Inter-annual diversity of birds in the shoreline of an island in the southern Gulf of Mexico

Isla del Carmen lies within a natural protected area in the southern Gulf of Mexico and supports many plants and animal species of ecological conservation concern. However, rapid urbanization threatens its biodiversity. Although many animal groups here are relatively well studied, there is a lack of monitoring of the bird communities at least during the last 15 years. To contribute to the knowledge and to update the information on the birdlife in this area, we evaluated the inter-annual variation of the abundance and species richness of birds along the coastline of Isla del Carmen from 2012 to 2016 using survey transects on the shore and nearby urban areas. We recorded 137 bird species, from which more than half (56%) are considered migratory species, and 3% are exotics. Some of the recorded bird species, considered winter visitors, showed signs of reproductive activity, as evident reproductive plumage was observed during the local breeding season for more than one year, including seven species considered winter visitors. There was significant inter-annual variation in bird diversity and abundance, which may be linked to human activities and or coastal erosion processes. Twenty-three out of the 137 avian species recorded are first time reports in this area. The results presented here contribute to updating the knowledge on the resident and migratory avian community in the southern Gulf of Mexico, as well as on the distribution of bird species of international concern.