Since the mid-1980s, the number of storks migrating from Europe to northern Africa has fallen drastically. While thousands of storks once made their way to Africa to spend the winter, the number doing so has dwindled since the 1980s. Scientists suspect the white-winged birds have changed their iconic migratory behavior because of growing mounds of garbage.
That is, scientists think that storks have ceased their centuries-old practice of migrating — the reason of the great birds being said to deliver babies according to folklore — is that they have found an easily acquired food source, discarded food from dumps in Spain and Portugal. Storks are “opportunistic and adaptable” and — does it not sound familiar? — have readily made the switch to eating the “junk food” (containing who knows what chemicals and other substances) in landfill heaps.
Aldina Franco, from the University of East Anglia‘s school of Environmental Sciences, notes that the storks’ migratory patterns have changed “radically” and that many storks are now living year-round in Spain and Portugal. Some 1,180 birds wintered in Portugal in 1995, but those numbers grew to over 10,000 in 2008 and have only been going up.
Franco and other scientists from the University of East Anglia are seeking to find out why storks have, in such a short time, changed their behavior. To that end, they have tagged 15 storks caught in Portugal and will be able to track their movements four times during the day and once at night, to learn more about their roosting and feeding habits and the length of their flights. The researchers will be able to know when the storks are feeding because they put their heads down when foraging for food.
The garbage dumps provide an “abundant and reliable food supply ,” says Franco, though some of the birds seem to be feeding in them more than others. Understanding why so many storks are staying in one place is also key to predicting their long-term future.
Researchers will be looking at how climate change could be playing a role in their changing migratory habits. The birds have been breeding in new parts of northern Portugal, possibly because the climate there has become more suitable. The birds’ locations can be tracked daily via the British Trust for Ornithology.
Another factor that is beyond the storks’ control and could play a role in their future feeding is their continued “easy access” to humans’ discards. As Nathalie Gilbert, a doctoral student who is assisting in the research, says many of the landfill sites in Portugal that have been serving as the storks’ food source are “scheduled to be gradually replaced by new facilities where food waste is handled under cover.” It’s a change that could indeed influence the storks’ “breeding location, chick fledging success and migratory decision.”
In the absence of too readily available “free” food, will the white stocks be able to return to their centuries-old ways?
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