A joint analysis of all aquatic bird species would give only a hazy picture of biogeographical trends. For this reason, the research team from Malaga divided up the birds of continental Europe, British Isles and Iceland into groups of birds known as ‘corotypes’ (indicators relating to the species’ response to their environment) in order to better understand the historical and ecological processes governing their territorial preferences.

The study, which has been published recently in Global Ecology and Biogeography, divided the distribution of 140 nesting aquatic birds into nine corotypes. “Three of these account for 70% of the species and are very widely distributed throughout the northern regions, southern regions and the middle latitudes of the European continent,” Raimundo Real, lead author of the study and a researcher in the Science Faculty of the UMA, told SINC.

The remaining corotypes are geographically restricted and are located in Iceland, on the edges of Arctic Europe, in the Iberian Peninsula and south eastern Europe. According to the researcher, “ten marine species coincide geographically on the United Kingdom, although they are also distributed along other European coasts and superimpose each other in a gradual way”.

The birds of the Arctic could disappear

The results of the study show that, from an environmental point of view, the climatological temperature (or environmental energy) is the determining factor behind the geographic position of most of the corotypes. “Almost 40% of these species tend to nest in areas with lower temperatures, while a further 40% occupy areas with intermediate levels of environmental energy,” says Real.

The conservation of Europe’s aquatic birds could be compromised by probable global warming. “An increase in temperatures could have the knock-on effect of making the northern species move further north, while eastern species will move further south, and there will be a geographic readjustment among the southern and central European species,” the scientist points out.

Reproductive populations of species with nesting areas close to the Arctic “could even disappear from the continent”, adds Real.

By monitoring aquatic birds that inhabit marshes, wetlands, fresh water or salt water, coastal waters and 55 river basins, it has also been possible to show that water availability, climatic seasonality, availability of resources and the size of the area inhabited are all secondary factors when it comes to explaining the distribution of these species in Europe.

A historical explanation for the dispersion of aquatic birds

The group also suggests that the recent effect of glaciations in the Quaternary Period (from more than 2.5 million years ago up until the present) and the high mobility of aquatic birds could provide a historical explanation for the wide distribution of these species. The fact that some birds from the more geographically restricted groups in Europe are highly dispersed and can be found beyond the continent indicates that only those animals that are highly mobile were able to overcome the harsh weather conditions that existed thousands of years ago.

Note: If no author is given, the source is cited instead.

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