Landfill foraging may have long-term health consequences for white storks

Society for Experimental Biology

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White storks foraging on a landfill.

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Credit: Anustup Bandyopadhyay

Ongoing research into the impact of landfill foraging on white stork populations has revealed interesting preliminary results that suggest a trade-off between year-round reliable food availability and increased risks from stress and DNA damage. These results provide insights into how human urbanisation is rapidly altering the feeding behaviours of wildlife with possible long-term consequences for their health and fitness.

“The globally increasing trend of waste production is creating new foraging opportunities for wildlife,” says Mr Anustup Bandyopadhyay, a PhD student at the University of Veterinary Medicine in Vienna, Austria. “However, the effects of feeding on this waste are still debated and remain somewhat equivocal.”

This project is an international collaboration involving researchers from Austria, Germany, and Poland that focuses on a population of White storks (Ciconia ciconia) that migrate from Poland to Africa each summer and return each spring to breed.

White storks have been observed foraging on landfills in Western Europe since the 1980s, but it is still a relatively new phenomenon in Eastern Europe. “In Poland, this behaviour has become more common over the past decade, with some individuals relying on landfills while the majority still rely on natural prey,” says Mr Bandyopadhyay. “This provides a good system to examine how different foraging strategies translate into differences in growth, energy balance, and physiological condition.”

When white storks feed from landfill, they ingest a mix of human food waste that includes meat, small insects, rodents and earthworms. However, they may also ingest solid waste materials such as plastics, wires, glass and harmful heavy metals.

Landfills are attractive to storks because they provide a reliable food source that is energetically cheap to forage and available all year. “They can spend less time foraging and potentially channel that time and energy into other activities such as breeding,” says Mr Bandyopadhyay. “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.”

Although landfills provide this readily available source of food, this project, presented at the Society for Experimental Biology conference in Florence, Italy, highlights how the low nutritional quality and potential increased exposure to contaminants from landfill foraging may be affecting their physiology and behaviour.

To measure the effect of landfill foraging on the storks’ physiology, Mr Bandyopadhyay uses a variety of techniques including enzyme immunoassays for hormones, colorimetric assays for oxidative stress and high-resolution respirometry to study mitochondrial metabolism. Together, these help the researchers to track the development and fitness of young storks growing up on contrasting nutritional conditions.

With his collaborators in Poland and Germany, Mr Bandyopadhyay uses body measurements and high-resolution tracking to better understand the impact of landfill foraging on life-history traits, migratory behaviour, and the energetic costs of foraging in different habitats.

Preliminary results from Mr Bandyopadhyay’s Polish collaborators reveal that landfill-foragers tend to have a greater body mass and higher energy stores than those that feed on natural prey. However, they have also found evidence of DNA damage associated with landfill diets appearing much sooner than expected.

“We expected to see DNA damage linked to diet at the end of their nestling stage, but instead we observe that these differences appear at a very early age, when the birds are only about a week old,” says Mr Bandyopadhyay.

As well as affecting stork physiology, the reliability of food offered by landfills may now start influencing their migratory behaviours, as seen in other populations. “The Iberian Peninsula white storks have shifted from being wholly migratory to partially migratory, or even sedentary, largely due to favorable weather conditions and, importantly, the availability of landfill food subsidies,” says Mr Bandyopadhyay.

This project is funded by the Austrian Science Fund (FWF) and more details about the project’s funding can be found here.

Contributing authors: Anustup Bandyopadhyay¹, Nitya Triveillot², Atharva Andhare³, Joanna T. Białas², Marcin Tobółka², Andrea Flack³, Valeria Marasco¹.

Institutions: ¹ University of Veterinary Medicine Vienna, Vienna, Austria. ² Poznań University of Life Sciences, Poznań, Poland. ³ Max Planck Institute of Animal Behavior, Konstanz, Germany.

Pair of white storks.

Credit

Anustup Bandyopadhyay