BREEDING BIOLOGY AND BEHAVIOR OF THE PLUMBEOUS KITE

We studied Plumbeous Kites (Ictinia plumbea) in Tikal National Park, P eten, Guatemala, from 1991-1996. We documented productivity of 19 nest ing attempts and studied behavior at six nests each during incubation and nestling periods. Nesting was highly synchronous among pairs, with eggs hatching late in the dry season and young hedging at the onset o f the rainy season, a time of maximal prey abundance. Kites built stic k nests high in exposed situations in living or dead trees, often reus ing the same nest or a nearby alternate site in subsequent years. We o bserved only clutch sizes of one. Based on museum records, latitudinal variation in clutch size occurs, with single-egg clutches the norm ex cept at the northern-and southernmost limits of the species' range, wh ere two-egg clutches have been found. Fifty-eight percent of eggs hatc hed, and 64% of those resulted in hedged young, producing 0.37 fledgli ngs per nesting attempt. Pair members shared incubation duties in a 60 :40 ratio, and each adult caught its own food throughout the nesting c ycle, differing from most raptors in these respects. We hypothesize th at these patterns result from prey characteristics that make it ineffi cient for the male to provision the female at the nest. During incubat ion, one adult or the other was on the nest 97.8% of the time, and inc ubation shifts averaged 1.99 h. Two incubation periods were 32 and 33 days, and four nestlings fledged at an average age of 38.5 days. Simil ar to Mississippi Kites (Ictinia mississippiensis) in most regards, Pl umbeous Kites laid a smaller clutch, and, unlike Mississippi Kites, he ld regularly-spaced breeding sites 0.5 km apart and exhibited intraspe cific territorial behavior.