A TECHNIQUE FOR EVALUATION OF SPATIAL DATA USING ASYMMETRICAL WEIGHTED OVERLAP VALUES

Behavioural analyses often require documentation of spatial overlap of individuals or groups. Most often these data have been presented as u nweighted overlaps, calculated as the percentage of home range area th at is shared between neighbours. This metric does not take into consid eration the frequency of use of space in the area of overlap, which of ten is less than in the core of a home range. A method for calculating asymmetrical weighted overlap values between neighbouring individuals or groups is described using a program written for SAS. This method y ields a null expectation of the likelihood of interaction between neig hbours, by taking into consideration their respective frequency of use of space in the area of overlap. A. comparative analysis of a sample data set is presented using both unweighted and weighted overlap value s. The results indicate that the two methods would generate different null expectations of the frequency of social interactions. The asymmet rical weighted overlap method is a valuable approach for the character ization of the texture of space use by animals and the generation of e xpectations for interaction frequency between neighbours.