Plumage, Size, and Sexual Dimorphism in the Queen Charlotte Islands Hairy Woodpecker

Abstract

Plumage, size, and sexual dimorphism of the endemic Hairy Woodpecker subspecies Picoides villosus picoideus are described and compared with a less isolated insular population. Museum specimens of P. v. picoideus from the Queen Charlotte Islands, British Columbia were compared with P. v. harrisi specimens from Vancouver Island, British Columbia. Specimens from the two localities are similar in size, although the culmen of P. v. picoideus is 5-6% shorter. In plumage, P. v. picoideus is distinct in having markings on the belly and flanks, dorsal barring, and barring on the outer rectrices. The breast and belly are much darker and the wing coverts have fewer white markings in P. v. picoideus than in P. v. harrisi. Adults and juveniles, and adult males and females, differ only in minor features of plumage. Adult plumage of P. v. picoideus and insular populations of P. villosus in Newfoundland and the Grand Bahamas resembles juvenal plumage in mainland locations, and includes ancestral traits in this woodpecker lineage. Sexual dimorphism in size is similar in P. v. picoideus. P. v. harrisi, and continental populations, suggesting no ecological release of the sexes on the Queen Charlotte Islands or Vancouver Island. Relative sexual dimorphism in bill size varies little over the species' range, hence appears to be influenced little by ecological factors.