Sex-specific differences in space use of Forster's terns (Sterna forsteri) breeding in the South San Francisco Bay, California

Author

Jill Bluso

Graduation Date

2007

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Natural Resources: Wildlife, Humboldt State University, 2007

Committee Chair Name

Mark A. Colwell

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Humboldt State University -- Theses -- Wildlife, Space use, Radio telemetry, Breeding stage, San Francisco Bay, Forster's tern, Sex differences

Abstract

In seabirds, sex-specific parental care during reproduction can lead to sex-specific differences in foraging location, behavior, and use of foraging areas. Sex-specific differences in location and use of foraging areas have been well documented among dimorphic species, however research on sexually monomorphic seabirds has been limited. I studied Forster's terns (Sterna forsteri), a monomorphic and socially monogamous seabird, in the South San Francisco Bay, California to examine sex-specific differences in the distance from the nest, the foraging range, and the home-range and core-area size of terns. Space use by Forster's terns did not differ between the sexes; however, all measures of space use varied significantly by breeding stage, and to some degree, by colony affiliation. Forster's terns were located farthest from the nest during pre-breeding and post-breeding stages, and found closest to the nest during incubation and chick-rearing stages. Home-range and core-area size significantly decreased as the breeding season progressed and was most concentrated in the post-breeding stage. The foraging range of Forster's terns differed significantly between colony sites. This is the first study of a monomorphic seabird that did not document sex-specific differences in space use, however, sex-specific differences may exist on a finer spatial scale than investigated in this study.

https://scholarworks.calstate.edu/concern/theses/fj236445c

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