Allen, M. L. | bioRxiv Science

bioRxiv2020

Estimating bobcat (Lynx rufus) abundance in Wisconsin during 1981-2015

Quantifying and estimating trends in wildlife abundance is critical for their management and conservation. Harvest-based indices are often used as a surrogate index for wildlife population. Sex-Age-Kill (SAK) models generally use the age-at-harvest of males and females, combined with annual mortality and reproduction rates to calculate a preharvest population estimate. We used and SAK model to estimate abundance for bobcats from 1981-2015. Pre-hunt population size ranged from approximately 1630-2148 during 1981-1995 after which the population increased to a maximum of 4439 in 2005 before declining to 2598 in 2013. Pre-hunt population size was highly correlated an index of abundance from winter track counts (r = 0.93). We found that the model, as currently implemented by WNDR, appears to provide an accurate trend of statewide bobcat abundance. SAK models more logistically feasible for long-term evaluations of population trends overbroad spatial extents than more intensive methods. While SAK models may be the only technique available to wildlife managers for estimating the abundance of harvested species, we encourage additional research to evaluate the effects of potential biases on estimates of abundance.

ecology↗

bioRxiv2020

Mesopredators display behaviourally plastic responses to dominant competitors when scavenging and communicating

Mesopredators face interspecific competition and intraguild predation when sharing resources with apex predators or more dominant mesopredators. We theorize that mesopredators use a variety of tactics to avoid competitively dominant predators at shared locations, such as scavenging and communication sites, that provide a mix of risks and rewards to these smaller predators. We examined whether mesopredator species employed behavioural tactics to reduce risks from dominant pumas when exploiting resources. We monitored carcasses in the Santa Cruz Mountains, CA across a gradient of human development and treated half of the carcasses with puma sign. Bobcats visited treated carcasses significantly later and for less time. Contrary to our expectations, coyotes and grey foxes were more likely to visit treated carcasses, although foxes were significantly less likely to visit a carcass also used by coyotes. Bobcats and foxes were less likely to visit carcasses at higher development levels whereas raccoons exhibited the opposite pattern. At communication sites, we observed temporal segregation among mesopredators and pumas. Coyotes and small predators exhibited the most segregation, followed by coyotes and pumas, and raccoons and pumas. Our results suggest subordinate predators employ a combination of spatial and temporal avoidance to minimize competitive interactions at shared sites.

ecology↗