Guild-specific responses of birds to habitat fragmentation : evaluating the effects of different coffee production systems in Colombia
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Habitat loss and fragmentation are the main drivers of biodiversity loss, especially in the tropics, where the transformation of forested areas into agriculture is predicted to increase dramatically in the next five decades. Although several studies have elucidated the negative impacts of agriculture on biodiversity, recent work suggests that some agro-ecosystems, such as coffee plantations, are potential key environments for maintaining biodiversity and ecosystem services. This study evaluated the role of different coffee production types (sun-exposed, semi-shade and shade in polycultures or monocultures) on the bird communities associated with these agro-ecosystems in the tropical Andes of Colombia. It used a guild-specific approach and nonparametric statistical methods to identify the influence of particular environmental, ecological and landscape variables on the bird community assemblage and to assess potential changes in the species composition among management type. The potential responses of avifauna to fragmentation were studied from three different perspectives: i) from a patch-level point of view, evaluating the effect of local habitat factors (e.g. canopy cover, type of crop and crop management type); ii) from a species point of view, evaluating the role of species ecological traits (e.g. feeding habitat); and iii) from a landscape point of view, evaluating the effect of landscape configuration variables (e.g. patch area and perimeter length). The results indicated that polyculture and shade coffee crops host the most diverse avian communities and that guild representativeness varied among different coffee crop types. The type of coffee production type and the habitat characteristics associated with them seemed to have the greatest influences on families such as flycatchers, hummingbirds and wrens. Finally, coffee plantations can potentially contribute to the maintenance of bird diversity in anthropogenic landscapes; however these benefits are strongly influenced by the type of crop management. The maintenance of traditional coffee production (shade polyculture coffee) is recommended, and should be economically and socially encouraged.