Survival of cougars caught in non‐target foothold traps and snares

Abstract

Cougars (Puma concolor) occupy mountain ranges throughout the Great Basin, Nevada, USA, where legal trapping of bobcats (Lynx rufus) is common and some non‐target captures of cougars in bobcat traps occur. Such incidental capture of cougars is an undocumented source of mortality because some cougars die from injuries several weeks after release from traps. We examined cause‐specific mortality and the effects of capture of cougars in bobcat traps on annual and overall (7‐year) survival during 2009–2015. We captured 48 cougars, of which we followed 33 until death. We estimated average annual survival rates for adult cougars and assessed the relative effects of sex, season, and long‐term effects of non‐target capture of cougars in foothold traps on estimated survival of adults using a nest survival model in Program MARK. We incorporated a time‐varying covariate to assess the long‐term effect of capture in non‐target foothold traps on survival of adult cougars. Average annual survival of non‐trapped females and males, regardless of trapping history, was significantly greater than females with a history of capture in a non‐target foothold trap; however, once partitioned across age, sex, and capture status, sample sizes were small. Our results suggest that capture in non‐target foothold traps decreases survival of adult female cougars directly by causing injuries that eventually result in mortality, and indirectly by increasing susceptibility to other forms of mortality. Mortality of adult females during the 7 years of our study caused by non‐target trapping was similar to hunting among radio‐marked female cougars, and this potential source of mortality has been unaccounted for in harvest objectives and harvest data for cougars without radio‐collars. Given anthropogenic sources of mortality accounted for 100% of recorded mortality of adult females, mortality from non‐target trapping is likely additive to other sources of mortality in our study area. We recommend regulatory agencies consider the possibility of unintentional take and potential for reduced long‐term survival of females where these large fields are sympatric with bobcats, and trapping of bobcats with foothold traps is a legal activity. Moreover, we suggest wildlife managers record information about the trapping incident, to include trap type, trap size, trap set type, location, number of days since last check, and type and severity of injuries when releasing incidentally captured cougars to inform future management decisions. Addressing other anthropogenic sources of mortality resulting from conflict with humans and road mortalities will be increasingly important as the human population expands into cougar habitat. © 2018 The Wildlife Society.

Recolonizing carnivores: Is cougar predation behaviorally mediated by bears?

“…We monitored 31 GPS‐collared cougars in Nevada between 2009–2012 and 2015–2017. Cougars were captured, chemically immobilized, and fitted with global positioning system (GPS) collars (Globalstar collars by Vectronic Aerospace GmbH, Berlin, Germany; North Star Science and Technology, King George, Virginia, USA), following approved handling and capture techniques described in Andreasen et al., (2018; State of Nevada scientific collection permit #S33313 and University of Nevada, Reno Animal Care Protocol #A06/07‐28). The GPS collars were programmed to collect geographic coordinates at intervals ranging from 2.5 to 5 hr.…”

“…The GPS collars were programmed to collect geographic coordinates at intervals ranging from 2.5 to 5 hr. The focal study sites were located in the far western edge of the Great Basin and the eastern Sierra Nevada across several mountain ranges (Andreasen et al., 2018; Figure 1). Available prey in the Sierra Nevada consists primarily of mule deer and nonungulate mammals.…”

“…North Star Science and Technology, King George, Virginia, USA), following approved handling and capture techniques described in Andreasen et al, (2018; State of Nevada scientific collection permit #S33313 and University of Nevada, Reno Animal Care Protocol #A06/07-28). The GPS collars were programmed to collect geographic coordinates at intervals ranging from 2.5 to 5 hr.…”

Prey Specialization by Cougars on Feral Horses in a Desert Environment

“…We followed procedures outlined in the capture permit (State of Nevada scientific collection permit S33313) issued by the Nevada Department of Wildlife (NDOW). Andreasen et al (2018) provide further details on animal capture. We defined a potential kill using GPS clusters, defined as ≥2 GPS location points within 200 m, including ≥1 night location Lindzey 2003, Knopff et al 2009).…”

“…Urban, exurban, and residential developments along the wildland-urban interface in the study area include Reno, Carson City, Dayton, Minden, and Gardnerville, and the study area has one of the fastest growing human populations in the United States (Northern Nevada Economic Planning Indicators Committee 2015). Much of this new development is in exurban areas occurring in valley bottoms and foothills, both of which are important winter habitat components for mule deer (Andreasen et al 2018).…”