A Quantitative Study of Foraging of Male and Female Spruce‐Woods Warblers

Abstract

Males of four congeneric species of wood warblers (Parulidae) inhabiting a spruce forest of coastal Maine were found to forage higher than their females. They were the Magnolia (Dendroica Magnolia), Myrtle (D. coronata), Black—throat Green (D. virens), and Blackburnian (D. fusca) warblers. The foraging areas of males were nearer the height of their singing areas than were their nests, while foraging areas of females were nearer the height of their nest than the singing perches of their males. Very few differences were observed between sexes in the part of the tree utilized (proximal parts of limbs, tips of foliage, etc.) During the period of incubation, the foraging rates of females became noticeably greater than those of their males; before and after this period differences were less pronounced or non—existent. The partitioning of sexes results in a situation where males can forage readily while remaining maximally conspicuous, and females can forage in an area maximally adjacent to their nests. During this period males spent much of their time in territorial activities, females in nesting activities.