Conservation value of silvopastures to Neotropical migrants in Andean forest flocks

Abstract

In the face of continued loss of Andean forests, shade agroforestry is a promising approach where agricultural production and conservation can co-occur to support environmental and socioeconomic needs. Agroforestry systems provide habitat for a diverse avifauna, including several migratory species of concern. Unfortunately, shaded crops continue to be converted to sun monocultures and pastures which provide fewer ecosystem services, reduce habitat complexity, and support less biodiversity. Silvopastoral systems, which combine grazing pastures and trees, have recently been drawing worldwide attention. In an effort to evaluate the conservation value of little-studied silvopastures to Andean birds, we compared mixed-species flock communities associated with different forested habitats. In January–February of 2011–2013, species composition, flock size, and individual foraging heights were recorded for 446 flocks at 9 study areas in Antioquia, Colombia. We sampled shade-coffee, shade-cardamom, secondary forest, and silvopasture at ∼1,150–1,850m elevation and measured vegetative structure in each habitat. Less structurally-complex silvopastures supported smaller, less diverse flocks with fewer Neotropical migrants and resident forest specialists. Further, fewer male Blackburnian Warblers flocked in silvopastures compared to other habitats, which is consistent with other studies showing that overwintering male migrants tend to occupy the highest quality habitats. Although forest birds may be better served by silvopastures than conventional treeless pastures, our findings suggest that silvopastoral systems are less suitable for flocking birds than other forested habitats. However, agroforestry remains an important complementary approach to other strategies to maintain Andean forests and improve the conservation potential of degraded land.