Sensitivities of Avian Feeding Guilds to Forest Edges and Habitat Structure in the Mahamavo Region, Madagascar

Abstract

Madagascar is experiencing widespread deforestation as a result of human activity which can significantly alter forest habitats and interfere with biological processes. Knowledge of these effects is critical for the country due to its high levels of endemism and lack of resources. The response of tropical bird species to forest edges and disturbance has been shown to vary based on feeding guild, but little research has been conducted on the topic in Madagascar. This study looked at the effect of forest edges and other habitat variables on feeding guild abundance and body mass in the Mahamavo forests of Madagascar. Birds were classified as frugivores-granivores if they ate mainly fruits and grains and were classified as insectivores if they ate mainly insects. I predicted that these two guilds would show high sensitivities to changes in forest configurations and that their abundances would show a positive relationship with edge distance. Bird point counts, forest surveys, and GIS were used to collect data on bird abundance and forest characteristics. Frugivores-granivores were the most sensitive guild to changes in habitat structure and showed an unexpected preference for forest edges. This response is likely related to food availability since this guild depends on plants that may require specific growing conditions and be more abundant at edges. Body mass showed at least some sensitivity for all guilds, indicating that the distribution of birds of different sizes within guilds is greatly affected by forest characteristics. Conservation decisions in this region should pay particular attention to frugivorous-granivorous species and focus on maintaining habitat diversity both within the forest and the surrounding agricultural matrix.