A new study confirms that white storks are no longer migrating from Europe to Africa, instead opting to stay in Spain and Portugal and feast on human garbage year-round. You're welcome, storks! But also sorry, storks.
The research, published in Movement Ecology suggests that the storks have become dependent on the food they get from landfills. That addiction, plus warmer European winters, have changed the birds' habits altogether. Study co-author Aldina Franco explained in a statement that "Portugal’s stork population has grown 10 fold over the last 20 years. The country is now home to around 14,000 wintering birds, and numbers continue to grow." She added, "we found that the continuous availability of junk food from landfill has influenced nest use, daily travel distances, and foraging ranges.”
To track the storks' behavior, Franco and her team placed GPS devices on 48 birds, and monitored their movement for months. The researchers found that the storks now build their lives around access to trash food, and that their breeding behaviors have changed as a result:
The landfill sites enable year-round nest 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… 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.
The storks don't necessarily settle down right by the landfills, however. Per Franco:
We also show that as well as those nesting close to the landfill sites, others are willing to travel up to 48.2km to visit landfill sites during the non-breeding season and up to 28.1km during the breeding season.
Researchers have noticed the storks' newly non-migratory lifestyle before. Back in January, a study published in Science Advances found that a number of different white stork populations have been affected by manmade changes to the environment. The authors found that storks who have close access to food from landfills and other sources end up saving energy, and might have a better shot at surviving winter than their migratory counterparts. As they wrote in their abstract, "overwintering in areas with higher human population reduced the stork’s overall energy expenditure because of shorter daily foraging trips, closer wintering grounds, or a complete suppression of migration."
But it's still troubling that human behavior has effected so much change over nature — especially because Portuguese landfills are set to be phased out, which will force the storks to once again change their behaviors, or perish. Harsh.
Danielle Wiener-Bronner is a news reporter.