AUGUST 26, 2019
Crows living in urban environments with access to discarded human food have higher blood cholesterol levels than their rural cousins. Credit: Andrea Townsend
Animals that do well in urban areas tend to be the ones that learn to make use of resources such as the food humans throw away. But is our food actually good for them? A new study published in The Condor: Ornithological Applications suggests that a diet of human foods such as discarded cheeseburgers might be giving American Crows living in urban areas higher blood cholesterol levels than their rural cousins.
Hamilton College's Andrea Townsend and her colleagues sampled the blood cholesterol levels of 140 crow nestlings along an urban-to-rural gradient in California, returning to track their survival rates after they fledged. They found that the more urban the environment, the higher the blood cholesterol of the crow nestlings raised there. To directly test the effects of human food, the researchers also provided nestlings in a rural New York population with a regular supply of McDonald's cheeseburgers and compared their blood cholesterol levels with those of nearby crows who had to fend for themselves. The crows who were fed cheeseburgers ended up with higher cholesterol levels than their neighbors, similar to those of the urban crows in California.