AVIS-IBIS

Birds of Indian Subcontinent

Length of Feeding Day and Body Weight of Great Tits in a Single-And a Two-Predator Environment

Publication Type:Journal Article
Year of Publication:2000
Authors:Krams, I
Journal:Behavioral Ecology and Sociobiology
Volume:48
Issue:2
Date Published:2000
ISBN Number:03405443
Keywords:Accipiter, Accipiter nisus, Accipitridae, Glaucidium, Glaucidium passerinum, Paridae, Parus, Parus major, Strigidae
Abstract:The risk of predation may influence the acquisition of energy and the feeding activity of animals. Feeding activity and body reserves of wintering great tits Parus major in response to the priority to food access were studied in two areas differing in incidence of predators. The one-predator area contained sparrowhawks Accipiter nisus only, whereas the two-predator area contained both sparrowhawks and pygmy owls Glaucidium passerinum, whose hunting periods overlap at dawn and dusk. In the two-predator area dominant great tits arrived at feeders significantly later in the morning, and left earlier in the evening, than their subordinate flock-mates. Hence, feeding day length of dominants was found to be significantly shorter. The reverse was true for the one-predator area. In addition, dominants carried significantly greater reserves than subordinates in the area inhabited by two predators. Factors constraining subcutaneous energy reserves were also studied in removal experiments. After the removal of dominant individuals, subordinate great tits did not reduce their body reserves in the two predator area. In contrast, subordinate great tits significantly reduced evening body reserves in the single-predator area. I concluded that the presence of the two predators increases unpredictability in feeding conditions for great tits. Dominant individuals responded to this by shortening their feeding day and increasing body reserves at dusk.
URL:http://www.jstor.org/stable/4601791
Short Title:Behavioral Ecology and Sociobiology
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith