RESUMEN
The Pedregal de San Ángel Ecological Reserve (REPSA) is located within the central campus of the National Autonomous University of Mexico (UNAM), in southwestern Mexico City. This area is known for its bird richness, which has been documented over time. However, this historical information has not been compiled, nor has it been assessed whether species composition has changed over time. In this study, we generated the historical checklist of avifauna in the REPSA by integrating data from systematic monitoring, bibliographic review and citizen science. Additionally, we calculated Jaccard's dissimilarity Index (nestedness and species turnover) among bird checklists from each year and evaluated whether this index and its components changed over time. In addition, we estimate whether the proportion of species arriving and becoming extinct in the REPSA is influenced by time (census interval) and by the migratory status of the species. Finally, we identified the core species of the REPSA. Our results indicate that from 1967 to 2023, 258 bird species have been recorded in the REPSA. The Jaccard's dissimilarity and turnover increased and reached an asymptotic trend over time while nestedness showed similar values throughout time. The time and species residency status did not have significant effect on the proportion of species that arrival and become extinct in the reserve. We identified 58 core species based on their persistence; 35 of these are residents, 22 have some migratory movement and one exotic species. Our results highlight the importance of the REPSA as a fundamental habitat for the avifauna of Mexico City, including a wide variety of migratory bird species.