Changing land use: Problems and opportunities

Under the pressure of increasing human populations and expanding demands for food and fiber, native tropical and temperate habitats are becoming more restricted, and populations of many resident and migratory birds are declining. Mist net surveys of 111 forest and agricultural sites in Mexico, Belize, and Guatemala show that some migratory species use a wide variety of habitats during the non-breeding season; other migrants, especially ground-feeding insectivores that nest in temperate forests, are largely restricted to forest habitats during the northern winter. Most tropical residents are also scarce or absent in agricultural habitats; this is especially true of the suboscine families, which are an important component of tropical forests: Furnariidae, Dendrocolaptidae, Formicariidae, Tyrannidae, and Pipridae: Of the various agricultural habitats studied, arboreal crops, especially mature citrus and cacao, were used by a wide variety and relatively large number of migrants; at the other extreme, few birds were captured or observed in commercially grown allspice and platanos (bananas). Although habitat constraints on many species are increasing, the impact of these constraints can be reduced through research, management, legislation, and especially education. Long-range habitat management objectives that reduce forest fragmentation and promote retention of critical habitats for species can be realized if an informed and concerned public can be created