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Ecology of the West Indian Red-Bellied Woodpecker on Grand Cayman: Distribution and Foraging
Alexander Cruz and David W. Johnston
The Wilson Bulletin
Vol. 96, No. 3 (Sep., 1984), pp. 366-379
Published by: Wilson Ornithological Society
Stable URL: http://www.jstor.org/stable/4161953
Page Count: 14
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The West Indian Red-bellied Woodpecker (Melanerpes superciliaris) is resident throughout Grand Cayman in suitable habitats from mangrove to dense limestone forests. Despite the overlapping ranges found for weight, culmen, and tarsometatarsal length, mean values were significantly higher in males than in females. When the differences found in those characters that are important for feeding (e.g., bill size) in M. superciliaris are compared with the intersexual differences in foraging behavior, a relationship between dimorphism and feeding niches seems evident. The predominant foraging methods are fruit-eating (37.7%), gleaning (23.9%), probing (20.6%), and pecking (13.4%). Compared with the female, the male was often seen pecking. The larger-billed males are probably better adapted for pecking and feeding in the deeper levels of the bark and cambial layer. The intersexual differences in gleaning were statistically significant, the females gleaning more frequently. We expected to find the smaller female foraging upon smaller substrata (i.e., outer branches and higher up in trees). With the exception of the lower trunk, there were no statistical differences in the use of zones, although the females also tended to use the upper trunk and inner branches with a greater frequency than the males. There were significant differences in the foraging heights, with the males foraging higher. In their daily activities, pairs of M. superciliaris were often seen in close proximity, maintaining contact vocally. Sexual partitioning of the foraging resources is a possible mechanism of facilitating social organization in M. superciliaris by reducing intersexual aggression and competition.
The Wilson Bulletin © 1984 Wilson Ornithological Society