Geoscience Reference
In-Depth Information
Figure 4.1
Hypothetical movements of an animal overlaid on five (numbered) habitat types. Habi-
tat selection is often assessed in terms of relative use compared to availability. In this example, habi-
tats 1, 3, and 4 were used and thus also available. Habitat 2 (depicted as a swamp) appears to have
been traversed, possibly just to get from habitat 1 to habitat 3; if it was used simply because of its
location, not because of its habitat-related attributes, a question arises as to whether it should be
considered in the analysis. Conversely, although habitat 5 was not used, it may or may not be con-
sidered available. Judged within the context of the home range boundaries, point A in habitat 5
appears to be unavailable, yet this point is closer to known locations of the animal than points B or
C, which are both within the apparent home range. Habitat availability is a nebulous concept, and
thus may be difficult to measure. Similarly, although the figure depicts a travel route, from which rel-
ative use of habitats might be deduced, most analyses deal with relative time, not distance, in each
habitat (partly because telemetry data are generally comprised of point locations); it is unclear which
is really a better measure of use.
