Seasonal changes in woodpecker foraging patterns

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Foraging methods and habitats used by the predominant members of an excavating guild, Downy (Picoides pubescens), Hairy (P. villosus), and Pileated (Dryocopus pileatus) woodpeckers, were studied in southwestern Virginia during the breeding, postbreeding, and winter seasons. Seasonal variation of foraging methods and sites used by the three woodpeckers may be related, in part, to the birds' ability to excavate into trees. Downy, Hairy, and Pileated woodpeckers differed in their changes in the breadths of their foraging methods and the microhabitats they used. Downy Woodpeckers did not make the entensive excavations necessary to reach concentrated food sources, such as carpenter ants, during winter but increased the breadth of their resource use in all aspects of foraging behavior examined. Pileated Woodpeckers are strong excavators and decreased breadth primarily by excavating into tree trunks during the winter to exploit concentrated food sources. Hairy Woodpeckers, with excavating capabilities intermediate between Downy and Pileated woodpeckers, demonstrated an intermediate change in the breadth of their foraging behavior. Selection of different foraging microhabitats may account for more of a reduction in overlap among the three woodpecker species than other aspects of foraging behavior examined. Also, seasonal changes in overlap among species suggest an inverse relationship between overlap of species macrohabitats (stand structure) and microhabitats (sizes of trees and positions in trees used for foraging). As woodpeckers forage in more similar stands, they may use less similar trees and positions in trees as foraging sites.

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Reference Code: A81CON02IDUS

Full Citation: Conner, R. N. 1981. Seasonal changes in woodpecker foraging patterns. Auk 98(3): 562-570.

Location: ANIMAL EF: BIRDS