TEMPORAL AND SPATIAL PATTERNS OF NESTING WITHIN A BREEDING COLONY IN SOUTHEASTERN BRAZIL

Resumo

Breeding colony of Anhinga (Anhinga anhinga), Great White Herons (Ardea alba), Snowy Egrets (Egretta thula), Cattle egret (Bulbucus ibis) and Black-crowned Night Herons (Nycticorax nycticorax) was monitored for, during 1988 till 1989, for: 1) number of breeding pairs, 2) beginning of the breeding period, and 3) height of nest. Similarities and dissimilarities in these three parameters were analyzed to explain temporal and spatial patterns of nesting within the colony. A temporal segregation occurred between the two greatest populations of Black-crowned Night Herons and Cattle Egret. The reproductive temporal sequence observed was Black-crowned Night Herons, Great White Herons and Snowy Egrets, Anhinga and Cattle Egret. Such sequence may be due to the fact that more piscivorous species breed during low water period. The analysis of nests locations showed a vertical stratification of the populations. These results support the notion that species that overlap temporally, segregate vertically in their nest location. Reproductive success of the studied populations were similar to results found in temperate regions. It is suggested that the temporal and vertical structure of the breeding colony is associated with the local structure of the vegetation.