bobcat in a small tunnel
Bob Child/AP
Cats in Crisis
Is increased proximity to humans stressing New Hampshire’s bobcat population?

s the biological analog of UNH’s wildcat mascot, the bobcat holds a special place in the heart of many UNH students and alumni. But a recent study published in the Journal of Wildlife Management suggests the feeling might not be particularly mutual.

Researchers with the College of Life Sciences and Agriculture and the New Hampshire Agricultural Experiment Station have documented elevated cortisol levels in hairs taken from bobcats living closer to residential and agricultural areas. A hormone found in all mammal species — humans included — cortisol plays an important role in stress response. Higher levels of cortisol in hair samples are indicative of higher levels of the hormone circulating in the cats’ bloodstream, released in response to increased levels of stress.

“Under normal conditions, cortisol helps our bodies regulate energy and gives us the resources needed to deal with the stressful situation. This is a good thing for our bodies — we deal with the situation then return to normal,” explains wildlife ecologist Rory Carroll, an assistant professor of biology at Southern Arkansas University. “However, chronically high cortisol levels can worsen individual bobcats’ health and lower reproduction rates of populations.” Carroll conducted his research as part of his doctoral studies at UNH, working with Marian K. Litvaitis, professor emerita of natural resources and the environment, and Thomas Foxall, professor of biological sciences.

Carroll and his UNH collaborators found that male and female bobcats had different responses to the landscape, but for both sexes, animals located where a greater proportion of land use was residential and agricultural had higher cortisol levels. In general, larger bobcats had lower cortisol levels, and cortisol in all bobcats was lower in the spring than in the fall. Below-average temperatures in the fall related to lower cortisol levels as well.

According to New Hampshire Fish and Game and UNH researchers, New Hampshire has approximately 1,400 bobcats. Small predators such as bobcats and coyotes are the top “apex” predators in the region. As such, they have a large impact on the state’s forest ecosystems, helping sustain balanced wildlife communities of smaller mammals such as rodents, rabbits, and groundhogs that can carry diseases and disrupt production on commercial farms and backyard gardens.

“Populations are always changing, and we want to understand what has caused some pretty dramatic rises and falls over the decades,” says Carroll. “Bobcats are currently abundant across the region despite a huge human influence on the landscape. Knowledge on how they are learning to live alongside humans will ultimately help us be better and more responsible neighbors of our wildlife species and target conservation efforts in critical areas to sustain healthy populations of bobcats.”

—Lori Tyler Gula PhD, ’06G, ’19G