The cloud forests of the Tropical Andes of South America are home to a high diversity of endemic and restricted range bird species, but increasingly at risk from habitat loss. Forest loss often results in forest fragmentation, or division of remaining habitat into isolated patches of varying sizes and shapes. To better understand how cloud forest bird communities respond to fragmentation, we surveyed bird communities across a gradient of fragment patch sizes in the Western Andes of Colombia. Next, we asked which mechanisms might be driving extirpation of species from cloud forest fragments by relating avian functional traits to area sensitivity.