These white storks are taking addiction to junk food to a whole different level as they're willing to make the 100-kilometer (64-mile) journey to landfills in Portugal and Spain in order to feed on anything edible from the pile.
In a study featured in the journal Movement Ecology, researchers from the University of East Anglia (UEA) in the United Kingdom discovered that an increasing number of the birds have been forced to changed their migratory behavior as a result of drastic changes in their environment as well as influences from human populations.
Many white storks are now choosing to forgo their annual trip from Europe to Africa during winter in favor of staying in landfills where they can easily pick off whatever they can eat from the junk.
With several landfills set to be closed down as mandated by the European Union's Landfill Directives, however, experts believe this could severely affect populations of these migratory birds.
Dr. Aldina Franco, a conservation ecologist from UEA and lead author of the study, explained that the recent population boom of stork populations in Portugal over the past two decades provides researchers with an opportunity to study the animals' migration.
Some species of these birds, such as the white stork, appear to have started resident populations in the country and abandoned their migratory ways around Europe.
Franco said they want to get a better understanding on the causes and mechanisms that triggered such as drastic change in the birds' migratory behavior.
She pointed out that when they examined the reliance of white storks on food available in landfills, they found that it has impacted different facets of the birds' life including their use of nests, how far they travel every day and the ranges they typically go on in search of food.
Landfills Serving As New Homes For White Storks
To monitor the white storks' behavior, Franco and her colleagues placed GPS tacking devices on 48 birds that transmitted their locations five times a day. These trackers allowed the researchers to gather detailed information regarding the stork's behavior.
The GPS devices were developed by UEA researchers together with their counterparts from the British Trust for Ornithology (BTO) and the University of Lisbon in Portugal.
The team discovered that the birds are now reliant on food typically found in landfills, especially when they cannot find enough food sources during their non-breeding season. This led them to start resident populations in areas where these landfills are located.
These landfills also allow the white storks to establish nests that would last all year round. Some birds even use this newfound ability to start their breeding on an earlier date than usual.
The researchers said that having their nests nearby has also given the birds an opportunity to forgo their migration during winter. Instead of making the trip to other areas during their non-breeding season, they spend the time defending their chosen nest locations.
There is also evidence that suggests that the some white storks are even willing to fly some 48.2 kilometers (about 30 miles) during non-breeding seasons and 28.1 kilometers (17.5 miles) during breeding seasons just to go to landfill sites. The research team said these distances are much greater compared to earlier estimates.
Franco and her colleagues expressed their concern, however, about the impending closure of landfills in Portugal as part of the new landfill directives from the EU. New facilities will be established in place of these dump sites where food waste will be processed under cover.
The researchers believe this could force the white storks to look for another source of food during winter, causing them to drastically change their distribution, breeding location and other migratory behavior once again.
