White Storks Stay Put and Eat Junk Food Instead of Migrating

White storks found in Portugal and Spain used to all migrate south to Africa for the winter, but now many are sticking there year-round, sustained by food from landfills. Vasily Fedosenko/REUTERS

The storks, they are a-changin'.

It used to be that all the white storks that breed in Portugal and Spain migrated to North Africa during the winter to find food. But now, many seem to be sticking around.

Milder winters, driven by anthropogenic climate change, as well as the spread of invasive red swamp crayfish (Procambarus clarkii)—a new favorite food—have certainly played a part in the failure to migrate.

But a new study has confirmed that many of these animals are subsisting largely on food from landfills, allowing them to stay put.

In the paper, published March 15 in the journal Movement Ecology, a research team led by the University of East Anglia attached GPS trackers to 48 white storks (Ciconia ciconia). They found that these animals often situated their nests near the landfills, frequently flying back and forth between the two. Others flew up to 30 miles between their nests and landfill sites.

Along with the change in migration habits, the populations of these animals have increased dramatically. In 1995, there were only around 1,200 overwintering storks (overwintering birds are those that do not migrate), while in 2014, there were approximately 14,000. But some storks still migrate, and in fact, numbers of storks seen migrating over the Straits of Gibraltar have increased as well, growing 86 percent between 1985 and 2004, according to the study.

But the birds' free lunches aren't going to last forever. According to National Geographic, the European Union plans to cover over open-air trash piles by 2018 and mandate that new food waste be deposited under the surface. This could lead to the decline of stork populations, or cause them to revert to migrating to North Africa, the study noted.