The white stork used to be famous for spreading its black-tipped wings and migrating vast distances. Colloquially called a “long-distance migrant”, it travels with the changing seasons, choosing the warmest place to nibble and make babies.
A European by birth, the bird wanders as far south as South Africa to get away from the chilling ice of its homeland’s winter. It’s this desire to go places that has put storks at the centre of baby-making folklore: they’re the birds wandering over cities with swaddled babies suspended from their long beaks, trying to work out who ordered which child.
But new research shows that storks are no longer going far for food and warmth. A team from the University of East Anglia followed 48 storks by using GPS tracking devices. These beamed the bird’s location back to the university five times a day. The picture that emerged was of a bird that no longer travels across the world, but that has adopted a sedentary lifestyle instead.
When the results were tracked to places, it turned out that the storks spent much of their time wandering around landfill sites. Here, a steady supply of readily available junk food meant they needed to expend little effort to forage.
The research team, releasing their results in the journal Movement Ecology, said: “The bird is among a growing number of migratory species that have changed their behaviour due to human influences and global environmental change.”
Not having to migrate halfway across the world in winter means the birds save on energy, the East Anglia team said. They also get good nesting sites and can start breeding earlier. “This gives them bigger broods and a better survival rate for their chicks.”
As a result, their population numbers are exploding. Portugal, where many of the GPS-tracked storks live, has had a tenfold growth in its stork population in the past 20 years. In winter, 1 000 storks now congregate on the small European country, rather than heading south.
Although the competitive advantages are clear, the team also found that storks were still willing to travel – for more junk food.
Several of the tracked birds flew up to 48km to visit other landfill sites to get a takeaway.
But their feasting will be short-lived. Just as they hunker down to a sedentary lifestyle and tasty treats, storks are now faced with a series of European Union “landfill directives”. These will close open landfills across the continent in favour of ones with covering, so that birds cannot become reliant on the food.
This might force the storks to take flight in search of organic food once again – unless they move south again and find themselves snacking on South African landfills.