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The Colonization of Barbados by Cattle Egrets (Bubulcus ibis) 1956-1990

Elizabeth A. Krebs, Deborah Riven-Ramsey and W. Hunte
Colonial Waterbirds
Vol. 17, No. 1 (1994), pp. 86-90
Published by: Waterbird Society
DOI: 10.2307/1521386
Stable URL: http://www.jstor.org/stable/1521386
Page Count: 5
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The Colonization of Barbados by Cattle Egrets (Bubulcus ibis) 1956-1990
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Abstract

We describe the colonization of Barbados by the Cattle Egret (Bubulcus ibis) from initial settlement until 1990. The first egrets were observed in Barbados in 1956 as migrants that roosted at a location on the southern coast of the island. A permanent breeding colony was established at this location in 1972. Two additional breeding colonies were formed in the island in 1978 and 1980, and one permanent roosting colony in 1984. Suitable colony sites are unlikely to be yet limiting in Barbados, as colonies are established in very different vegetation types. Only two of the colonies are situated over water, suggesting that proximity to water is not a requirement for colony location in Barbados. Space limitation at the colony site does not appear to influence the formation of new colonies because: (1) the location of colonies at sites moved, expanded and contracted seasonally, (2) only 10-30% of all available space at a site was used in the four colonies, and (3) only between 33-60% of the space actually known to have been used at a site was in use at any given time. The colonies were evenly spaced around the island, suggesting the possibility that the distribution of new colonies is influenced by the advantage of minimizing foraging overlap between colonies. Population size on the island (in at least two of the four colonies) is still increasing. The size of the oldest and largest colony has changed little over the past three years. Weekly counts indicated that the number of birds in the roosting colony was negatively correlated with that in the breeding colonies, suggesting some short-term movement of birds between colonies.

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