3 - Life history traits

Abstract

It has long been recognized that tropical birds differ fundamentally from temperate zone birds in their life history traits. This chapter discusses the life history traits of tropical birds. These birds have high nest predation, high adult survival, and small clutch sizes, which have a big impact on the evolution of other behaviors such as mate choice and territory acquisition. High nest predation rates in tropical birds are an artifact of habitat because a number of key studies were done in human-disturbed habitats or islands where predation rates were elevated. Many features of behavior and life history influence predation frequency, so a search for real latitudinal differences owing to habitat should take phylogeny into account. Most long-term intensive studies of populations report high adult survival based on resightings and recaptures of breeders. Tropical birds do have smaller clutches than temperate zone birds, the data are unequivocal. Brood manipulation studies are the standard tool to test whether food availability limits clutch size. The key predictions are feeding trips per young, offspring survival, and decrease in experimentally enlarged broods. Large clutch size may be costly not just in the immediate sense but also in terms of future costs to survival and fecundity. Birds in south temperate regions also have the same life history traits as that of tropical birds.