Almarie Joyce L. Divinagracia (February 2008)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
The Visayan Writhed Hornbill Aceros waldeni, is the largest hornbill in the Visayas measuring for up to 79cm. It is at present critically endangered in its habitat in the forest of Panay and Negros islands. There is a prediction that nest defense among parent birds increases as nestling age increases (Trivers 1972, Barash 1975). Andersson (1980), Harvey and Greenwood (1978) hypothesized that nest defense intensity should increase with nestling age due to decreasing differences between expected future survival of parents and offspring and due to increases conspicuousness to predators of nestlings during the nestling period. The bird keeper and the stranger was exposed to the hornbills at 10, 5 and 0.5 meters from the enclosure while the researchers, who was situated in an observation post not visible to the birds, recorded the number of no active movements, hops and jumps from perch to perch for 3 minutes each distance. The results displayed that the sex of the Visayan Writhed Hornbill is dependent on the behavior it displays when exposed to either the bird keeper or the stranger. The type of behavior it displays is dependent on the distance of the keeper from the enclosure.