Knowledge of species habitat requirements, movements, and life cycles is important for understanding their ecology and functions in ecosystems, and is critical for enabling their effective conservation and monitoring, particularly in small-island states where conservation resources are limited. Island biogeography and ecological release theories make broadly supported predictions about the evolution of generalist traits among small-island birds in the Caribbean, and this research examines the influence of small-island conditions on the life cycle adaptations, diets, and distribution of birds and their responses to human land-use such as agriculture to inform conservation research and management. Using mist-netting, I found that 10 common terrestrial bird species on Grenada (3 endemic to the East Caribbean) exhibited similar patterns of low breeding period seasonality, followed by synchronized peaks in moult intensity and uncommonly high rates of moult-breeding overlap during peak rainfall and high arthropod abundance, despite the wide range in size, morphology, and phylogeny of these species. I studied patterns of seasonal diet composition and diet-overlap among species using DNA meta-barcoding of feces, which suggested that moult-breeding overlap may result from restricted time periods over which arthropod availability is sufficient for breeding and moult to occur. Diet analyses also indicated that agricultural habitats provide important year-round food sources. Lastly, repeated point-count surveys indicated increased bird diversity and abundance at high elevations and in closed-canopy habitats during the dry season, while many birds moved to low elevations and open-canopy habitats in the wet season. Much of Grenada consists of a diverse mosaic of closed-canopy secondary forest patches, interspersed among more open agroforests and small-scale cropping and grazed areas. These agroecosystems appear to provide important habitats and foods to birds throughout the year, especially more-open canopy agroforests in the wet season, while intact canopy forests provide important dry season habitat, which may be particularly important for species in lowland coastal fringe areas experiencing more intensive agricultural, urban, and resort development. This research demonstrates life history adaptations of birds on small islands, the importance of maintaining habitat diversity at local and landscape scales for species conservation, and the contribution of diverse small-scale agroecosystems to supporting small-island bird communities.