Birds of Indian Subcontinent

Sexual dimorphism and foraging niche partitioning in the Middle Spotted Woodpecker Dendrocopos medius

Publication Type:Journal Article
Year of Publication:2000
Authors:Pasinelli, G
Date Published:2000
ISBN Number:1474-919X
Keywords:Corvidae, Corvus, Corvus corone, Dendrocopos, Dendrocopos medius, Leiopicus, Leiopicus medius, Picidae, Picoides, Picoides medius
Abstract:I investigated sexual differences in morphology and foraging behaviour in the nearly monomorphic Middle Spotted Woodpecker Dendrocopos medius. In the northeastern Swiss lowlands, radiotracked birds were observed from 1994 to 1996 between January and June. The sexes overlapped in all morphological characters, with males (n= 25) being on average larger than females (n= 17). Bill-length and length of the crimson-red crown patch were most useful to discriminate the sexes. Sex-specific differences in foraging behaviour were found both within and between the prebreeding and breeding periods concerning the use of tree species, foraging techniques, relative height zones and living and dead substrates within a tree. Overall, both sexes had broader niches in the prebreeding than in the breeding period and niche overlap was larger during the latter period. Hence, sex-specific differences were more pronounced in the prebreeding than in the breeding period, indicating different niche use of males and females in the two periods. These varying patterns of sex-specific differences imply that niche segregation results from behavioural plasticity, probably based on dominance relationships between the sexes, rather than from sexual dimorphism.
Short Title:Ibis
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith