ECOLOGY AND BREEDING HABITS OF THE SAVANNA HAWKIN THE LLANOS OF VENEZUELA

The ecology of the Savanna Hawk (Buteogallus meridionalis) was studied in the palm-savannas of Venezuela in 1978-1980. Pairs produced only one egg per clutch, no more than one young per calendar year, and had eggs or young in nests from February to December, coinciding largely with the wet season. In comparison to North American Red-tailed Hawks (Buteo jumaicensis), Savanna Hawks had significantly fewer young per pair per year, lower nest success( 47.1% vs. 82.5%), mainly due to lower hatching success( 64.1% vs. 84.4%) and a lower proportion of pairs laying eggs (73.3% vs. 88.0%). Survival of young Savanna Hawks from hatching to near fledging was 70.4%, and the adult survival rate, 7 1.1%; these values are approximately equal to those for Red-tailed Hawks. The brood size was artificially doubled from one to two at 10 Savanna Hawk nests, but the adults could find only enough food to feed and raise one chick in most cases. Food appeared to be both the ultimate and proximate factor controlling the timing of breeding.

WILLIAM J. MADER, Condor 84261-271