Bird communities of the Veracruz Reef System National Park islands

Background. Bird studies in the Sistema Arrecifal Veracruzano National Park (PNSAV) have reported pre-viously that 48 % of the birds are winter migrants and 52 % are residents. However, the structure of the bird communities of its islands has yet to be previously analyzed. Objectives. To analyze the bird communities’ structure of Sacrificios, Verde, Salmedina, Polo, de Enmedio, and Santiaguillo islands. Methods. From April 2021 to April 2022, six bird censuses were conducted on each island. With the data obtained, species rich-ness, abundance, and alpha diversity using the Shannon, Margalef, and Simpson indices, were determined. Additionally, birds were classified into marine, aquatic or coastal, hawks, and terrestrial, and the number of species and the sum of maxima of these groups were calculated for each island. Finally, with all the informa-tion, the conformation of each island’s bird communities and their diversity variations throughout the study year were analyzed. Results. De Enmedio Island had the highest diversity values (April and October 2021). October had the highest diversity values for Sacrificios, Verde, and Santiaguillo islands. Salmedina and Polo showed the highest diversity in July 2021 and January 2022; only marine and coastal birds were observed on these two islands; in the other islands, terrestrial species predominated. On Polo Island, marine birds were highly abundant despite the island’s small size. Conclusions. There appears to be great anthropogenic pressure on seabirds’ resting and breeding habitats. There needs to be more information about the islands, and generating it is relevant for the integrated management of the PNSAV