The effects of temperature and light intensity on the foraging behavior of the Ruby-throated Hummingbird (Archilochus colubris).

Abstract

Foraging behavior was observed in the Ruby-throated Hummingbird, Archilochus colubris, to determine if temperature and/or light intensity affected choice of foraging sites. The experiment was conducted at the University of Michigan Biological Station during the spring of 1992. Four different feeders were set up, two in a shaded area and two in an unshaded area. We recorded temperature, light intensity, number of visits to each of the feeders and feeding time per visit. We found no significant difference between the number of visits and mean feeding time in the shade and sun (p=0.590 and p=0.807, respectively). Temperature and mean feeding time were found to be significantly related (r2=0.131, N=62, p=0.004), with feeding time decreasing as temperature increases. We concluded that the hummingbirds do not choose feeding sites based on temperature or light intensity, and that they spend less time feeding as temperature increases.