4.2 Sex-related dietary specialization
While many previous studies have observed differences in foraging behavior and invertebrate prey selection between sexes in western sandpipers, we report the first observation of differences in biofilm and microphytobenthos consumption between sexes (Fernández & Lank, 2008; Mathot & Elner, 2004; Mathot, Lund, & Elner, 2010; Nebel, 2005). Our results indicated that consumption of microphytobenthos increased and consumption of Polychaeta decreased with decreasing bill length in western sandpipers. We also found that the consumption of other invertebrates – a prey group predominantly composed of epifaunal invertebrates in the classes Malacostraca and Gastropoda – increased with decreasing body mass. Male western sandpipers have shorter bills and lesser mass than their female counterparts which may make males better adapted, both mechanically and energetically, to consume biofilm, microphytobenthos, and invertebrates on the sediment surface (Elner et al., 2005; Nebel, Jackson, & Elner, 2005; Sutherland et al., 2000). In contrast, females, with their longer bills, may be better adapted to probe for submerged invertebrates including Polychaeta (Nebel et al., 2005; Sutherland et al., 2000).