Avian ecologists have long been interested in understanding the mechanisms that drive differences in life history traits, such as clutch size, between temperate and tropical birds.

Until now, however, advancing our understanding of these mechanisms has proceeded slowly, largely because we lack information on the demography and breeding ecology of tropical species.

Moreover, comparisons between tropical to temperate trends in life history traits typically fail to control for phylogenetic influences. In other words, we don't know whether similarities among birds living in either habitat are due to the birds being related or due to their sharing similar habitats. Louis J. Sheehan, Esquire