Dale R. McCullough’s research while affiliated with University of California, Berkeley and other places

Ungulates exhibit diverse mating systems that range from monogamous pair territories to highly polygynous leks. We review mating systems and behaviors across ungulates and offer a new approach synthesizing how interacting factors may shape those mating systems. Variability exists in mating systems among and within species of ungulates and likely is affected by predation risk, availability of resources (food and mates), habitat structure, and sociality. Ungulate mating systems may be labile as a consequence of the varying strength of those interacting factors. In addition, degree of polygyny and sexual dimorphism in size are associated with the evolution of mating systems. Neither male–male combat nor paternal care, however, can completely explain differences in sexual size dimorphism for ungulates, a necessary component in understanding the development of some mating systems. Whatever the evolutionary pathway, sexual segregation limits paternal care allowing more intense male–male competition. Selection of habitat structure, because it modifies risk of predation, is a major determinant of sociality for ungulates. Likewise, ruggedness and steepness of terrain limit the types of mating systems that can occur because of limitations in group size and cohesiveness, as well as the ability of males to herd even small groups of females effectively. The quality and defensibility of resources affect mating systems, as does the defensibility of females. Population density of females also may be a critical determinant of the types of mating systems that develop. Size of groups likewise constrains the types of mating tactics that males can employ. Our aim was to use those relationships to create a broad conceptual model that predicts how various environmental and social factors interact to structure mating systems in ungulates. This model provides a useful framework for future tests of the roles of both ecological and social conditions in influencing the social systems of ungulates.

Amur tigers and Far Eastern leopards are sympatric in the Russian Far East. Different ecological characteristics, such as different resource use, may enable coexistence of these two large predators, as indicated in other tiger–leopard habitats in Asia. We examined the winter food habits of tigers and leopards in the sympatric range in Southwest Primorskii Krai, Russian Far East using feces collected during four winters (2000–01, 2001–02 2002–03, and 2004–05). Fecal samples were identified as either tiger or leopard by genetic analysis, and we examined 63 and 139 samples of tiger and leopard feces, respectively. We found that leopards preyed on 13 species and tigers on 8 species. Wild boar and sika deer were the most frequently consumed prey for tigers and leopards, respectively. Three ungulates (sika deer, roe deer, and wild boar) appeared to be the essential prey because they provided a large proportion of the relative biomass consumed by tigers (92%) and leopards (87%). Tigers showed a strong preference for wild boar (Jacobs index: +0.55), whereas leopards did not show such a strong preference for any particular ungulate species. Moreover, both species consumed mid-sized carnivores and small mammals, with leopards consuming a more diverse range of prey, including squirrels, rodents, birds, and clams, none of which were identified in the tiger feces. There was a significant difference in the composition of their prey, suggesting resource partitioning between the two predators; however, Pianka's niche overlap index was high (0.77) because both species heavily relied on the three ungulates. Our study suggests that the availability of three different ungulate species, the tigers’ preference for wild boar, and the diverse prey base of leopards contribute to the coexistence of tigers and leopards in this region.

For long-lived species, environmental factors experienced early in life can have lasting effects persisting into adulthood. Large herbivores can be susceptible to cohort-wide declines in fitness as a result of decreases in forage availability, because of extrinsic factors, including extreme climate or high population densities. To examine effects of cohort-specific extrinsic factors on size of adults, we performed a retrospective analysis on harvest data of 450 male black-tailed deer ( Odocoileus hemionus columbianus ) over 19 years in central California, USA. We determined that population density of females had a more dominant effect than did precipitation on body size of males. Harvest of female deer resulted in increases in the overall size of males, even though a 6-year drought occurred during that treatment period. Body size was most influenced by female population density early in life, while antler size was highly affected by both weather early in life and the year directly before harvest. This study provides insights that improve our understanding of the role of cohort effects in body and antler size by cervids; and, in particular, that reduction in female population density can have a profound effect on the body and antler size of male deer.

Understanding and monitoring the population status of endangered species is vital for developing appropriate management interventions. We used noninvasive genetic analyses to obtain ecological and genetic data on the last remaining Far Eastern leopard population in the world. During seven winters from 2000–2001 to 2007–2008, we collected feces, hair, and saliva from most of the leopard habitat. Of the 239 leopard samples collected during the study period, 155 were successfully genotyped at 13 microsatellite loci and 37 individuals (18 males and 19 females) were identified. Population size estimates based on the Capwire model were 28 (95 % CI 19–38) in 2002–03 and 26 (95 % CI 13–33) in 2007–2008. The leopard population had a low level of genetic diversity (expected and observed heterozygosity = 0.43; average number of alleles per locus = 2.62), and effective population size was estimated to be low (N e = 7–16) by two genetic-based methods. We observed little improvement in the genetic diversity during the study period and did find an indication of allele loss compared with individuals from the mid-1990s, suggesting that the remaining population will continue to suffer loss of genetic diversity. Given the small population size and the low genetic diversity, with little expectation of replenishment of the genetic variation by natural immigration, successful expansion of available habitat and development of a second population based on captive individuals may be crucial for persistence of this leopard subspecies in the wild.

The Amur tiger, Panthera tigris altaica, is currently distributed across the southern part of the Russian Far East and parts of northeastern China. Most Amur tigers are found in Russia, where their range is fragmented into at least 3 populations (a large population centered in the Sikhote-Alin Mountains and 2 smaller populations in northwest and southwest Primorye Krai). Traditionally, track-based techniques have been used for surveys of tigers in Russia. However, such techniques involve problems such as misinterpretation of track sizes due to snow degradation, and thus, other survey protocols have been needed. This study aimed to identify individuals and estimate population size using noninvasive genetic samples, such as feces, hairs, and saliva, collected from southwest Primorye Krai during 4 winters (2000-2001, 2001-2002, 2002-2003, and 2004-2005). During these winters, we identified 12 tigers (5 males and 7 females) using 10 microsatellite markers. Population size estimated from the 2002-2003 samples was 12 (95% confidence interval = 9-19), which was comparable to the estimate from the track count survey. Of the 3 types of noninvasive genetic samples we collected, feces were the most useful in terms of genotyping success rate and sampling efficiency. The noninvasive genetic methods developed in this study can contribute to population monitoring and management assessment of tiger conservation in the Russian Far East.

To accommodate an increased food intake with greater body size, rumen–reticulum capacity must become larger to allow heavier digesta loads. Recently, digesta load was found to correlate with age more strongly than body size. It was suggested that older animals had compromised mastication efficiency due to tooth wear and compensated for larger particles by increasing rumen–reticulum capacity to extend retention time. Herein, we constructed models and used Akaike Information Criteria corrected for small sample size to determine if digesta load was related with age or body weight in 80 female and 105 male black-tailed deer (Odocoileus hemionus columbianus). We also assessed if the presence of fetuses influenced relationships in females. Females were collected in spring, 1985–1988, and males were collected in autumn, 1980, 1982–1984, and 1988, from Hopland Research and Extension Center, Mendocino County, California. Digesta loads, fetuses, and carcasses were weighed, and animal ages were estimated. Digesta load was related to age in females and body weight in males. Our study shows that body size and age-related factors may both influence rumen–reticulum capacity.

ABSTRACT  Understanding colonization is vital for managing fragmented populations. We employed mitochondrial DNA haplotypes and 14 microsatellite (nuclear DNA) markers to infer the origins of newly established populations of desert bighorn sheep (Ovis canadensis nelsoni) and to assess loss of genetic diversity during natural colonizations. We used haplotype distribution, F-statistics, Bayesian population clustering, and assignment tests to infer source populations for 3 recent colonies and identified a previously undetected colonization from multiple source populations. Allelic richness declined in 3 of 4 colonies in comparison to the primary source populations, but not as much as has been reported for translocated populations. Heterozygosity declined in only one colony. We also demonstrated that both native and translocated desert bighorn sheep have naturally recolonized empty habitats and suggest that colonization may partially offset population extinction in the region as long as connectivity is maintained. Genetic techniques and mitochondrial DNA haplotypes we described will allow managers to determine the origins of future colonizations by bighorn sheep in California, USA, and prioritize protection of linkages between known sources and colonies.

Resolving conflicts between predators and livestock producers depends on obtaining reliable information about the predators that kill livestock. We used salivary DNA obtained from attack wounds on domestic sheep carcasses to identify the species of predator responsible for the kill, as well as the sex and individual identity of coyotes (Canis latrans) that killed sheep. Coyotes killed 36 of 37 depredated sheep. Breeding pairs whose territories overlapped sheep grazing areas were the primary predators on domestic sheep, and only breeding pairs killed multiple sheep. Breeding males, acting alone or with their mate, were involved in 21 of 25 kills. Breeding females participated in 13 kills, but only 1 breeding female killed sheep on her own. Transient females did not kill sheep, and both kills by transient males occurred in territories with a breeding vacancy. Our results suggest that predator control should be targeted at breeding male coyotes. Salivary DNA is a potentially powerful means of both investigating predation patterns and evaluating the effectiveness of control at targeting individuals that kill livestock.

The Amur tiger (Panthera tigris altaica) is a critically endangered felid that suffered a severe demographic contraction in the 1940s. In this study, we sampled 95 individuals collected throughout their native range to investigate questions relative to population genetic structure and demographic history. Additionally, we sampled targeted individuals from the North American ex situ population to assess the genetic representation found in captivity. Population genetic and Bayesian structure analyses clearly identified two populations separated by a development corridor in Russia. Despite their well-documented 20th century decline, we failed to find evidence of a recent population bottleneck, although genetic signatures of a historical contraction were detected. This disparity in signal may be due to several reasons, including historical paucity in population genetic variation associated with postglacial colonization and potential gene flow from a now extirpated Chinese population. Despite conflicting signatures of a bottleneck, our estimates of effective population size (N(e) = 27-35) and N(e)/N ratio (0.07-0.054) were substantially lower than the only other values reported for a wild tiger population. Lastly, the extent and distribution of genetic variation in captive and wild populations were similar, yet gene variants persisted ex situ that were lost in situ. Overall, our results indicate the need to secure ecological connectivity between the two Russian populations to minimize loss of genetic diversity and overall susceptibility to stochastic events, and support a previous study suggesting that the captive population may be a reservoir of gene variants lost in situ.