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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.
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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.
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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.
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Image
courtesy of Paul Rego
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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.
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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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