Meeting Abstract

82.5  Monday, Jan. 6 11:30  Ecological Implications of Hummingbird Feeding Mechanisms RICO-GUEVARA, A.*; RUBEGA, M.A.; UNIVERSITY OF CONNECTICUT; UNIVERSITY OF CONNECTICUT a.rico@uconn.edu

Our research addresses the overarching question: How do the mechanics of feeding define the limits and adaptive values of feeding behaviors? We study every step of hummingbird nectar capture and transport, in order to generate predictions that can be tested in the wild. We ask: 1) How do tongues collect nectar? 2) How is the nectar transported inside the bill to the throat? 3) How does biophysical modeling predict performance during nectar extraction from real flowers? 4) Do performance measurements in wild flowers support the proposed model? Our previous results demonstrated that capillarity equations are unsuitable to calculate energy intake rate (the building unit of foraging theories); therefore we need a new elucidation of hummingbird foraging ecology. Using our previous demonstrations of nectar trapping and intraoral nectar transport, we generated falsifiable predictions about the action of the tongue, and the volumes of nectar that can be collected and transported inside the bill, in the wild at real flowers. We used high-speed videography of hummingbirds at wild flowers, and direct measurement of floral nectar volumes, to test predictions about nectar extraction rates (fluid volume uptake [┬Ál/s]) for hummingbirds feeding at wild flowers. We obtained detailed measurements of nectar extracted per lick, and bill insertion distance in translucent, wild, flowers founding support for the discarding of the capillarity theory. We propose that the mechanical limitations of tongue-based nectar extraction define foraging behavior for hummingbirds and other nectarivores. Our downstream calculations of the rates at which birds can obtain nectar along several environmental axes inform how and where the limits of nectar uptake have shaped the distribution, ecology and evolution of hummingbirds and other nectar-feeding birds.