Distribution and Behavioral Ecology of an Arboreal `Tarantula' Spider in Trinidad

The Theraphosid spider Avicularia avicularia is reported to be widely distributed in Trinidad. A population in 2.2 ha of an abandoned tonka bean plantation was studied for 18 months. Juvenile spiders lived between the leaves of low growing plants. Most older immatures and adult females constructed camouflaged silk retreats at a height of between 1.5 and 3 m on tree trunks. Most inhabited trees accommodated single individuals. Dispersion was aggregated with a bias towards larger trees. The population density of long-term residents and vagrants was estimated to be between 13 and 30 ha-'. Diel activity was closely correlated with changes in light intensity at dusk and dawn. Ecdysis, reproduction, and associated weight changes were strongly seasonal, adult males appearing in the latter part of the dry season and young being born in June and July.