Tropical Dry-Forest Mammals of Palo Verde
ECOLOGY AND CONSERVATION IN A CHANGING LANDSCAPE
Kathryn E. Stoner and Robert M. Timm
Mesoamerica contains some of the world's most diverse forests. It has at least 20 major life zones, based on variations of temperature and precipitation that can be broadly summarized in five tropical forest types—dry forest, wet forest, montane forest, coniferous forest, and mangrove swamp (Holdridge et al. 1971). When the Spaniards arrived in the New World, there were perhaps 550,000 km2 of dry forest on the Pacific side of lowland tropical Mesoamerica. This dry forest occupied as much or more of the Mesoamerican lowlands as did wet forests. Unfortunately, no habitat type in Mesoamerica has been more influenced by humans than the tropical dry forest; today less than 1 percent remains intact, with less than 0.01 percent under protection.
In Costa Rica tropical dry forests occur throughout the Pacific lowlands of Guanacaste Province and adjacent Puntarenas Province from sea level to about 500 m. Costa Rica's dry forest is characterized by a five- to six-month dry season from December through May, an annual precipitation of approximately 1,500 mm, and an average annual temperature higher than 24°C (Maldonado et al. 1995). These dry forests are largely deciduous today and encompass heterogeneous habitats varying in species composition, abundance, rainfall, and soils. These characteristics contribute to creating a harsh and heterogeneous, yet seasonally resource-rich, environment for the native mammals.
Mesoamerica has a diverse mammal fauna that includes elements from both North and South America as well as endemic species. More than 275 species in 28 families are recognized from the region, at least 17.8 percent of which are endemic to Mesoamerica. The mammals of the tropical dry forest are among the most poorly known of any of the bioclimatic life zones. Mammals that inhabit tropical dry-forest areas must be capable of dealing with high temperatures (to 40–41°C), very low precipitation in the dry season, and large fluctuations in the availability