BEHAVIORAL ECOLOGY OF THE NORTH SULAWESI TARICTIC HORNBILL PENELOPIDES-EXARHATUS-EXARHATUS DURING THE BREEDING-SEASON

Two nests of the North Sulawesi Tarictic Hornbill Penelopides exarhatu s exarhatus were monitored for one breeding season (April-July). The f emales sealed themselves into the nest cavities and remained there for 70-90 days. Incubation was estimated at 16-19 days, and at both nests two offspring fledged. Tarictic Hornbills are cooperative breeders wi th up to three helpers at the nest and defend foraging territories of 72-139 ha. Food items delivered to the nest included fruits of 34 spec ies (85% of diet items) and invertebrates. Provisioning by helpers all owed breeding males to reduce investment in parental care and may acce lerate the development rates in chicks. Constraints on dispersal proba bly result from habitat saturation rather than living in an unpredicta ble environment.