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Assessing habitat selection when availability changes

Ecology

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Abstract

We present a method of comparing data on habitat use and availability that allows availability to differ among observations. This method is applicable when habitats change over time and when animals are unable to move throughout a predetermined study area between observations. We used maximum-likelihood techniques to derive an index that estimates the probability that each habitat type would be used if all were equally available. We also demonstrate how these indices can be used to compare relative use of available habitats, assign them ranks, and assess statistical differences between pairs of indices. The set of these indices for all habitats can be compared between groups of animals that represent different seasons, sex or age classes, or experimental treatments. This method allows quantitative comparisons among types and is not affected by arbitrary decisions about which habitats to include in the study. We provide an example by comparing the availability of four categories of sea ice concentration to their use by adult female polar bears, whose movements were monitored by satellite radio tracking in the Bering and Chukchi Seas during 1990. Use of ice categories by bears was nonrandom, and the pattern of use differed between spring and late summer seasons.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Assessing habitat selection when availability changes
Series title:
Ecology
Volume
77
Issue:
1
Year Published:
1996
Language:
English
Contributing office(s):
Alaska Biological Science Center
Description:
pp. 215-227
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
215
Last page:
227
Number of Pages:
13