Nearly 13 kilometres per year: that is the rate at which the wintering area of Bewick’s swans has shifted east over the past 50 years. It’s a discovery with consequences for the conservation of this migratory species, writes a team of researchers led by the Netherlands Institute of Ecology (NIOO-KNAW) in Global Change Biology.
Why are Bewick’s swans, a protected species, declining sharply in Ireland and Britain? And to a lesser extent also in the Netherlands, their main wintering area? “This decline in North-West Europe was not consistent with our data on breeding success and survival,” says NIOO animal ecologist Rascha Nuijten. “That’s why we started this research.”
The first indication the researchers had was that in Germany the number of wintering swans was actually increasing rather than declining. To find out more, an international team was formed that also included members from Estonia and the United Kingdom (Wildfowl & Wetlands Trust). MORE
Header image: The research was only possible because of the code some swans carry. Sightings of these tagged animals — often by citizen scientists — offer insight into the whereabouts of individual swans and changes therein. In winter, the swans favour areas with an air temperature of 5.5 °C. Credit: Bart Nolet/NIOO-KNAW.