Tropical Kingbirds (Tyrannus melancholicus) are common residents of Costa Rica. Their range is apparently expanding northward, as more and more accounts of them come each summer from as far as Southern Canada. Here is a Tropical Kingbird's "whit" call, performed at the Arenal Lodge. His "whit" note seemed to counterpoint a Black-striped Sparrow's, which was also calling in the "whit" style, 6/15/99.
This Western Kingbird was engaged in aerial combat with a Cooper's Hawk (Accipiter cooperii). Well, it was actually more a harrassment then combat. Kingbirds and other flycatchers harrass all hawks and Ravens on general principal - never give 'em an inch!