But all the fast-food scraps that city crows are eating may be increasing their cholesterol levels, according to a new study published in bird journal The Condor: Ornithological Applications.
Researchers came to the conclusion after comparing the cholesterol levels of 140 crow nestings in rural, suburban and urban areas near Davis, California, as well as the birds’ body mass, fat reserves and survival rates, according to New Scientist.
Turns out, the more urban the bird, the higher its blood cholesterol level.
The researchers then decided to see if cholesterol levels were higher in birds with ready access to fast food ― the type of diet known to raise levels in humans. To do that, they left a feast of up to 100 McDonald’s cheeseburgers at a time near crow nestings in rural Clinton, New York.
The burgers went over big with the birds, and some gobbled as many as three a day. Other adult crows would bring home burgers to their nestlings or store them for later, according to NationalGeographic.com.
Although the burger-eating birds did have higher cholesterol levels than the crows that didn’t eat Mickey D’s, researchers found no correlation with survival.
In addition to diet, the researchers noted that urban crows face other factors that may make their lifespan shorter than rural crows, including car collisions, predators and disease.
However, lead researcher Andrea Townsend did note that birds eating burgers had better body condition than the rural crows. Townsend, an ornithologist at Hamilton College in upstate New York, emphasized that just means they weighed more than typical crows.
“If you’re a chubby crow, essentially, that’s considered to be good condition,” Townsend said, according to NationalGeographic.com.
And while high cholesterol isn’t good for human health, Townsend noted that it can be an asset for a crow.
“It’s an important part of our cell membranes and a component of some crucial hormones,” Townsend said, according to Science Daily. “We know that excessive cholesterol causes disease in humans, but we don’t know what level would be ‘excessive’ in a wild bird.”
Townsend was quick to add that there is no good reason to replace bird seed in backyard feeders with Quarter Pounders or Whoppers.
“Wild birds haven’t evolved to eat processed food, and it might have negative consequences that we didn’t measure, or that will only show up over longer periods of time,” Science Daily quoted Townsend as saying.