Feeding ecology of a population of nesting yellow warblers

Abstract

The feeding ecology of a population of nesting yellow warblers (Dendroica petechia) was studied on the Delta Beach Ridge, Manitoba, during the breeding seasons of 1975 and 1976. The total numbers and taxonomic composition of the arthropods available to yellow warblers fluctuated irregularly throughout both breeding seasons. Major changes in the arthropod fauna were due mainly to emergences of adult chironomids. Chironomidae was the most abundant group during both breeding seasons and comprised more than half of the available prey. Arthropods were more numerous in the lower vegetation (0.3–3.0 m) than in the upper vegetation (7.0–9.0 m).Adult chironomids were the chief prey, comprising 58 and 56% of the diet in 1975 and 1976, respectively. The diets of males and females were similar throughout the breeding seasons. The prey consumed by yellow warblers varied temporally and spatially according to the arthropods available; prey was taken in proportion to its availability.Foraging males and females partitioned the habitat with respect to tree species, foraging height, tree section, height of tree selected, foraging methods, and length of movements between foraging bouts.