Doctoral Dissertations

Date of Award

12-1981

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major Professor

H H Shugart

Committee Members

Darrell C West, Susan E Riechert, Boyd Dearden

Abstract

The concept that structural habitat cues are proximal factors for territory size is explored by examining the intrapopulation variation in territory size among ovenbirds (Seiurus aurocapillus). Initial territory size was determined during the first weeks of the breeding season and variables describing the structure of the vegetation within these territories were measured. Prey abundance within territories was monitored both within and among breeding seasons and correlated with both territory size and habitat structure. Similar data were also collected on areas of the study site not occupied by ovenbirds.

There is a negative correlation between prey abundance and territory size with territory size decreasing as prey abundance per unit area increase. A comparison of prey abundance between territory sites and areas unoccupied by ovenbirds reveals a significant difference in prey abundance per unit area. Linear multiple regression of prey abundance with variables describing the habitat structure of territory sites indicates that differences in habitat structure account for 73 percent of the variation in prey abundance among territories. Analysis also indicates that those features of the habitat which best discriminate between territories and unoccupied sites are the same habitat variables which correlate with variation in prey abundance.

A comparison of territory size with predicted prey abundance on the basis of habitat structure shows territory size is more strongly correlated with habitat structure (i.e. predicted prey abundance) than actual or sampled prey abundance, suggesting the use of habitat structure as a proximal factor for territory size. Those territories which showed the greatest difference between predicted prey abundance on the basis of habitat structure and actual or sampled prey abundance were tested for their fit to the two models: territory size—prey abundance, territory size—habitat structure. Results show that the model defining territory size as a function of habitat structure is significantly correlated with territory size, whereas, territory size was not found to be significantly correlated with actual prey abundance for the territories included in the analysis.

In an analysis of the role of intraspecific competition on territory size, the relationship between territory size and distance to the nearest neighboring territory was analyzed. Results show that the distribution of territories in the study area is not significantly related to either prey abundance or habitat structure and that distance to nearest neighbor accounts for only a small portion of the variation in territory size.

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