Nesting biology and behavior of the Madagascar Harrier-Hawk (Polyboroides radiatus) in northeastern Madagascar

We studied the endemic Madagascar Harrier-Hawk (Polyboroides radiatus) duri ng the 1998 breeding season on Masoala Peninsula, northeaster Madagascar. O ne nesting pair was observed from courtship to 1 wk into the post-fledging period (September-January). Copulations started 25 d prior to egg laying an d peaked 7 d before egg laying. Two eggs were laid and the female and male incubated for 61.6% and 35.5% of 189.8 hr of nest observations, respectivel y. Incubation lasted 39 d from laying to hatching of the first egg. Both eg gs hatched but the second-hatched young died from siblicide at 7 d of age. The surviving young fledged at 50 d of age. Frogs (Boophis and Platypelis s pp.), geckos (Uroplatus and Homopholis spp.) and nestling birds were the mo st numerous prey taken, representing 82% of 160 identified prey items.