Recipient Organization
UNIVERSITY OF WASHINGTON
4333 BROOKLYN AVE NE
SEATTLE,WA 98195
Performing Department
Wildlife Science
Non Technical Summary
Large carnivores are key components of ecosystems, but the ability of scientists to predict their cascading effects remains alarmingly poor. Large carnivores may suppress mesopredators through direct killing, resource competition, and behavioral effects. However, large carnivores may also facilitate mesopredators by providing resource subsidies in the form of carrion. Interactions among carnivores may therefore range from facilitation to suppression, but a framework to predict the strength and direction of these intraguild interactions is currently lacking. This project develops a new conceptual framework that will be tested using an intensive field study of carnivores and their resources. The PI will examine mesopredator ecology in northeastern Washington, where collaborators are initiating a major new study of wolves, cougars, deer, elk, and moose. A powerful combination of animal-borne GPS and video tracking technology, stable isotope enrichment of carcasses, fecal genotyping, and cameras at kill sites will be used to jointly examine facilitation and suppression.A recent study conducted by the PI in Alaska has fueled new hypotheses that will be tested in Washington. In Alaska, mesopredators positively associated with wolves at a local scale, but wolves suppressed mesopredators at a landscape scale. These contrasting scale-dependent patterns were strongest for mesopredators that often scavenged, raising the possibility that kill sites present a "fatal attraction" leading to landscape-scale suppression of subordinate mesopredators.This study will provide opportunities to involve Alaska Native students in field and lab research, and cameras at kill sites will be used to create authentic research experiences for a diverse group of undergraduate students through a major course redesign. The integration of research and teaching will benefit the PI's research program by fostering hypothesis testing and data processing on the part of students, while at the same time contributing towards her teaching goal of improving the effectiveness of wildlife science education for a diverse student body.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
This study will form the foundation of my research program by addressing a fundamental unanswered question in community ecology: What factors determine the strength of facilitation and suppression among carnivores? This study will transform our mechanistic understanding of these key interaction pathways using innovative field methods and modeling focused on wolves, cougars (Pumaconcolor), coyotes, and bobcats (Lynx rufus) in Washington. Below, I describe my main hypotheses:H1: Fatal attraction--Scavenging facilitates intraguild suppression. This hypothesis integrates concepts from theories of competition, predation, and risk-sensitive foraging. Competition theory predicts the strength of suppression should be greatest among species pairs with the highest degree of overlap in resource use (MacArthur and Levins 1967, Palomares and Caro 1999). Based on predation theory,encounter rates should also strongly influence the rate of intraguild killing (Holling 1959). Thus, scavenging should increase the risk of intraguild killing by increasing resource overlap between large carnivores and mesopredators, thus providing the motivation for killing, and by increasing encounter rates, thus providing the opportunity. I would therefore expect mesopredators that often scavenge (e.g.,coyotes) to have a higher risk of mortality from large carnivores than mesopredators that rarely scavenge (e.g., bobcats). If scavenging increases the risk of mortality, risk sensitive foraging theory predicts the rate of scavenging should decrease as the availability of less risky prey (e.g., lagomorphs, small mammals) increases. Thus, scavenging activity should be lowest in summer when availability of vulnerable juvenile prey is highest and dominant competitors for carrion (bears) are active, and scavenging activity should be relatively low in areas or years with relatively abundant small mammal prey.H2: Unlinked facilitation and suppression--The probability of intraguild killing is unrelated to scavenging. If scavenging does not facilitate intraguild killing, then mortality risk from large carnivores should be independent of the benefits provided by scavenging at kill sites. Thus, mesopredators that often scavenge should benefit more from the presence of large carnivores than mesopredators that rarely scavenge, assuming similar mortality rates due to random encounters with large carnivores. If scavenging does not increase the risk of mortality, optimal foraging theory predicts that carcasses should always be exploited by scavengers regardless of live prey availability, because carrion is a high-nutrient food source with virtually no handling costs. Large carnivores often revisit carcasses after initial abandonment (Selva et al. 2005), but mortality risk for mesopredators could be minimized through a number of mechanisms. For example, mesopredators may adapt vigilance levels at kill sites to perceived risk, or they could visit kills during times when large carnivores are less active (Switalski 2003, Embar et al. 2011). Revisitation patterns of large carnivores may be predictable, though such patterns have not been assessed.H3: Primacy of phylogeny--Intraguild interactions are strongest within families. Across the Carnivora, intraguild killing tends to be more common between species within the same family (Palomares and Caro 1999). Contrary to predictions of competition theory, the phylogenetic hypothesis predicts that closely related carnivores should interact more than more distantly related carnivores, regardless of niche overlap. Thus, cougars should kill bobcats more often than they kill coyotes, despite having higher diet overlap with coyotes due to their scavenging. Coyotes and bobcats should likewise not interact strongly according to the phylogenetic hypothesis, whereas competition theory would predict frequent killing due to high diet overlap. Because no previous study has radio-collared sympatric large and small carnivores from multiple families simultaneously, the relative importance of diet overlap and phylogeny in mediating intraguild interactions remains unknown.The overarching educational goal of this project is to improve the ability of college graduates to tackle pressing problems in wildlife conservation and management. I have three specific aims: (1) to advance undergraduate science education by integrating authentic research into a large introductory wildlife course, (2) to increase the participation and retention of underrepresented groups, especially Alaska Natives, in wildlife science, and (3) to increase the availability of scientifically-based information about carnivores to K-12 students and the general public.
Project Methods
This study will be conducted in northeastern Washington, where resident cougars, wolves, elk, moose, and deer will be fitted with radio collars by Washington Department of Fish and Wildlife (WDFW) collaborators. Patterns of carcass production, scavenging activity, and mesopredator mortality will be compared before and after wolf presence as well as between areas with and without wolves.Research ApproachA combination of animal-borne GPS and video technology, intensive monitoring and experimental manipulation of carcasses, scat analysis, stable isotope analysis, and modeling will be used to evaluate hypotheses. I will focus detailed studies on effects of wolves and cougars on coyotes and bobcats, while also broadly examining dynamics of the entire scavenging community.Carrion supply. I will quantify the biomass of carrion created by each mechanism using multiple independent methods.Carrion use. Consumption of carrion by all mammalian and avian scavengers will be quantified by monitoring carcasses using cameras and using published relationships between feeding times and biomass consumption for avian and mammalian scavengers (Wilmers et al. 2003a). The importance of carrion in the diet of coyotes and bobcats will be estimated using several methods. Second, carrion energy flow to consumers will be estimated by enriching carcasses with stable isotopes and tracking the unique isotopic enrichment to scavenging carnivores.Risk of mortality at carcass sites. Photos from cameras will be used to estimate (1) communitywide encounter risk for mesopredators at carcasses, (2) risk reduction via temporal partitioning, and (3) how rapidly encounter risk declines over time as the carcass is consumed.Small prey availability. To determine how carrion consumption may vary with the availability of alternative resources, we will estimate the relative abundance of small mammal prey in 10 locations within the home ranges of different coyote and bobcat individuals.Carnivore densities. Densities of coyotes and bobcats will be estimated each year using genotyped scats (Prugh et al. 2005, Efford and Fewster 2013).Effects of large carnivores on the supply of carrion biomass will be modeled by adapting the age-structured predator-prey model developed by Wilmers and Getz (2004) to account for multiple speciesof predators and prey and different forms of density dependence. Comparison of ungulate mortality rates, causes of mortality, cougar kill rates, and carcass consumption rates in areas with and without wolves will be used to parameterize models.Statistical analyses. Spatial capture-recapture (SCR) models will be used to examine the effects of wolves and cougars on coyote and bobcat densities using genotyped scats and GPS locations.Educational ApproachObjective 1: Improve wildlife science education by redesigning an introductory course using inductive teaching methodsI will pilot the redesign of an introductory wildlife course at the University of Washington (UW) using remote camera data from wolf and cougar kill sites to facilitate student-led research projects.Assessment. The goals of the new inquiry-based lab in ESRM 150 are to increase students' (1) interest in the wildlife science, (2) confidence conducting research, and (3) problem-solving abilities. I will collaborate with Dr. Herrenkohl and the UW Office of Educational Assessment (OEA) to evaluate the success of the new lab in achieving these objectives.Objective 2: Increase diversity in the wildlife fieldI will contribute towards increasing the recruitment and retention of diverse undergraduates in wildlife science by: (1) recruiting advanced undergraduate wildlife majors from underrepresented groups to work as peer mentors assisting the TAs in ESRM 150, (2) providing summer research experiences to Alaska Native undergraduates, and (3) highlighting videos produced by the Alaska Native REU students in ESRM 150.Peer mentoring. I hypothesize that mentoring by advanced peers from underrepresented groups in an introductory course will improve the chances that students with similar backgrounds consider majoring in wildlife themselves. Peer mentoring would also provide valuable employment opportunities to advanced minority undergraduates. The mentoring jobs could boost their confidence and scientific skills under a model of tiered mentorship involving myself and the TAs.Summer research opportunities. We will provide summer research experiences for 4 Alaska Native undergraduate students, in partnership with the Alaska Native Science and Engineering Program (ANSEP). I will offer two 3-month internships to ANSEP undergraduate students each summer for the first 2 years of the project.Integration. The experiences of the Alaska Native students will be integrated into ESRM 150 by highlighting excerpts from video blogs they will create during their research experiences (with permission).Assessment. The impact of the peer mentors and video excerpts on recruitment and retention will be assessed using follow-up surveys and interviews with peer mentors and students who took ESRM 150 in 2018 and 2019.Objective 3: K-12 and public outreachEngaging and informing citizens about wildlife research is critical if policy decisions are to be influenced by science. I will partner with Symbio Studios to create educational videos focusing on the research. Videos will be distributed through Houghton Mifflin Harcourt's Science Fusion Program, reaching a projected audience of 2 million K-12 students per year for 5-7 years. Videos will also be available to the general public through a project website and social media (e.g., @LauraPrugh).