BEHAVIOR, DIET, AND BREEDING BIOLOGY OF DOUBLETOOTHED KITE AT A GUATEMALAN LOWLAND SITE

We studied Double-toothed Kites (Harpagus bidentatus) in tropical lowlandforest at Tikal National Park, Peten, Guatemala, documenting behavior and diet during theincubation and nestling periods. These 200-g kites are Accipiter-like in form and strikinglysize-dimorphic for a kite. Modal clutch size was two, producing 0.63 fledglings per nestingattempt and 1.25 per successful nest. Nesting was largely synchronous among pairs, withhatching during the first month of the rainy season and fledging one month later. Incubationlasted 42-45 days and nestlings fledged at 29.5 days on average. A radio-tagged fledglingwas fed near the nest for 35 days; 6-8 weeks after fledging it dispersed at least 10 km,presumably reaching independence. Males did not incubate or brood, and rarely fed nestlingsdirectly. Males typically provided most but not all prey (mainly lizards) during incubationand early nestling periods. Insects in the nestling diet increased through the nestling periodas females increasingly hunted, often bringing in insects. These kites hunted from perches,below and within the closed canopy of tall, mature 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, adjacentnests averaged 1.35 km apart, for a maximum density estimate of 0.60 pairs km-2 and amore likely estimate of 0.33-0.50 pairs km-2 in homogeneous, favorable habitat and 0.29-0.44pairs km-2 for Tikal National Park as a whole.Key words: behavior, breeding biology, diet, Double-toothed Kite, Harpagus bidentatus,Neotropical forest, raptor.

MARK D. SCHULZE, JOSE Luis C~RDOVA, NATHANIEL E. SEAVY AND DAVID E WHITACRE, The Condor 102:113-126