Foraging ecology of High Andean insectivorous birds in remnant Polylepis forest patches

I examined how High Andean insectivorous birds partition resources in remnant Polylepis forest patches at three locations in the Cordillera Vilcanota, southern Peru. A number of distinctive guilds were identified within the bird community based on the manner and location of foraging displayed by each species. Important dimensions that enabled differentiation amongst guild co-members were those that supported the partitioning of resources between guilds. The significant disproportionate use of substrates and prey-attack maneuvers by birds indicated substrate specialization within the insectivorous Polylepis bird community. These specializations provide a means by which Polylepis insectivores fit syntopically along a resource gradient. Insectivores demonstrated a differential response to foraging in smaller patches, and changes in the foraging regimes of four guilds between large and small patches were frequent. The most abundant insectivores in small patches were the least diverse foragers; they compensated behaviorally for changes in patch habitat quality by using fewer substrates and prey-attack maneuvers. Guild members that shifted their foraging regime to use fewer attack maneuvers were also more tolerant of small patches. Small Polylepis patches have a significant role in fragmented High-Andean ecosystem functioning by providing essential foraging habitat for insectivorous birds.