Gulliver travels to the fragmented tropics: geographic variation in mechanisms of avian extinction

peculiar, and if they were not so directly contrary to those of my own dear country, I should be tempted to say little in their justification” (Swift 1726). In Jonathan Swift’s classic tale, Gulliver’s Travels, Gulliver finds himself in unfamiliar and extraordinary lands. What makes his experiences so intriguing and comical are his transplanted notions of order and society colliding with the very different notions held by his exotic hosts. In a similar way, ecological inferences derived from one geographic area may not transfer smoothly to others and, in fact, may impede further understanding. Such may be the case when comparing the ecology and evolution of tropical and temperate avifaunas, particularly neotropical and northern temperate assemblages. Differences in life histories and behaviors between temperate and tropical birds have been recognized for a long time (Skutch 1949). Alexander Skutch, during a famous series of debates with David Lack about the latitudinal gradient in avian clutch sizes (Lack 1947; Skutch 1949), remarked that if most biologists had been raised in the tropics they would ask why temperate birds lay unusually large clutches, rather than asking, as did temperate biologists, why tropical clutches are so small. Similarly, Ricklefs (2002) noted that his time in the neotropics was pivotal in cementing the idea that many neotropical bird lineages are distinct from North American ones in both their evolutionary and life histories. The degree to which such differences influence the conservation of bird populations in human-dominated landscapes remains unappreciated. Nevertheless, two present-day commonalities exist between tropical and temperate birds. First, species in both realms are confronted with destruction and conversion of forests (Faaborg et al. 1995; Laurance et al. 2000). Areas of high endemism, such as the Atlantic rainforests of Brazil, the northern and central Andes, and Amazonia, are particularly at risk (Balmford and Long 1994). Secondly, many species respond negatively to such disturbances and their populations decline or disappear in fragmented landscapes. Local extinction of species from fragmented forests is well documented across northern temperate areas (Whitcomb et al. 1981) as well as in the neotropics (Stouffer and Bierregaard 1995; Robinson 1999, 2001). Thus, temperate and tropical birds face similar challenges. Yet the mechanisms producing the observed declines in species richness may differ between 85