Panasci, Theresa – Comparative breeding ecology and success of roadside hawks in human-modified and forest habitats of Peten, Guatemala. 1995.
In 1993 and 1994, as part of the Peregrine Fund Inc. Maya Project, I compared the breeding ecology, density, and reproductive success of nesting roadside hawks (Buteo magnirostris) in two study plots. An 8.25-km2 plot in the primary forest supported 13 territorial pairs in 1993, but only five pairs attempted to nest. In 1994, this plot contained 11 territorial pairs, of which seven pairs nested. The 8-km2 slash-and-burn plot contained 12 territorial pairs in 1993, 10 of which nested. In 1994, this plot supported 13 territorial pairs, of which 10 nested. Both years, there were non-nesting territorial pairs, especially in the forest plot, that copulated, courted, and carried sticks but did not nest. Pairs in the slash-and-burn plot nested in smaller, more slender trees and at lower heights than did pairs in the forest plot. Forest nest-sites and random points differed significantly with respect to several habitat characteristics. Pairs in the pristine forest nested selectively in “bajo” forest habitat characterized by low topographic elevation, seasonal inundation, and a low canopy (10-15 m). In the slash-and-burn habitat, characteristics of nest-sites and random points did not differ significantly. One roadside hawk young fledged in the forest plot each year; the overall means for both study years were 0.17 successful nests per nesting attempt, and 0.08 fledglings per pair. In the slash-and-burn plot, five young fledged in 1993 and three young fledged in 1994; the overall means for the two-year study were 0.30 successful nests per nesting attempt, and 0.32 fledglings per pair. Sixteen roadside hawk nests failed during incubation, and eight failed during the nestling stage. Human persecution caused five slash-and-burn nests to fail. Rates of prey delivery to nests did not differ significantly between the two habitats, but prey type and size did. More amphibians (n = 25) were delivered to slash-and-burn nests than forest nests (n = 9), and more mammals were delivered to forest nests (n = 9) than to slash-and-burn nests (n = 2). Reptiles (57.1%) and amphibians (24.3%) were the main prey types delivered to nestlings in both habitats.