Mathot, Kimberley J. 2005. Sex-related differences in feeding behaviour and
implications for differential migration in Western Sandpipers (Calidris mauri). MSc
thesis. Centre for Wildlife Ecology, Department of Biological Sciences, Simon Fraser
University, Burnaby, BC.
I examined relationships between bill morphology, feeding behaviour and non-breeding
distribution in a sexually dimorphic shorebird, the western sandpiper (Calidris mauri).
The sexes are differentially distributed across the non-breeding range, with males, the
shorter-billed sex, shifted north relative to females. Males are more reliant on epifaunal
(surface) feeding during both migration and the non-breeding period while females do
more infaunal (sub-surface) feeding. I tested whether differences in feeding mode result
in sex-related differences in diet. Results of surficial food removal plots and stable
isotope analyses were equivocal. I also tested the hypothesis that latitudinal gradients in
the vertical distribution of food (invertebrates and biofilm) underlie differential migration
in western sandpipers. Epifaunal food dominated at northern sites, while infaunal food
dominated at southern sites. This study is the first to relate latitudinal scale changes in
the distribution of food to functional morphology and differential non-breeding
distribution in a shorebird.