As a practical matter, it is much easier to study the behavioral processes responsible for habitat selection at smaller than at larger spatial scales. Many species will express reasonably natural microhabitat selection behavior under controlled conditions in the laboratory or in field enclosures, so we know quite a bit about how animals select foraging sites, oviposition sites, shelter sites, etc. However, it is much more challenging to design and conduct elegant experiments of habitat selection at larger spatial scales. As a result, researchers interested in habitat selection at the level of individuals and populations often estimate habitat selection indirectly, by comparing the habitat features of areas actually used by individuals or groups of individuals with habitat features at points in the same region that have been randomly chosen by the researcher. The implicit assumption here is that any difference between the two distributions reflects active habitat choice by the individuals in that population. However, this assumption is often problematical. For instance, the habitat-use patterns of new recruits in marine fish and invertebrates are strongly affected by habitat-specific mortality immediately after settlement. As a result, nonrandom distributions of new recruits across the landscape often have more to do with differential mortality than they do with differential settlement, or movement by new arrivals to preferred habitats.
Several authors have suggested using the term 'habitat use' rather than 'habitat selection' to refer to nonrandom spatial distributions of animals and other mobile organisms in heterogeneous landscapes. Habitat use carries no implicit assumptions about the processes which are responsible for associations between organisms and particular habitat features, and instead simply indicates habitat features which are associated with the space-use patterns of the organism of interest. As was indicated earlier in this article, identifying the factors which are associated with the habitat-use patterns of a given organism is an important first step toward identifying the factors that are required to support individuals and populations of any given organism.
See also: Habitat Selection and Habitat Suitability Preferences.
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