YANEGA, G.; RUBEGA, M.A.; Univ. of Connecticut, Storrs; Univ. of Connecticut, Storrs: A comparative study of the functional morphology of insectivory in hummingbirds

Hummingbirds (Trochilidae) are a speciose family of birds whose diets are composed of both arthropod prey and floral nectars. It has been hypothesized that the selective pressures driving variation in beak length and curvature are most closely related to nectarivory, although the consequences of variation in beak morphology for insectivory have yet to be addressed in a comparative context. We compared feeding performance, foraging behaviors, and morphology in seven hummingbird species (Thalurania colombica, Chalybura urochyrsia, Eugenes fulgens, Lampornis clemenciae, Archilochus colubris, Phaethornis longirostris, Threnetes ruckeri) from four clades. Species differed in the frequency with which they employed different modes of foraging (e.g. proportion of attempts to capture substrate-bound prey vs. airborne prey), and in their prey capture performance. In our previous work, we documented a novel form of mandibular flexion and spreading associated with aerial insectivory in hummingbirds. We document here that the use of this feature during aerial attack sequences is widespread in the family, and that the locus of intraramal mandibular flexion differs between the two major clades (�hermits�and �non-hermits�). In all cases jaw spreading appears to facilitate capture of aerial prey, despite some variation in the underlying morphology.