Grouping and cooperative breeding in the Great Slaty Woodpecker

LAMMERTINK, M.

THE CONDOR

COOPER ORNITHOLOGICAL SOC

Año: 2004 vol. 106 p. 309 - 319

0010-5422

Grouping and associated behavior are poorly documented for the Great Slaty Woodpecker (Mulleripicus pulverulentus) of Southeast Asia. This woodpecker is thought to breed in pairs, although only three active nests have been superficially described. I present observations of group and breeding behavior of the Great Slaty Woodpecker from five regions in western Indonesia. Thirty-six independent units of Great Slaty Woodpeckers involved predominantly groups (81%), followed by pairs (17%), and one single bird. Mean size of groups larger than 2 was 4.2 +/- 1.2 (range 3-6) individuals. Group size did not vary as a function of time of year, logging disturbance, or the number of sympatric woodpecker species. Individuals attended the same groups on consecutive days. Groups comprised several males and females. Roost holes, spaced >200 m apart, were occupied by single birds. In 65% of foraging groups, two to five members simultaneously exploited a single food source such as a stingless bee, termite, or ant nest; frequency of food-source sharing peaked at groups of four individuals. Within foraging groups, females spent more time climbing and searching; males did more hammering, pecking, and flaking. Grouping in this species is perhaps induced by cooperatively searching for and exploiting infrequent but highly profitable food sources. Two nests of Great Slaty Woodpeckers were found, one of which was attended by two males and one female. In 18% of occasions, Great Slaty Woodpecker groups associated temporarily with White-bellied Woodpeckers (Dryocopus javensis). In mixed flocks the two species exploited different food sources within 50 m from each other.