White storks in Europe are increasingly turning to landfill sites for food, but new research suggests this diet of human waste may pose hidden health risks, including DNA damage, even as it boosts their body mass and energy stores.
Landfill foraging alters stork behavior and physiology
Once endangered and known for long migrations between Europe and Africa, some white stork populations have shifted their behavior as discarded food becomes easier to find than natural prey. Storks foraging at landfills consume human food waste, meat scraps, insects, rodents, and earthworms, saving energy they would otherwise spend searching across fields and wetlands. However, these sites also expose birds to plastics, wires, glass, and heavy metals.
Anustup Bandyopadhyay, a PhD student at the University of Veterinary Medicine Vienna involved in the study, said growing global waste production creates new feeding opportunities for wildlife, but the consequences for storks remain contested. The researchers presented early findings at the Society for Experimental Biology conference in Florence.
Benefits come with contamination risks
The study focused on white stork populations in Poland, where many birds still rely mainly on natural prey, allowing comparisons. Preliminary results indicate landfill-feeding storks have greater body mass and higher energy stores than those feeding naturally. “They can spend less time foraging and potentially channel that time and energy into other activities such as breeding,” Bandyopadhyay said. “Our partners from Poland have also found that white storks use landfills mostly in the middle of the breeding season, when the food demands of nestlings are at its peak.”
But these benefits come with risks. Researchers detected evidence of DNA damage linked to landfill diets much earlier than expected—in chicks “only about a week old.” The convenience of landfill foraging may also influence migration patterns, as seen in western European populations. Bandyopadhyay noted, “The Iberian peninsula white storks have shifted from being wholly migratory to partially migratory, or even sedentary, largely due to favourable weather conditions and, importantly, the availability of landfill food subsidies.”
Experts weigh the trade-offs
Prof Aldina Franco, an ecologist at the University of East Anglia who was not involved in the research, described landfill food as “junk food” for birds. “It’s food that is rotting and it’s poor quality, and probably highly energetic. So, they can get leftover steaks or leftover fish, everything we throw away to landfill sites.” She added that the picture is nuanced: “It is true that it can be damaging for individual storks to eat these types of food that can have contaminants and diseases. But from a population perspective, if you’d have 500 storks going to a landfill site, maybe a few will die from eating these contaminated items, but the majority will actually benefit from having extra food.”
EU waste policy changes may impact storks
The issue is becoming more urgent as open landfill access declines in Europe due to changes in EU waste management policies. This could affect the numbers, movements, and breeding success of storks that rely on these food sources. Franco said this is a potential concern for white stork populations accustomed to landfill foraging. “On the one hand we are very happy to provide food in our gardens through bird feeders. The landfill sites are waste that we don’t use and the question is, shouldn’t we allow some species to benefit from these resources that we no longer need? The white stork populations were declining until the 1980s. They disappeared from several European countries and now they have been reintroduced in Sweden, and in the UK just recently.” Franco added, “Will the stork populations decline if we completely prevent them from accessing our organic waste? I think that’s a risk and it needs to be thought through.”
