My research involves fairly intensive field studies that entail morphometrics, mark-recapture methods, radio-tracking techniques, and GPS/GIS applications to understand population biology, wildlife-habitat relationships, and species recovery. A centerpiece for much of my research has been canid ecology, specifically red wolves and coyotes in the southeastern United States, but I'm also currently involved in ungulate research. Below are brief descriptions of some research areas that my work has contributed to.

Population biology

Recently, I used aerial survey data to estimate moose population size and trend in Adirondack Park, as well as white-tailed deer abundance. Moose exist as a sparsely distributed, low-density population across an extensive region of northern New York. Consequently, this required combining conventional distance sampling and spatial modelling methods to improve estimate precision and explain variation in ungulate density using spatial covariates.

Prior to this work, I used long-term monitoring of red wolves and coyotes to estimate population size and trend, as well as wolf survival [#10, 11]. My research showed that gunshot mortalities for red wolves became the leading cause of death for wolves after 2000. For red wolves, human-caused killings significantly reduced wolf survival during their breeding season, broke up packs, and allowed coyotes to encroach into areas where lone wolves were searching for mates. Some of the surviving red wolves pair-bonded with coyotes and the loss of wolf reproduction to hybridization was a form reproductive interference that typically accompanied human-caused killing of wolves.

Spatial ecology

Components of my research that investigate the spatial ecology of species involve trapping, radio-marking, and following known individuals. I use space use data to explain variation in animal behavior and population biology. For example, my research on red wolf-coyote interactions revealed that large home range requirements of wolves was an important factor limiting hybridization with coyotes [#15]. My research also reported that transiency is an important life-history strategy for red wolves and coyotes because the behavior allows populations to recover lost territories following mortality [#2, 7, 9, 10]. This strategy is important for coyote populations to persist where they are heavily exploited. The lack of transient animals is also problematic for recovering endangered red wolves when there aren't enough wolves on the landscape to fill in vacancies created by anthropogenic mortality [#9, 11].

Canid morphometrics

I use body measurements to document phenotypic variation and its covariation with other biotic and abiotic factors because morphormetric analyses are simple and highly reliable. My research showed that morphology is a valuable tool for discriminating among red wolves, coyotes, and their hybrids [#4]. F1 and F2 red wolf-coyote hybrids are incapable of reaching body sizes that are achieved by adult red wolves, as hybrids were "coyote-like" in size. This was an important finding because it suggests that the red wolf represents a unique Canis phenotype to the eastern United States and that differences in body-size measurements among taxa are highly suggestive of differences in ecological requirements.

In collaboration with the North American Canine Ancestry Project (NACAP), we extensively applied morphometric and genetic approaches to examine geographic variation in coyote morphology and genetics [#20]. This research found that southeastern coyotes represented a distinct genetic cluster that differentiated strongly from western and northeastern coyotes. Regarding morphology, southeastern coyotes were intermediate to western and northeastern coyotes in body size but exhibited shorter tails and ears from the other regional populations. We postulated that southeastern coyotes experienced lower immigration from western populations than did northeastern coyotes, and over time, genetically diverged from both western and northeastern populations.

Hybridization and reproductive isolation

During my dissertation research, I identified conditions facilitating hybridization between red wolves and coyotes [#15]. Red wolves exhibited size-assortative mating, a mating behavior widely observed in the animal kingdom and one known to act as a pre-mating reproductive barrier between distinct species and divergent populations. Despite being outnumbered by coyotes, 79% of observed red wolf pairings were conspecific with the majority of wolf-coyote pairings involving wolves <27.5 kg (60.6 lb). The effects of body size manifested in red wolf and coyote space use, as no coyote home ranges were >48 sq. km. Red wolf home ranges were typically >48 sq. km and wolves that consorted with coyotes maintained home ranges between 25-48 sq. km. This suggested that successful pairing with coyotes required red wolves to use smaller territories, and likely smaller prey, to accommodate their smaller mates. Because some female wolves were <27.5 kg and closer in body size to coyotes and hybrids than male wolves were, they were more capable of reconciling the costs of having smaller coyote or hybrid mates than males were. With regards to strategies for red wolf recovery, assortative mating can be managed simultaneously with other population-level processes (i.e., births, deaths, immigration, emigration). Strategies to mitigate human-caused mortality and increase population size and pack structure would ultimately increase positive assortative mating between red wolves and coyotes.

Canid population genetics

I pursue research questions pertaining to processes that generate, maintain, and direct genetic variation in canid populations through collaborations with other research programs focused on genetic research. Two important collaborations have been with the NACAP led by Dr. Bridgett vonHoldt at Princeton University and Dr. Kristin Brezski's Conservation Genetics Lab at Michigan Technological University. My collaborative efforts have produced several publications that identified a contact zone between northeastern and southeastern coyotes [#14], demonstrated that western, northeastern, and southeastern coyotes belong to genetically and morphologically distinct populations [#16, 20], reported the occurrence of genes associated with dispersal in eastern coyotes [#16], proposed the hypothesis that eastern coyotes are larger than their western counterparts because selection pressure on the colonization range favored larger animals with greater dispersal capabilities [#20], and rediscovered red wolf alleles in a canid population on Galveston Island, Texas [#19].

Photo credits: Kathrin McClean (top header); Joey Hinton (all other photos)