Changing Climate Impacts Water Bird Migration in Britain and Ireland

Birds may have found a better place to be in Britain and Ireland. It turns out the largest lake in this region, Lough Neagh, has lost more than three quarters of its overwintering water birds, revealing that various species may be turning elsewhere as environmental conditions change. The findings show the impact of a shifting climate.

The ecosystem of the lake has dramatically changed since the year 2000. More specifically, scientists discovered that there was a huge decline in the numbers of insects and snails in the lake. This, in turn, was associated with a decline of algae. Water birds that migrated from Northern and Eastern Europe to spend the winter months on the lake depended on these invertebrates. Without them, though, the birds sought out other locations.

"Historically the lake was heavily affected by organic pollution as a result of nutrients from agricultural run-off," said Irena Tomankova, one of the researchers, in a news release. "This artificially boosted its productivity. Now that conservation schemes are beginning to have an effect and reduce levels of pollution we are seeing increasing water quality and the unexpected consequences is fewer invertebrates and as a result less duck food."

Yet there's another reason for the water birds' disappearance from the lake. An associated study showed that numbers of some key water bird species declined throughout southwestern Europe at the same time as numbers dramatically increased in northeastern Europe. The reason was that the winter temperatures in Northern Europe have increased by 3.8 Celsius in the past 30 years. This means that lakes that used to be frozen over in winter are now available for the birds to use. This means that it's likely that the birds that used to winter at Lough Neagh are now seeking lakes that are closer to their natural breeding grounds.

"It is critically important for conservationists and policy makers to understand the reasons behind the dramatic changes that have been recorded at Lough Neagh," said Ian Enlander form the Northern Ireland Environment Agency in a news release. "This work has been an outstanding contribution to improving our knowledge for this site. It underlines the need for international conservation measures to apply across the entire range of these migratory species."

The findings are published in the journal Freshwater Biology.