Ecology, and Conservation Status of
Costa Rican Dry-Forest Avifauna
Gilbert Barrantes and Julio E. Sánchez
IN COSTA RICA the dry forest covers the Santa Elena Peninsula and adjacent areas and some small areas around the Gulf of Nicoya (Slud 1980; Gómez 1986; see maps in chapter 1). Large tracts of semideciduous forest also occur below 500 m in the northwest of Costa Rica. For the purpose of this chapter, we consider deciduous, semideciduous, and other associated habitats as the dry-forest ecosystem. The ecosystem includes both terrestrial and aquatic habitats. Deciduous and riparian forests and savanna are the most extensive terrestrial habitats, and mangroves, mudflats, lagoons, and swamps are the most common aquatic habitats. Mangroves and mudflats cover large areas in the Gulf of Nicoya, and lagoons and swamps are part of the complex hydrological system that occurs at the lower basin of the Tempisque River. We excluded more humid areas of the Nicoya Peninsula (e.g., Reserva Absoluta Cabo Blanco; Gómez 1986).
The average temperature of the region is 27.6°C ± 0.7°C and the annual precipitation 1,619 mm (Gómez 1986). Temperature varies little throughout year. Precipitation, however, fluctuates dramatically, with a well-defined dry season from December to May (some years to June) (see chapter 1). Seasonality in the dry-forest ecosystem largely influences species composition, food resource availability, habitat use, and, to a large extent, mutualistic interactions that occur in this life zone.
Most of this chapter's information on avian species richness, migratory status, habitat use, and reproduction comes from years of fieldwork by the authors. We complemented our data on some aspects of the reproduction of some species with information from Slud (1964) and Stiles and Skutch (1989). We also used part of the