Geoscience Reference
In-Depth Information
mation obtained from such samples. Steroid concentrations (especially estro-
gen) have been used to examine pregnancy rates among free-ranging mammals
(Kirkpatrick et al. 1990). This technique could be modified to distinguish
male- and female-derived fecal samples. Even greater sample resolution is pos-
sible by using emerging molecular techniques. As indicated earlier, fecal sam-
ples contain epithelial cells shed from the intestine walls of the animal deposit-
ing the sample. DNA extracted from these cells has been used to identify the
species that deposited the sample. Recently, several investigators have used this
approach to identify sex and individual genetic markers (Kohn and Wayne
1997; Reed et al. 1997). Therefore, it is possible to substantially increase the
resolution of fecal samples so that researchers can track the diet of identified
free-ranging individuals. The information obtained from fecal samples could
be enhanced even more by using digestibility correction factors that estimate
biomass consumed. The resulting data set would probably prove very useful in
evaluating diet selection and effects of consumption patterns on the forage or
prey community.
As should be apparent by now, substantial information on food use patterns
of vertebrates has been collected. Yet the ability of biologists to apply this infor-
mation to understand factors that affect an organism's fitness or role in com-
munity structure has been limited. Perhaps the most needed change is to ensure
that future investigations have a more complete context associated with them.
Rather than partitioning studies into separate efforts to examine food and habi-
tat use, these investigations should occur (and be reported) simultaneously.
Recent advances in molecular biology will enable vertebrate ecologists to
generate a more complete picture of food use patterns by specific segments of
a population. Such detailed information will enhance our ability to under-
stand community relationships and spatialemporal patterns of vertebrate
abundance. Rather than addressing general questions on the natural history of
a specific species or population, clearly defined investigations of animal food
habits may enhance our ability to answer the important how and why ques-
tions of vertebrate ecology.
Literature Cited
Ackerman, B. B., F. G. Lindzey, and T. P. Hemker. 1984. Cougar food habits in southern
Utah.
Journal of Wildlife Management
48: 147-155.
Adorjan, A. A. and G. B. Kolenosky. 1969.
A manual for the identification of hairs of selected
Ontario mammals.
Ontario Department of Lands and Forests, Research Report
(Wildlife) no. 90.
