Seagull chicks raised on an ‘urban’ diet still prefer seafood, new research shows.
Scientists from the University of Exeter studied herring gull chicks rescued after falling from roofs in towns in Cornwall, UK.
They were raised in captivity (before being released) and fed either a ‘marine’ diet consisting mainly of fish and mussels, or an ‘urban’ diet consisting mainly of bread and cat food.
Every few days the seagull chicks were given a choice of all four foods in different bowls, to test which they preferred – and all seagulls strongly preferred fish.
“Our results suggest that even if raised on an ‘urban’ diet of foods only found near people, these chicks are unlikely to forage for urban foods as adults,” said lead author Emma Inzani of the Center for Ecology and Conservation. Exeter’s Penryn campus in Cornwall.
“Human-associated foods are often reliably present and easy to obtain, but if fish is available, they clearly prefer it.”
Herring gulls are often seen as a pest in urban areas, where they scavenge for fallen food and in containers, and sometimes take food from people.
However, the species is on the UK’s list of major conservation concerns due to continued population declines.
Inzani said a combination of reduced fish stocks in British waters – coupled with abundant and easy access to food waste in cities – could mean it is not as profitable for seagulls to spend a lot of energy searching for food in the sea.
Previous research has shown that parent gulls often switch to foraging for more fish once their chicks hatch, possibly because seafood provides more of the nutrients the chicks need to grow.
In this new study, all 27 chicks had access to food all day, but half of the chicks were fed city food and 20% seafood 80% of the day, while the other half of the chicks were fed the opposite diet.
When given all four foods together on days 5, 10, 15 and 35 of the study, both groups consistently preferred fish – and even those who tried the bread rarely ate much of it.
Chicks’ preferences for fish found in this study may reinforce the behavior observed in parent gulls to switch to providing more food from the sea once the chicks hatch.
“Animals can live and exploit urban areas for human food waste,” says senior author Dr. Neeltje Boogert.
“However, this does not necessarily mean that they are doing it right or that they are choosing these foods, rather than making the best of a bad situation.
“More research is needed to investigate how the food young animals are fed affects their later lives, including their food choice, health and reproduction.”
