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Characterization of a seabird colony in Bona Island, Panama, and evaluation of drivers influencing the productivity during breeding season 2023-2024

par Melchiori, Silvia
Promoteur Giacomo, Santini
Co-Promoteur Guzman, Hector M.
Publication Non publié, 2024-08-29

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Résumé :

In the Eastern Tropical Pacific, nutrient-rich upwelling waters benefit seabirds by enhancing prey availability during their breeding season, thereby improving breeding success. In 2023-2024, an El Niño event was anticipated to affect the equatorial Pacific, potentially reducing upwelling intensity and altering food availability, which had previously caused dramatic ecological consequences for seabirds. This study evaluates seabird breeding patterns on Bona Island, Gulf of Panama, during 2023-2024 and compares them with surveys from 2017-2018 and 2018-2019, years without strong El Niño, and examines links with oceanographic conditions. Local sea surface temperature, chlorophyll-a concentration, and primary productivity were compared among the study years. Breeding numbers of Brown Pelican (Pelicanus occidentalis) and Magnificent Frigatebird (Fregata magnificens), and breeding performance of Brown Booby (Sula leucogaster) and Brown Pelican were measured through field assessments and drone surveys. Oceanographic conditions did not show significant differences between years, limiting the ability to directly correlate them with seabird population trends. The lack of interannual differences in Brown Booby breeding performance suggests no dramatic effects from El Niño on this species, despite overall low reproductive success. Brown Pelican breeding numbers remained consistent, with high fledging success, indicating a healthy colony. In contrast, Magnificent Frigatebird numbers declined compared to previous years, highlighting the need for further investigation. This study provides new insights into the interannual seabird breeding patterns in Panama, which have just now been investigated. Future research is needed to fully comprehend colony trends and their relationship to oceanographic changes, informing better policy and management measures.