Behavior, diet, and breeding biology of Double-toothed Kites at a Guatemalan lowland site

We studied Double-toothed Kites (Harpagus bidentatus) in tropical lowland f orest at Tikal National Park, Peten, Guatemala, documenting behavior and di et during the incubation and nestling periods. These 200-g kites are Accipi ter-like in form and strikingly size-dimorphic for a kite. Modal clutch siz e was two, producing 0.63 fledglings per nesting attempt and 1.25 per succe ssful nest. Nesting was largely synchronous among pairs, with hatching duri ng the first month of the rainy season and fledging one month later Incubat ion lasted 42-45 days and nestlings fledged at 29.5 days on average. A radi o-tagged fledgling was fed near the nest for 35 days; 6-8 weeks after hedgi ng it dispersed at least 10 km, presumably reaching independence. Males did not incubate or brood, and rarely fed nestlings directly. Males typically provided most but not all prey (mainly lizards) during incubation and early nestling periods. Insects in the nestling diet increased through the nestl ing period as females increasingly hunted, often bringing in insects. These kites hunted from perches, below and within the closed canopy of tall, mat ure forest, taking 60.5% insects, 38.1% lizards, and 1.4% other vertebrates ; vertebrates comprised at least 75% of prey biomass. Most prey were taken from vegetation. but prey in flight also were captured. Active, adjacent ne sts averaged 1.35 km apart, for a maximum density estimate of 0.60 pairs km (-2) and a more likely estimate of 0.33-0.50 pairs km(-2) in homogeneous, f avorable habitat and 0.29-0.44 pairs km(-2) for Tikal National Park as a wh ole.