Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Life Sciences
The Effect Of Food Availability On Time And Energy Expenditures Of Territorial And Non-Territorial Hummingbirds, Donald R. Powers, Todd Mckee
The Effect Of Food Availability On Time And Energy Expenditures Of Territorial And Non-Territorial Hummingbirds, Donald R. Powers, Todd Mckee
Faculty Publications - Department of Biological & Molecular Science
We studied the time and energy allocations related to territorial behavior in male Blue-throated Hummingbirds (Lampornis clemenciae; about 8.3 g) under conditions of unlimited and restricted food availability. When food was unlimited. territorial males avoided inter-specific aggression, chasing only 11% of the inter-specific intruders (Black-chinned Hummingbirds, Archilochus alexandri; about 3.5 g). Thus, when food was unlimited, inter-specific intruders were able to forage efficiently, meeting their estimated daily energy requirement with ease (27 kJ/day). Conversely, 81% of intraspecific intruders were chased, and intra-specific intruders were able to feed at territorial feeders only when the territorial male was away. Chases of …
Field Metabolic Rate And Food Consumption Of Two Sympatric Hummingbird Species In Southeastern Arizona, Donald R. Powers, Timothy M. Conley
Field Metabolic Rate And Food Consumption Of Two Sympatric Hummingbird Species In Southeastern Arizona, Donald R. Powers, Timothy M. Conley
Faculty Publications - Department of Biological & Molecular Science
We compared the field metabolic rate (FMR) and behavior around sugar-water feeders of sympatric territorial and non-territorial hummingbirds in the Chiricahua Mountains of southeastern Arizona during July 1987 and 1989. The territorial species was the Blue-throated Hummingbird (Lampornis clemenciae; mean mass 8.77 g) and the non-territorial species the Black-chinned Hummingbird( Archilochusa lexandri; mean mass 3.67 g). FMR (CO2p roduction)a nd watert urnoverw erem easuredu singt he doublyl abeledw ater technique. FMR averaged 81.7 kJ/day (n = 4) in L. clemenciae and 29.1 kJ/day (n = 4) in A. alexandri. Mean mass-specific FMR was higher in L. clemenciae (18.36 ml CO2 …
Effect Of Temperature And Humidity On Evaporative Water Loss In Anna's Hummingbird (Calypte Anna), Donald R. Powers
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 …