By modifying ecosystems, global warming disrupts the distribution and dynamics of species. In this context, migratory waterbirds are particularly sensitive to temperature variations. A recent study, based on 25 years of waterbird observation data from Sweden, examines these complex dynamics, focusing on possible interactions between climate variations and bird habitat characteristics.
This study analyzes the responses of 18 waterbird species to global warming, focusing on the northern limit of their winter distribution ranges. Based on data from 2,982 counts carried out in Sweden over a 25-year period, the researchers used Hierarchical Modelling of Species Communities (HMSC) to examine how winter temperatures and habitat characteristics influence changes in the presence and abundance of these populations.
Overall, this study demonstrates that not all phylogenetic groups of waterbirds are impacted in the same way by climate variations. It also highlights the importance of protected areas and large wetlands for waterbirds during Sweden’s warm winters.
Over the 25 years of data used in the study, winter temperatures rose by an average of 1.29°C at the sites studied. The majority of species responded positively to this increase, with a higher probability of presence and abundance during warmer winters. Indeed, while wetlands are generally frozen during winter in Sweden, warmer temperatures create potential habitats for waterbirds. The species most responsive to rising temperatures are those with the warmest thermal niches.
- The occurrence and abundance of waterbirds is positively related to the size of the site and its protection status within the Natura 2000 network. For 60% of species, this positive occurrence and abundance is even more significant during the warmest winters.
- The interaction between higher winter temperatures and the abundance of species known to frequent urbanized areas is mainly negative. These results could be explained by three non-exclusive hypotheses: 1) some species may benefit from urbanized surfaces during cold winters due to an urban heat island effect; 2) if urban wetlands are less likely to freeze, running water may be more abundant there; or 3) additional food inputs (e.g. feeding ducks in the city) may improve the availability of food resources for some dabbling ducks, particularly in cold winters.
- Sites surrounded by agricultural land are particularly attractive for species known to graze on fields, such as Greylag Geese (Anser anser), Harvest Geese (A. fabalis), White-fronted Geese (A. albifrons) and Whooper Swans (Cygnus cygnus).
This study shows that in Sweden, changes in the occurrence and abundance of waterbirds in response to rising winter temperatures were impacted by the type of habitat concerned, resulting in a stronger or weaker response to temperature. In this sense, the authors of the study conclude that conservation strategies aimed at improving the response of waterbirds to global warming by facilitating their changes in distribution must include the protection of natural habitats, the restoration of degraded wetlands and the rewilding of surrounding areas.
Référence bibliographique
Gaget E., Ovaskainen O., Bradter U., Haas F., Jonas L., Johnston A., Langendoen T., Lehikoinen A.S., Pärt T., Pavón-Jordán D., Sandercock B.K., Soultan A., Brommer J.E. Changes in waterbird occurrence and abundance at their northern range boundaries in response to climate warming: importance of site area and protection status. Animal Conservation [Internet] [cited 2024 Nov 6]. doi: 10.1111/acv.12998
Contact
Elie GAGET – Research scientist – statistical ecology
E-mail | +33 (0)4 90 97 29 78
