Tropical forests in the Americas are undergoing rapid conversion to commercial agriculture, and many migratory bird species that use these forests have experienced corresponding populations declines. Conservation research for migratory birds in the tropics has focused overwhelmingly on shade coffee plantations and adjacent forest, but both cover types are now in decline, creating an urgent need to evaluate conservation opportunities in other agricultural systems. Here we compare how a community of 42 Neotropical migratory bird species and a subset of five conservation-priority species (Golden-winged Warbler, Blue-winged Warbler, Kentucky Warbler, Worm-eating Warbler, and Wood Thrush) differ in usage and habitat associations among a secondary forest baseline and four expanding commercial plantation systems in Guatemala: African oil palm, teak, rubber, and mixed-native hardwoods. We conducted avian point-count surveys during two consecutive overwintering seasons and analyzed avian abundance, species richness, and Shannon’s diversity index in response to cover type and vegetation metrics.
Results/Conclusions
We found that mixed-native hardwood plantations supported the highest richness and diversity of all migrants and that the three hardwood plantation types generally outperformed oil palm in richness and diversity metrics. Despite this, oil palm supported high abundance of several common species undergoing population declines and may therefore play an important role in conserving the common, widespread species that use that plantation type. Secondary forests hosted low abundance and diversity of the full migratory community, but high abundance and richness of conservation priority migrants along with native hardwood and teak plantations. Furthermore, the retention of tall overstory trees increased all migratory bird metrics in all plantation types. Our results indicate that conservation opportunities exist in all four agroforestry plantation types, though the species likely to benefit from conservation action will vary among plantation types. For the subset of conservation priority migrants, our results suggest that conservation efforts should combine strategies that retain and restore secondary forest, promote the adoption of native hardwood and teak plantations, and promote the retention of tall, remnant trees in agricultural landscapes.