gray wolves (Canis lupus) in Alaska, USA, to examine genetic connectivity and diversity between National Park units separated by a region with recurrent human‐caused mortality. We found that the two protected populations were genetically similar and that dispersal events occurred between them even though they are > 450 km apart. We posit that intact ecosystems and a history of continuous distribution of wolves surrounding the affected regions likely maintained the genetic connectivity of wolves in the two protected areas. We used a 30‐year dataset of genetic samples from gray wolves (Canis lupus) in Alaska, USA to examine genetic connectivity and diversity between National Park units separated by a region with recurrent human‐caused mortality. We found that the two protected populations were genetically similar and that dispersal events occurred between them even though they are > 450 km apart. We posit that intact ecosystems and a history of continuous distribution of wolves surrounding the affected regions likely maintained the genetic connectivity of wolves in the two protected areas.

Various monitoring methods have been developed for large carnivores, but not all are practical or sufficiently accurate for long-term monitoring over large spatial scales. From 2009 to 2010, we used a predictive habitat model to locate gray wolf rendezvous sites in 4 study areas in Idaho, USA and conducted noninvasive genetic sampling (NGS) of scat and hair found at the sites. We evaluated species and individual identification PCR success rates across the study areas, and estimated population size with a single-session population estimator using 2 different recapture-coding methods. We then compared NGS population estimates to estimates generated concurrently from telemetry data. We collected 1,937 scat and 166 hair samples and identified 193 unique individuals over 2 years. For fecal DNA samples, species identification success rates were consistently high (>92%) across areas. Individual identification success rates ranged from 78% to 80% in the drier study areas and dropped to 50% in the wettest study area. The degree of agreement between NGS- and telemetry-derived population estimates varied by recapture-coding method with considerable variability in 95% confidence intervals. Population estimates derived from NGS methods were most influenced by the average number of detections per individual. We demonstrate how changes in field effort and recapture-coding method can affect population estimates in a widely used single-session population estimation model. Our study highlights the need to further develop reliable population estimation tools for single-session NGS data, especially those with large differences in capture frequencies among individuals stemming from severe capture heterogeneity (i.e., overdispersion).

Traditional methods of monitoring gray wolves (Canis lupus) are expensive and invasive and require extensive efforts to capture individual animals. Noninvasive genetic sampling (NGS) is an alternative method that can provide data to answer management questions and complement already-existing methods. In a 2-year study, we tested this approach for Idaho gray wolves in areas of known high and low wolf density. To focus sampling efforts across a large study area and increase our chances of detecting reproductive packs, we visited 964 areas with landscape characteristics similar to known wolf rendezvous sites. We collected scat or hair samples from 20% of sites and identified 122 wolves, using 8–9 microsatellite loci. We used the minimum count of wolves to accurately detect known differences in wolf density. Maximum likelihood and Bayesian single-session population estimators performed similarly and accurately estimated the population size, compared with a radiotelemetry population estimate, in both years, and an average of 1.7 captures per individual were necessary for achieving accurate population estimates. Subsampling scenarios revealed that both scat and hair samples were important for achieving accurate population estimates, but visiting 75% and 50% of the sites still gave reasonable estimates and reduced costs. Our research provides managers with an efficient and accurate method for monitoring high-density and low-density wolf populations in remote areas.

Breeding strategies of cooperative breeders can vary widely ranging from multiple breeding pairs in a group, to polygamy, polyandry, and combinations of all 3 forms. Often, we do not have a clear understanding of the influences or mechanisms giving rise to the presence of multiple breeding individuals within groups. This is particularly true for animals that are difficult to manipulate or observe, such as large carnivores. I examined factors associated with the occurrence of multiple breeding individuals within groups in a population of recolonizing gray wolves (Canis lupus). Additionally, I investigated what might affect pup recruitment in groups with multiple breeding females. I used population monitoring data for wolves in Idaho and Yellowstone National Park, Wyoming, United States as well as genetic pedigree data for a subset of wolf groups that contained multiple breeding females in Idaho. High wolf density and large group size were both associated with a significant increase in the frequency of multiple breeding females in a group. The probability a pup survived their first year was related positively to the number of breeding females in a group. Multiple breeding can also take the form of polyandry, and “sneaker” males were responsible for paternity in nearly 13% of pups born. Breeding strategies in this social carnivore may be more variable than previously assumed, but their occurrence can be predicted by group size and density. Wolf population projection models and studies regarding reproduction and cooperative breeding in wolves would benefit by incorporating the potential for multiple breeding individuals. Genetic models in particular will be more reliable if they incorporate the potential effect of sneaker males on genetic diversity in a population.