UNDERSTANDING BOBCATS IN THE GRANITE STATE: A cooperative project led by the University of New Hampshire and the New Hampshire Fish & Game Department

 

What we know about New Hampshire’s bobcats

Historic distribution
Early accounts of bobcats in New Hampshire are quite limited, but there is enough information to suggest that their abundance and distribution has changed substantially during the past 400 years. Back in 1925, Ernest Thompson Seton published a book on furbearers that included a range map of bobcats at the time Europeans first colonized eastern North America. Seton speculated that bobcats only occurred in southwestern New Hampshire at that time and that their range in New England expanded north and east as forests were cleared for subsistence agriculture by settlers.

The map on the right by Seton (1925) shows the distribution of bobcats in the northeastern United States at the time Columbus arrived. The arrows show how the range expanded north and east as forests were cleared.

Years later, Clark Stevens, a member of the Forestry faculty at UNH, was able to piece together a more detailed account of bobcats using the published histories that many towns prepared to document the experiences of early settlers. Stevens found that in the early 1800s, “wild cats” were considered fairly common but later in that century they became scarce. Wild cats was a term used to describe both bobcats and Canada lynx, but most accounts were about bobcats. These general impressions were fleshed out with bobcat bounty records kept by individual towns and eventually by the State (see the Management History section for more information on this). We summarized the bounty claims by township that were made from 1931 to 1965 and found that the southwestern portion of the state seemed to be the core, with populations extending north along the Connecticut River Valley. Central and southeastern New Hampshire supported fewer bobcats during that period.

Bobcats harvested by county 1931-1965

This map summarizes the number of bobcats submitted for bounty payment by township from 1931 to 1965 (for a larger view, click on the map).

What do bobcats eat?
Once again we benefited from the work of Clark Stevens. Clark did a complete examination of many of the bobcats that were submitted for bounty payment from 1951 through 1962. Based on the stomach contents of almost 400 animals, we get a good idea of what bobcats ate back then. Frequently consumed animals included cottontail rabbits (found in 27% of the stomachs), deer (22%), snowshoe hares (22%), gray squirrels (19%), and a variety of mice, voles and shrews (12%). Porcupines, red squirrels, and birds also were eaten but less often.

drwaing of bobcats eatingImage courtesy of Paul Rego

We took a closer look at Clark’s data and were able to examine prey use by the age and sex of bobcats. These comparisons revealed some interesting patterns. By the time they are two years old, male bobcats are consistently larger than females. Mature males can weigh over 30 pounds, whereas mature females are usually close to 20 pounds. Because of this size difference, males can be effective at capturing large prey, including deer. Juveniles (males and females) and adult females because of their smaller size must rely on small prey, especially rabbits and gray squirrels.

This difference in the ability to capture large prey may explain why juveniles in particular end up in some surprising locations when deep snows limit access to small prey. Extended periods of deep, loose snow are probably tough on adult females as well.

We then compared how bobcat diets have changed with time using Clark’s data and additional information on stomach contents from the late 1970s and early 1980s, we found an obvious change in the use of all major prey. These changes are likely a response to the change in land uses, especially the decline of agricultural fields and meadows.

These graphs summarize the change in food habits among New Hampshire bobcats from 1950s to the early 1980s. Most notable are the changes in consumption of deer, cottontail rabbits, and small mammals (for a larger view, click on the graph).

They come in two colors!
Like most mammals living in the northern regions, New Hampshire bobcats have distinct summer and winter pelages. Coats in summer tend to be tawny brown with obvious areas of red. In winter, the thicker coats lean toward slate gray. There has been some speculation as to what advantage these two colors may bestow on bobcats. Some speculate that the brown coat may be more useful in concealing bobcats among forest litter. On the other hand, the gray coat of winter may capture more heat for the sun’s rays. Although these explanations seem reasonable, there are likely a number of factors influencing coat color.

The two color phases may persist throughout the year to some degree. These two bobcats were harvested during the same month. Photo courtesy Clark Stevens, circa 1953.

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bobcat harvest by county Graph of food habits