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Anyone who has wondered at the increasing sight of white storks wheeling in the Algarve skies now has an answer. In two words, it is “junk food”.
A new study suggests storks are “skipping their annual migration to traditional wintering grounds in Africa, opting instead to feast year-round on ‘junk food’ in the landfills of Spain and Portugal”.
The loosely-applied term is used to mean rubbish of all kinds, and show how much “human influences and global changes” are affecting the lives and behaviour of migratory species.
In this study – coordinated by the University of East Anglia in collaboration with university conservation departments of Lisbon and Porto – researchers had to track storks through mountains of garbage on various landfill sites in the south and central Iberian peninsula
Rubber lassos were used to catch the birds and apply GPS trackers to their backs.
Co-author of the resulting paper Dr Aldina Franco has said the research was no picnic.
Those involved “couldn’t eat” while working, as the smell from the landfills was just so bad. But the storks were unphased.
As Dr Franco explained, the landfills allowed them to stay in their breeding grounds “because they now have a fantastic, reliable food source all year round”.
In the Algarve, anyone in the Monchique / Silves / Portimão areas will know how many storks have appeared since the Aterro Sanitário do Barlavento opened in 1998.
“Portugal’s stork population has grown 10-fold over the last 20 years”, the study confirms, adding it is “now home to around 14,000 wintering birds and numbers continue to grow”.
The study tracked 48 birds for around nine months, seeing how far they were prepared to fly from nests to landfill.
“Some travelled as far as 30 miles”, said researchers, with ‘favourites’ on storks’ menus being “rotten fish, leftover chicken and hamburgers”.
Birds were also seen “munching on computer parts and bits of paper”. One was found “with a pair of old, dirty jeans wrapped round its beak”.
But as landfills everywhere reach their capacities, and the EU “plans to start closing” the ones in Portugal, switching to composting factories in 2018, “feeding frenzies might come to an end very soon”, Dr Franco suggests – which means storks may well return to their migratory patterns, or seek out another form of “dump truck buffet” elsewhere.
Only time will tell.
