ANNUAL VARIATION IN HABITAT SELECTION - PATTERNS CONCEALED BY POOLED DATA

I reviewed 43 papers published in The Journal of Wildlife Management ( JWM, 1988-91) that examined habitat selection of terrestrial vertebrat es by comparing habitat use with availability. My objective was to det ermine whether annual variation in habitat selection was typically con sidered in these studies. Most studies (84%) recognized the potential for variation in habitat selection on a seasonal scale, by either rest ricting investigations to one season or analyzing data separately for individual seasons. In contrast, 72% of the 39 studies that spanned >1 year pooled data on habitat use among years, evidently without testin g for annual variation and without presenting use data for individual years. Most studies (56% of 43) lasted 2 years. I present an example f or female black bears (Ursus americanus) that illustrates the misleadi ng inferences that can result from pooling data among years. The value of most selection studies is limited by their short duration and by t he common approach of assuming resource use is static on an annual sca le.