Bobcat Hair Cortisol Correlates with Land Use and Climate

Abstract

Bobcats (Lynx rufus) have been increasing in abundance in the northeast United States despite a corresponding trend of increased anthropogenic land uses. Inhabiting areas of high human land use can affect stress levels, and hence cortisol titers, for wildlife species by increasing frequency of human interaction and altering habitats. In turn, increased cortisol levels can have negative effects at the individual and population level including decreased immune function, slowed growth and tissue repair, reduced reproductive capacity, and nutritional deficiencies. We quantified cortisol in bobcats across New Hampshire and Vermont, USA, using hair samples, then explored associations between hair cortisol and various organismal, land use, land cover, and climatic variables at 2 different spatial scales. Hair cortisol differed by season and bobcat mass. On average, cortisol levels were higher in fall than in spring, and larger bobcats had lower cortisol levels. Anthropogenic land uses-especially residential and agricultural uses-were the most important predictors of hair cortisol at the town scale ( ̅x area = 93 km 2 ). At a larger scale (Wildlife Management Units; ̅x area = 1,256 km 2 ), temperature and precipitation were better predictors of hair cortisol, suggesting that extreme weather may have significant effects on bobcat population dynamics. Our results highlight the importance of landscape composition and local conditions in the sustainable management of furbearer populations.

A human-neutral large carnivore? No patterns in the body mass of gray wolves across a gradient of anthropization

“…In some cases, anthropized environments are sub-optimal, due to decreased prey availability [ 5 ] the influence of human activity and artificial nightlight on foraging [ 6 , 7 ], persistent human disturbance [ 8 ], the impact of infrastructures on population connectivity and mortality [ 9 , 10 ], disease transmission and competition with domestic dogs [ 11 ] and the risk of accidental intoxication [ 12 ]. These dynamics can in turn raise metabolic stress [ 13 ], and limit reproduction and survival, thus creating source-sink dynamics with undisturbed areas [ 14 ].…”

“…Finally, on some other cases, effects are non-linear: moderate levels of anthropization seem to be advantageous [ 22 ], or detrimental [ 13 ], compared to natural environments, but these effects reverse as anthropization increases.…”

A human-neutral large carnivore? No patterns in the body mass of gray wolves (Canis lupus) across a gradient of anthropization

“…In some cases, anthropized environments are sub-optimal, compared to natural ones, due to decreased prey availability [5] , the influence of human activity and artificial nightlight on foraging [6] [7] , persistent human disturbance [8] , the impact of infrastructures on population connectivity and mortality [9] [10] , disease transmission and competition with domestic dogs [11] and the risk of accidental intoxication [12] . These dynamics can in turn raise metabolic stress [13] , and limit reproduction and survival, thus creating source-sink dynamics with undisturbed areas [14] .…”