Breeding biology of the little blue Heron (Egretta caerulea) in southeastern Brazil.

The breeding biology of Little Blue Herons (Egretta caerulea) nesting in Santos-Cubatao, southeastern Brazil, was studied during the 1997 (75 monitored nests) and 1998 (65 nests) breeding seasons in one colony (Saboo River), and during the 1997 season (58 nests) in another colony nearby (Morrao River). Both mixed-species colonies were in mangroves affected by pollution and port activities. Colonies were active in September-March (Saboo River), and November-March (Morrao River). Little Blue Herons built their nests lower in the red mangrove (Rhizophora mangle) Morrao River colony where Scarlet Ibises (Eudocimus ruber) were the commonest nesting species, and nested higher in trees of the white mangrove (Laguncularia racemosa) Saboo River colony, where they were most common. Breeding chronology was similar to North American populations but clutch sizes were smaller (mean 2.21 to 2.57 eggs/nest), productivity lower (mean 0.53 to 0.98 young/breeding attempt) and young remained with adults for longer. Nest collapse, followed by predation, accounted for most failures. Parasitism by nematode worms may be an important source of mortality in some years. Differences in nest-sites between colonies resulted both from the vegetation structure and interactions with other nesting species; male herons likely tend to select the more exposed display territories (where nests will be built).

Fabio Olmos & Robson Silva e Silva, ORNITOLOGIA NEOTROPICAL 13: 17-30