Flock characteristics of ant-following birds in premontane moist forest and coffee agroecosystems

We studied avian attendance at swarms of Eciton burchelli and Labidus praed ator (Hymenoptera: Formicidae: Ecitoninae) over 5-mo periods in both 1996 a nd 1997, at elevations between 1400 m and 1800 m in western Panama. We cond ucted area searches for swarms of raiding ants and attendant birds in intac t forest, traditional shade coffee habitats both adjacent to and distant fr om forest, and in sun coffee habitats, quantifying the size and composition of attendant flocks. All habitats except sun coffee supported numerous arm y ant swarms and thus a diverse assemblage of ant-following birds. A total of 411 swarming occasions attracted 126 bird species of 28 families. Of the 103 resident species, two were obligate ant-following birds, the Ruddy Woo dcreeper (Dendrocincla homochroa) and the Gray-headed Tanager (Eucometris p enicillata). Of the remaining species, 18 were wintering Nearctic migrants, and five were transient Nearctic migrants. Nearctic migrant species compos ed a greater percentage of the attendant species in shade coffee habitats a s compared to forest. Several species of forest resident birds that corresp ond with particular foraging guilds, such as understory bark insectivores, including D. homochroa, regularly occurred in adjacent shade coffee but wer e never observed at swarms in distant shade coffee. Army ants may therefore be a mechanism for bringing forest birds into shade coffee, but only to a point. In western Panama, mid-elevational traditional shade coffee plantati ons can provide additional habitat for the diverse avifauna that attend arm y ant swarms. With increasing distance from large areas of continuous fores t, however, the value of traditional shade coffee habitats is lessened for certain components of the bird community. Thus, protection of these habitat s adjacent to intact forest should receive priority. Additionally, current transformation of coffee-growing practices, including the removal of shade trees to grow coffee in full sun, will negatively affect army ants and thei r associated avian followers.