Over the course of many years studying endangered San Joaquin kit foxes, retired biology professor Ted Murphy noticed they aren't discerning about food.
"They'll eat practically anything," he said. "I'd find fast food bags, rib bones, almost anything you could think of around the dens.
"They don't tear up a trash bag like a dog does. There's a hole at the precise spot where the turkey carcass is."
It wasn't supposed to be this way. Normally, North America's smallest fox preys on rodents such as kangaroo rats and squirrels, or the occasional pigeon.
But between the loss of their natural habitat to farms and development and predators such as coyotes and birds of prey, kit fox populations are dwindling. Survivors who have been squeezed into urban areas forage for what they can, but their diet of food cast off by humans is catching up to them.
Apparently junk food and processed meals aren't any better for foxes than they are for us. Urban kit foxes in and around Bakersfield are fatter and have higher cholesterol levels than their counterparts in the wild, according to a report published late last year in the Journal of Mammalogy.
Researchers from the University of Wyoming and California State University-Stanislaus analyzed hair samples to get an idea of what both populations were eating and how it was affecting them.
The authors said that approach is a lot better than the traditional method of examining feces, because human food is highly digestible, so there's not much to see at the, er, end.
The effect of mimicking human eating habits varies depending on precisely what foxes are scarfing down, but "If they're eating a lot of Twinkies or doughnuts, that's not good for them, obviously," said Brian Cypher, one of the study's authors and associate director and research ecologist at California State University-Stanislaus.
Urban kit foxes are as much as 20 percent heavier than kit foxes that aren't living around people, and their cholesterol levels are elevated, according to the study.
There are a host of other downsides to living near humans. Kit foxes drawn to trash bins and other places where food is dumped expose themselves to feral dogs, being hit by cars, and other urban threats.
Plus the limited range doesn't allow for as much reproductive diversity, so there's a higher risk of in-breeding that weakens the species over time.
One of the biggest concerns is dependency, said Don Richardson, curator of animals for the Bakersfield animal refuge California Living Museum, or CALM.
"We want them to maintain their wildness, not get dependent on us," he said. "But they're opportunistic feeders. They adapt easily to living in human areas where food is easy to get."
Urban kit foxes are especially fond of school campuses and parks because they tend to have big, grassy fields and there's lots of food around, the report said.
Wayne Van Horn Elementary School in the southwest has had kit foxes scurrying around for years. They're little celebrities on campus, eliciting cries of joy on the rare occasions they emerge when children are present.
"I mostly see them when I come early in the morning," said principal James Lopez. "They don't usually come out if there are kids around."
Kit foxes are native Californians. The average healthy kit fox is about 20 inches long and weighs about five pounds.
Because there are fewer than 1,000 of them left, almost exclusively in the southern San Joaquin Valley, they've been on the endangered species list since 1967.
Murphy, professor emeritus of biology at Cal State Bakersfield, said he noticed Bakersfield's kit foxes were getting chubby years ago when he used to trap and tag them.
Murphy recalled once setting a trap with bait at the end of a large pipe. The last of four foxes that went for it couldn't get to the food -- despite some determined wiggling --because its ample frame wouldn't fit.
"Generally once you had them in a hold so they couldn't bite, they'd sit very calmly while you measured them," Murphy added. "Ordinarily they're five pounds or so, but I had one, I swear this thing was like a big lap dog. It was such a pudgy thing."
The good news is that in spite of the penchant for food of dubious nutritional value, urban kit fox populations are growing faster than populations far from humans.
That makes sense, Murphy said.
"Foxes in the wild have to do a lot of work for not very much food. It's much easier for a fox to make a living here," he said. "They're pretty much domesticated. If you encounter one, they're likely to stand and stare, as opposed to something like a coyote that would run away. And they're darling little animals. I know people who hand feed them."
Indeed, because Bakersfield is one of the few remaining places where you can find a kit fox, the animal has become a sort of unofficial mascot here. Residents look forward to putting food out in places where foxes are known to have a den.
That's illegal, by the way. It's against the law to feed an endangered animal because biologists don't want them ingesting something that might be harmful.
Murphy isn't too alarmed by people feeding kit foxes. He raised some orphaned pups on raw chicken for a bit before setting them free, and they all did just fine.
Researcher Cypher said he knows it's a little unrealistic to expect animal lovers to resist such a cute, hungry moocher.
"If you absolutely can't help yourself, at least buy some pet food," Cypher said. "That will ensure they're getting a balanced diet."