Meeting Abstract

S5-10   15:00 - 15:30  High-flying hummingbirds: Combining energetics with morphology and physiology to understand life at high elevation Groom, DJE; San Francisco State University dgroom@sfsu.edu https://dgroom.weebly.com/

Upward shifts in elevation have concomitant changes in a wide-range of environmental parameters, most notably reductions in oxygen partial pressure, temperature, and air density. Declines in these abiotic factors can have significant energetic repercussions for endothermic flying organisms. For example, drops in air density can hinder lift production, necessitating kinematic changes of the wings during flight, while lower ambient temperatures require greater energetic expenditure for thermoregulation. To overcome these abiotic challenges, high-flying birds possess a range of morphological and physiological traits that may compensate for or reduce daily energetic requirements. But biotic factors will also shift simultaneously with elevation, such as competition and food availability, and these biotic challenges will also confer some energetic cost. Therefore, to understand the biology of an elevational gradient, both biotic and abiotic factors must be considered together. Using hummingbirds, one of the best studied avian taxa that are found from sea level to the peaks of the Andes, I will review the specific morphological and physiological traits that may confer some energetic advantage, related to either increasing energy intake, reducing energy expenditure, or to successfully compete in their environment. I also consider the possible trade-offs of adapting to high elevations on individual performance. I will then connect it to our current understanding of other avian taxa, and whether patterns in hummingbirds are applicable to other clades.