BREEDING BIOLOGY OF THE CRESTED CARACARA IN THE CAPE REGION OF BAJA-CALIFORNIA, MEXICO

The breeding biology of the Crested Caracara (Caracara plancus) was st udied during the 1990 and 1991 breeding seasons in Baja California Sur , Mexico. Sixteen nests were monitored in 1990 and six in 1991. The br eeding season extended from February-August. Caracaras were more abund ant during the post-fledging period (October-November) when up to 1.2 birds/km were registered in road surveys. The cardon cactus (Pachycere us pringlei) was the most used structure for nesting (76% of nests), a lthough other tree-like structures were also used. Nest material consi sted mainly of twigs of rama parda (Ruellia peninsularis), coralvine ( Antigonon leptopus) and condalia (Condalia globosa). Nesting success e stimated using the Mayfield method was 0.75 and 0.38 in 1990 and 1991, respectively Mean (+/-SD) productivity was 2.2 +/- 0.4 and 1.8 +/- 0. 7 fledglings per successful nest in 1990 and 1991, respectively. Five second clutches were registered. The productivity of the Cape region C rested Caracara population was similar to that reported for caracaras in Texas but higher than in Arizona.