|Abstract or Summary
- Population attributes, behavior, and activity patterns of
Nuttall's cottontails (Sylvilagus nuttallii) inhabiting a
juniper-sagebrush scabland community in central Oregon were studied
between June 1980 and August 1981. Cottontails were trapped, marked
for individual recognition, and released at their sites of capture.
Data collected by periodic trapping and censusing of cottontails on
the study area indicated that population densities, and rates of
natality and survival of cottontails were similar to those that
occurred during the preceeding 8 years on the same area.
Behavioral and environmental data were collected during systematic
observation periods conducted on a selected portion of the study
area, and during cruises that covered the entire 116-ha study area.
Postures, body movements, and behaviors exhibited by Nuttall's
cottontails were cataloged and compared with those reported for other
leporids. Observed behaviors were classified into the following
categories: feed, rest, locomote, groom, tree-climbing activities,
interspecific interactions, transitional acts, coprophagy,
vocalizations, reproductive social interactions, and nonreproductive social interactions. Of 1,192 behavioral acts recorded during 352 h of
systematic observation, 92.9% represented nonsocial behaviors and
accounted for 92.6% of the total time cottontails were in view.
Behavior of cottontails appeared to be directed towards maintenance of
favorable energy balance; when in view during daytime hours,
cottontails spent most of their time feeding (58.5%) and resting
(23.0%). Nuttall's cottontails were observed to climb in juniper
trees, and this behavior was believed to be an adaptation for
acquiring water in times of moisture stress. Adult social behavior
was observed only during the reproductive season, and accounted for a
relatively small portion (7.4%) of the activity budget of cottontails.
Indices of cottontail activity were examined in relation to
reproductive condition of cottontails collected near the study area
and to environmental conditions at the time of observation.
Correlation coefficients and principal component analysis suggested
the absence of a single dominating environmental influence on
cottontail activity patterns. Seasonal variation in activity of adult
cottontails, particularly males, was related to reproductive
condition; activity increased from the second through fourth breeding
periods then declined during the last breeding period within the
reproductive season. A dramatic decline in activity of adult males
corresponded with regression of testes among cottontails collected
nearby and with cessation of breeding.
Nuttall's cottontails exhibited a bimodal pattern of daily
activity that appeared related to temperature and moisture requirements of rabbits and combinations of environmental constraints
that influenced those requirements. An early morning peak of activity
corresponded with increasing ambient temperatures and near-maximum
plant water content; activity reached a low point during midday, when
air temperatures often were above the zone of thermoneutrality for
rabbits and water availability was minimal; an evening peak of
activity that corresponded to more favorable air temperatures may be
related largely to metabolic demands for energy.