Halogenated flame retardants in bobcats from the midwestern United States.

Research techniques in animal ecology: controversies and consequences

Roadways pose challenges for conserving wide-ranging animal species. As bobcat (Lynx rufus) populations recover in Ohio, an accurate evaluation of population metrics is critical to understanding future population trajectories. In this study, we integrated multiple datasets to examine overall road mortality rates in Ohio. First, we utilized a long-term vehicle-strike dataset (1978-2017) to determine landscape and local predictors of road mortality. We found that bobcats were killed at higher rates on interstates regardless of surrounding landscape composition, but that landscape variables were useful at predicting mortality on lower-traffic roads. To explore road avoidance behaviors, we used GPS telemetry data from 18 individuals to compare road crossings along trajectory paths with random road crossings simulated using Correlated Random Walks. Bobcats exhibited avoidance of certain route types (county, municipal, and US routes). Finally, by integrating traffic volume data, road crossing behavior, and accounting for the proportion of each route type present in the study area, we estimated that a minimum of 6% and up to 18% of the bobcat population in Ohio is lost to vehicle-strikes annually. To fully understand the population level impacts of this mortality, we recommend further monitoring of age structure and sex of roadkill animals. Our results identify potential areas for mitigation of vehicle-strikes and emphasize the importance of accounting for road mortality when making management decisions for Ohio's recovering bobcat population.

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Roadkill and space use data predict vehicle-strike hotspots and mortality rates in a recovering bobcat ( Lynx rufus ) population

Carnivores act as top-down regulators in terrestrial ecosystems, and their occurrence and relative abundance is a result of complex interactions between food and habitat availability, human pressure (e.g., trapping, hunting, roadkill) and intraguild interactions (competition, predation). Eastern United States has a long history of human impact, which resulted in an altered carnivore community. Specifically, Ohio presents an interesting case for evaluating the relative roles of interspecific relations and habitat characteristics for shaping the carnivore community, as its carnivore community has a unique dynamics and composition: invasive coyote and red fox (Vulpes vulpes), and native bobcat (Lynx rufus), currently recovering and expanding its range, gray fox (Urocyon cinereoargenteus) declining at a fast pace, and the generalist raccoon (Procyon lotor) and Virginian opossum (Didelphis virginiana). We used 50 camera traps to collect presence/absence data in southeastern Ohio, USA. We hypothesized potential interactions between the six carnivores, and used land cover variables, as well as occupancy probabilities of interacting species, to parameterize to single-species occupancy models. We found that landscape composition at three different scales (500m and 1000 m buffer around camera locations, and 3x3 km grid cell) had little effect on species occurrence. We identified strong negative interspecific relations between carnivores, with bobcat occurrence being influenced by presence of coyotes, red fox occurrence by gray foxes, and raccoon occurrence by Virginia possums. While these findings cannot discriminate between habitat partitioning (spatial or temporal) and competition (direct or interference), they lend support to complex dynamics between invasive coyotes and red foxes and recovering (bobcat) and declining (gray fox) native carnivore species. In particular, the negative relation between the apex predator in our system, C. latrans, and L. rufus, raise further questions on whether direct competition from coyotes has the potential to slow bobcat population recovery. In the context of regulated trapping (ongoing for gray fox and proposed season for bobcat), a better understanding of the carnivore intraguild relations can inform management and conservation actions targeted at minimizing the impact of competition on at-risk native species from non-native species.

Relative Importance of Habitat Characteristics and Interspecific Relations in Determining Terrestrial Carnivore Occurrence

Bobcat Population Ecology in West Virginia Stephanie Michelle Landry Bobcats (Lynx rufus) are a popular furbearer and game species throughout their range in North America, where they serve as a top predator in many of their ecosystems. However, bobcat populations across their range declined during the 1800s and early 1900s due to overharvest. Overharvest and habitat loss in Europe also affected the Iberian lynx (L. pardinus), resulting in the listing of all Lynx spp. under the Convention on International Trade in Endangered Species in 1977. Bobcats were listed under Appendix II, which required that state management agencies monitor their bobcat populations for stability. Since their listing, bobcat populations have experienced a large-scale increase in abundance in most areas of their range, partly due to the conversion of agricultural lands to early successional forests that supported ample prey populations during the mid-20 century. However, as forests in West Virginia mature, their common, early-successional prey species, such as rabbits and small rodents, may experience population declines. Availability of small mammal populations during winter is an important factor for survival of juvenile bobcats. Bobcats are harvested annually for their pelts in West Virginia, where the bobcat harvest season runs from November – February with a 3-bobcat limit per licensed person per season. West Virginia’s bobcat population has not been studied since the late 1970s when there was no annual harvest limit enacted on the population. Therefore, current estimates and demographic data are needed before making further management decisions for the bobcat population. We collected 524 bobcat carcasses from hunters and trappers across West Virginia over 2 harvest seasons (i.e., 2014–2015, 2015–2016) to determine current demographic data, such as age structure, sex ratio, reproductive rates, and survival, which are used to determine population change rates for bobcats under current state harvest regulations. We also subsampled 300 bobcats for stomach contents to determine current winter dietary habits. Proportion and diversity of prey items selected by bobcats is often correlated with prey abundances and habitat quality, which can allude to dietary availability for bobcats over winter. We found that bobcats in West Virginia have an even sex ratio and are predominately adults >2 years old (50%), followed by yearlings (1–2 yr; 30%) and juveniles (<1 yr; 20%). Reproductively active females (>1 yr) averaged 1.54 kittens/female annually, with young born from mid-April to mid-August. Mean juvenile survival over both harvest seasons was 0.82, while mean yearling survival was 0.77 and mean adult survival was 0.61 over both harvest seasons. Rate of population change was +44% after the first harvest season and remained stable after the second. White-tailed deer (Odocoileus virginianus), Virginia opossum (Didelphis virginiana), and raccoon (Procyon lotor) occurred more frequently in the diets of male bobcats, whereas lagomorphs occurred more frequently in females. Small and medium-sized rodents, such as squirrel, mice, and chipmunks (Tamias spp.), occurred more frequently in the diets of juveniles than yearling and adults, whereas white-tailed deer occurred more frequently in adults than juveniles and yearlings. There was 92% overlap in overall dietary selection between sexes and 35% overlap between stage classes, with an 87% diversity in prey selection overall. Managers can use these data to determine proper harvest limits and to enact necessary habitat manipulations to support management goals for bobcats in West Virginia.

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Bobcat Population Ecology in West Virginia

Bobcats (Lynx rufus) are a native carnivore of Ohio, but by 1850 were extirpated or nearly so following pioneer settlement of the state. The first modern record of a bobcat in Ohio was an adult male killed in 1946. Distribution accounts indicate that population re- establishment began around 2000. Today the bobcat is protected, and verified sightings, camera surveys, and genetic analyses point to two subpopulations: a fast growing, self-sustaining eastern subpopulation, and a more slowly growing southern subpopulation. We evaluated stomach contents of 120 adult and subadult bobcat carcasses to help understand the disparity in subpopulation growth rates, and inform proper bobcat management. We identified prey species morphologically. We quantified prey species taken and converted their frequencies to caloric intake estimates. We calculated dry weight estimates of prey groups and compared them between bobcat age classes, sexes, regions, and across seasons. We examined regional diet differences furt...

https://bioone.org/journals/The-American-Midland-Naturalist/volume-173/issue-2/amid-173-02-305-317.1/Diet-of-the-Recovering-Ohio-Bobcat-Lynx-rufus-with-a/10.1674/amid-173-02-305-317.1.pdf

Diet of the Recovering Ohio Bobcat (Lynx rufus) with a Consideration of Two Subpopulations

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Christa Rose

Papers

Roadkill and space use data predict vehicle-strike hotspots and mortality rates in a recovering bobcat ( Lynx rufus ) population

Diet of the Recovering Ohio Bobcat (Lynx rufus) with a Consideration of Two Subpopulations

Author Correction: Roadkill and space use data predict vehicle-strike hotspots and mortality rates in a recovering bobcat (Lynx rufus) population.