Life Sciences Commons^™

Hummingbirds Budget Energy Flexibly In Response To Changing Resources, Anusha Shankar, Catherine H. Graham, Joseph R. Canepa, Susan M. Wethington, Don Powers

Faculty Publications - Department of Biological & Molecular Science

1. A key component of individual fitness is the ability to manage energy stores in response to variable resource availability, but because directly measuring energy budgets is difficult, daily energy management is rarely measured.
2. Hummingbirds' energy management is relatively simple to model compared to other endotherms because they have high mass‐specific metabolic rates and store little fat.
3. We determined which aspects of the hummingbird daily energy budget (i.e. thermoregulation, daytime activity costs, night‐time costs) change at the individual level in response to environmental variation.
4. We found that daily energy expenditure varied threefold in two populations of broad‐billed hummingbirds (Cynanthus latirostris …

Hovering In The Heat: Effects Of Environmental Temperature On Heat Regulation In Foraging Hummingbirds, Don R. Powers, Kathleen M. Langland, Susan M. Wethington, Sean D. Powers, Catherine H. Graham, Bret W. Tobalske

Faculty Publications - Department of Biological & Molecular Science

At high temperature (greater than 40°C) endotherms experience reduced passive heat dissipation (radiation, conduction and convection) and increased reliance on evaporative heat loss. High temperatures challenge flying birds due to heat produced by wing muscles. Hummingbirds depend on flight for foraging, yet inhabit hot regions. We used infrared thermography to explore how lower passive heat dissipation during flight impacts body-heat management in broad-billed (Cynanthus latirostris, 3.0 g), black-chinned (Archilochus alexandri, 3.0 g), Rivoli’s (Eugenes fulgens, 7.5 g) and blue-throated (Lampornis clemenciae, 8.0 g) hummingbirds in southeastern Arizona and calliope hummingbirds (Selasphorus calliope, 2.6 g) in Montana. Thermal gradients driving passive …

Effect Of Temperature And Humidity On Evaporative Water Loss In Anna's Hummingbird (Calypte Anna), Donald R. Powers

Faculty Publications - Department of Biological & Molecular Science

Evaporative water loss (EWL), oxygen concumption (V0 ), and body temperature (Tb) of Anna's 2 Hummingbirds (Calypte anna; ca. 4.5 g) were measured at combinations of ambient temperature (T J and water vapor density (Qva) ranging from 20 to 37 °C and 2 to 27 g · m-3 , respectively. The EWL decreased linearly with increasing eva at all temperatures. The slopes ofleast squares regression lines relating EWL to Qva at different temperatures were not significantly different and averaged -0.50mg H20·m-3 ·g-2 ·h-1 (range: -0.39 to -0.61). Increased Qva restricted EWL in C. anna more than has been reported for …