Climate change ‘forcing predators to move into Arctic nesting grounds’, pushing endangered shorebird species towards extinction
'The Arctic... is no longer a safe harbour for breeding birds'
Shore-dwelling birds like plovers and sandpipers are under threat as global warming leaves their nests vulnerable to thieving predators hunting for eggs.
However, a new study has shown that rates of egg theft in the Arctic have increased threefold in the last 70 years as polar temperatures rise and predators move north.
Over the same period, nest predation doubled in northern regions across Europe and North America.
"The Arctic, with recently elevated rates of nest predation, is no longer a safe harbour for breeding birds,” said doctoral student Vojtech Kubelka, who led the study.
Past research has shown that adult shorebird survival has also decreased in recent years as their habitats are destroyed or they are targeted by hunters.
The combined effect of fewer chicks hatching and more adults being killed has had a devastating effect on population numbers, with some species now critically endangered.
Besides predators moving into new northern territories, the researchers suggested that their diets may be shifting to include more eggs as regular food sources such as lemmings dry up.
Numbers of these small polar rodents have crashed in recent years as rising temperatures makes their snowy habitat less reliable.
"The Earth is a fragile planet with complex ecosystems, thus changes in predator-prey interactions can lead to cascading effects through the food web with detrimental consequences for many organisms thousands of kilometres away,” said Professor Tamas Szekely, one of the study’s authors from the University of Bath.
Rates of nest predation are known to be higher in tropical regions, which explains why so many birds are willing to migrate so far north to find safe breeding grounds.
To understand changes in nest predation over the decades, Mr Kubelka and his team analysed a massive dataset including over 38,000 individual shorebird nests from 237 populations.
The results were published in the journal Science.
Though they acknowledged that the mechanisms behind the egg loss they measured were likely complex, there was a particularly sharp increase in nest predation in the last 20 years, and they identified climate change as a likely culprit.
Discovering this devastating effect was, according to Professor Szekely, “alarming”.
"This could be the last nail in the coffin for critically endangered species such as the spoonbill sandpiper,” he said.