1 - Why are tropical birds interesting?

Abstract

This chapter focuses on tropical birds that exhibit different ecology. In the tropical zones, a year is divided into the dry season and wet season unlike the spring, summer, winter, and fall seasons of the temperate zone. The timing and length of the dry and wet seasons vary with locale and latitude. Unlike birds of the temperate zone, tropical birds breed throughout the year. Frugivorous birds often breed during the dry season, while insectivorous birds breed during the longer wet season. Tropical/temperate zone differences in migratory behavior and breeding season set the stage for major differences in social behavior. The chapter describes and evaluates the evolutionary consequences of these latitudinal differences as they affect life history traits, mating systems, territoriality, and communication. The first simple and broad generalization is that species in temperate regions are under strong selection from abiotic factors, whereas in tropical regions, biotic selection pressures are the most important. Taxonomic diversity is the greatest difference between temperate zone and tropical birds. Strong biotic selection pressures mean that disruption of the environment and loss of species can quickly erase the evidence necessary to piece together evolutionary processes in the tropics. There is a temperate zone bias because the vast majority of biologists are based in temperate regions, many of whom are ignorant of the unique ecology and behavior of tropical birds. The chapter illustrates the examples of temperate zone bias: extra-pair mating systems, testosterone and territory defense, and territory acquisition.