title: Energy intake rates and nectar concentration preferences by hummingbirds.
abstract: In a series of daul choice tests with large volume feeders, rufous hummingbirds preferred sucrose concentrations near those that maximized their instantaneous rates of energy intake. As predicted on theoretical grounds, energy intake rates increased with increasing sucrose concentration to a maximum then decreased above this maximum. Earlier experimental studies suggested that hummingbirds always prefer the highest available concentration. Our results are consistent with the data of these studies, but by using a wider range of concentrations than previous workers, we found that the hummingbirds discriminated against very concentrated solutions.
authors.affiliation: Department of Zoology, University of British Columbia, V6T 1W5, Vancouver, B.C., Canada.
authors.forename: Staffan
authors.initials: S
authors.lastname: Tamm
authors.affiliation: Department of Zoology, University of British Columbia, V6T 1W5, Vancouver, B.C., Canada.
authors.forename: Clifton Lee
authors.initials: CL
authors.lastname: Gass
keywords: Energy intake rates; Food selection; Humming birds; Nectar concentration; Selasphorus rufus