15-11-2024
Migratory differences in Audouin's gulls according to age and future management strategies for this vulnerable species
An IRBio study reveals that juvenile gulls travel further and explore more habitats than adults, highlighting the importance this can have in conservation policies.
Researchers from the Biodiversity Research Institute (IRBio) and the University of Barcelona have published a new study that reveals differences in the spatial ecology of the Audouin's gull (Ichthyaetus audouinii) during the non-breeding season, according to the age of the individuals This work, led by Raquel Ponti and collaborators, has been published in the journal Endangered Species Research.
A longer and exploratory migration of juveniles
The study, based on GPS tracking of juvenile and adult individuals from the colony of San Pedro del Pinatar (Murcia), shows that juvenile gulls travel further distances and all migrate towards the West African coast (Western Sahara, Mauritania and Senegal), while the adults tend to exploit the Moroccan and Saharan coasts, and even remain in the Western Mediterranean during the entire wintering period. According to the last author of the work, Raül Ramos (Seabid Ecology Lab, dept. BEECA, Faculty of Biology), this result would be explained by the purely exploratory behavior in the first stages of life of the migratory and long-lived avifauna, while the adults would opt for more efficient strategies based on accumulated experience. It must be remembered that these species usually live for several decades during which they accumulate many experiences and the expertise necessary to optimize the use of resources throughout the annual cycle.
The results also show that juveniles are less selective in the choice of habitats used, while adults prefer marine, fresh and brackish waters to search for food. This preference for freshwater habitats could be due to the high availability of food resources in these areas. A good example of this is the American red crab, an invasive species that has become an important food source for the Audouin's gull along the entire Mediterranean coast.
Implications for conservation: the need for transnational and differential management
The study highlights the importance of these age differences for the design of effective conservation measures, especially for a species listed as Vulnerable by the IUCN. "Our results provide key information to develop management strategies that consider the specific needs of juveniles and adults during migration," says Jacob González-Solís.
This work highlights the need for transnational and transcontinental management of Audouin's gull migration areas, particularly on the West African coast, where the lack of effective fisheries management policies puts juvenile populations in particular at risk.