The human impact on the natural world has now also been spotted in the changing behavior of white storks.
Researchers say that the normally migratory birds have given up on moving from Europe to Africa during winter. Instead they are content to stay in Spain and Portugal for the whole year, sustaining themselves on a diet of human landfill waste..
White storks winter in southern Europe rather than Africa
“Landfill sites provide abundant food resources that are reliable in both space and time, thus likely contributing to enabling individuals to remain in their breeding territory and on their nests year-round,” the team of British and Portuguese researchers explain in their study, which was published in the journal Movement Ecology on Tuesday.
There is so much easily accessible food at landfill sites that there are now 10 times more storks in Portugal than there were twenty years ago. The increased population now lives in country for 12 months of the year.
“We found that the landfill sites enable year-round next use, which is an entirely new behavior that has developed very recently. This strategy enables the resident birds to select the best nest sites and to start breeding earlier,” lead researcher Aldina Franco, from the University of East Anglia’s School of Environmental Sciences in Norwich, England, said in a press release.
Changing behavior may give breeding advantage
Dr Franco believes that storks which do not migrate may also have a breeding advantage. They are already in place when mating season begins.
“Having a nest close to a guaranteed food supply also means that the storks are less inclined to leave for the winter. They instead spend their non-breeding season defending their highly desirable nest locations,” said Franco.
However it is not the convenience that brings storks to landfill sites, they are actively looking for them and the scraps of human food found there. Another interesting point is that the storks aren’t necessarily living nearby, but are willing to commute to their food source.
Landfill renovations could impact storks
By placing GPS trackers onto 48 birds, Franco and her team were able to determine their location at 5 times during the day. The researchers found that storks would fly up to 30 miles to a landfill during non-breeding season, and 17 miles during breeding season.
“You see some individuals go from the nest to the landfill site and then just go back to the nest,” Franco told National Geographic.
Another boon for the birds is that alongside an easy source of food, they get to enjoy better weather during the winter. Much like humans, it seems that storks are partial to spending time in Spain and Portugal during mild winters which continue to get warmer due to climate change.
These warmer European winters also make storks traditional food source, red swamp crayfish, more abundant and accessible. However just as human actions changed the storks migration patterns, it seems as though the food bounty is about to end.
Under the new European Union Landfill Directives, every landfill site that has open-air piles will be shut down by 2018. Portuguese authorities are currently working on renovations which will cover the landfill sites and make them inaccessible to birds.
Researchers claim that research is needed into white storks addiction to human waste as a source of food. because landfill renovations could impact population levels in the future.