A nesting pair of Gecinulus woodpeckers in a likely zone of intergradation between Pale-headed Woodpecker G. grantia and Bamboo Woodpecker G. viridis

Abstract

A nesting of a pair of Gecinulus woodpeckers in a possible zone of intergradation between the parapatric taxa Pale-headed Woodpecker G. grantia and Bamboo Woodpecker G. viridis is described. While the male looked like a more or less typical G. viridis the female bore plumage characters that appeared intermediate between G. grantia and G. viridis. Additionally a specimen labelled as G. grantia indochinensis, collected in Thailand in 1964 (the only record for that country), also appeared atypical, showing characters somewhat intermediate between G. grantia and G. viridis. It is likely that a narrow hybrid zone between G. grantia and G. viridis exists where the two come into contact in northern Thailand and, presumably, northern Laos. Recommendations for further surveys are made in order to determine the extent of postulated hybridisation, and additionally to investigate the ecological and taxonomic relations of these two taxa.