BEHAVIOR ECOLOGY OF TROPICAL BIRDS

The main theme of this book is to illustrate, how, and why tropical birds are so different from temperate zone birds. The book's purpose is to dispel the temperate zone biologist's ignorance of tropical biology and to stimulate more research on tropical birds. There is a temperate zone bias that derives from the great number of researchers based in temperate regions of North America and Europe. Because of this sampling bias, most theory in avian behavioral ecology comes from models and empirical studies of temperate regions, but these theories do not apply equally well to tropical birds. Tropical birds greatly outnumber temperate zone species, yet are so poorly studied that even fairly basic behavioral ecology experiments have rarely been done. Temperate zone birds are atypical because they are constrained by climate to breed in a short time span, and many behavioral adaptations like extra-pair behavior, high testosterone, divergent sex roles in territory defense and parental care all stem from their short breeding seasons and seasonal breeding territoriality. Tropical birds are not so constrained by climate, and most tropical passerines defend territories year round, not just for the breeding season. For instance, extra-pair fertilizations are now considered the norm for temperate passerines and strict monogamy is exceptional. But tropical passerines do not experience intense sperm competition and extra-pair fertilizations are uncommon. Similarly, work on testosterone in temperate zone birds has shown that high levels of testosterone are important for successful territory defense, gaining extra-pair fertilizations and high song output in males. Males of tropical species havevery low testosterone despite strong territorial behavior and singing.