Department of Biology, University of Florida, Gainesville, FL 32611, UNITED STATES OF AMERICA.
The Holocene (the last ca. 10,000 yr BP) is usually thought of as a climatically stable period. Bird species distributions in the Neotropics are assumed to have been stable throughout this time as well. A review of recent literature, however, shows that climate was more variable. Although a picture about changes in plant distributions is now emerging, little is known about how animals might have responded to climatic change. Through a detailed study of comparative osteology, I analyzed the bird assemblages from five archaeological sites in coastal Ecuador (ca. 10,000–1670 yr BP) and one site from the northern Andes (ca. 2640–1700 yr BP) to establish how biogeographic patterns could be related to past climate or other natural as well as anthropogenic factors. This work suggests several broad patterns in bird exploitation and avian biogeography. Birds are only a minor component of archaeological sites in Ecuador, and prehistoric people in Ecuador consumed mostly common species from the immediate surroundings of their settlements. The dominant species are small to medium-sized birds (30–300 g) with terrestrial foraging habits that make them easy to hunt. Ease of procurement has probably influenced the decision by Early Holocene hunters of coastal Ecuador to focus on terrestrial and mangrove-associated animals, rather than marine birds and fish as in Peru. Biogeographically, this study shows that 20% of the species from archaeological sites no longer occur there in the present. Range changes can be attributed to human and natural changes in habitat. Deforestation may have been severe locally as at El Azúcar (2370– 2030 yr BP) where most species recovered archaeologically are open-habitat birds associated with brushy vegetation. Climate-induced changes are probably related to fluctuations in rainfall associated with the El Niño Southern Oscillation (ENSO). Tectonic uplift has significantly altered the distribution of mangroves and their associated avifaunas. Despite these changes most species have been able to rebound after severe habitat change and hunting in the past. I therefore suggest that in some areas habitat restoration projects could be more successful in the long term than implied by the current focus on areas of “pristine” habitat.