Geoscience Reference
In-Depth Information
Figure 3.7
Core area and home range for an adult female bear. The core is shown with flat-topped
symbols, the periphery with triangular symbols.
This criterion for a home range core clearly identifies the most intensively
used areas within an animal's home range, and it allows the data (i.e., the ani-
mal) to decide where the boundary between core and periphery should be
located. The criterion is objective and, for me, intuitive (figure 3.7; Powell et
al. 1997; Seaman and Powell 1990). By this objective, each animal's core, if it
has one, is at a different probability of use. In addition, some animals have
large cores and some have small cores.
Quantifying Home Range Overlap and Territoriality
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Home ranges of conspecifics often overlap, sometimes extensively. For a pop-
ulation, hypotheses can be tested regarding simultaneous use of areas of home
range overlap. Subsets of a population may exhibit different patterns of simul-
taneous use. Relatives, for example, may use their areas of overlap more than
expected from random use, whereas nonrelatives may avoid each other and use
areas of overlap less than expected. Intrasexually territorial animals may spend
less time in their areas of overlap with members of the opposite sex than
expected.
For some species, territorial behavior has been documented objectively.
Extensive experimentation with limiting resources and territorial displays and
