Urban coyotes never stray from their mates.

• Position: Monogamy

Coyotes living in cities do not ever stray from their mates, and stay with each other until death do them part, according to a study published in the Journal of Mammalogy. The finding sheds light on why the North American cousin of the dog and wolf, which is native to deserts and plains, is thriving today in urban areas.

Scientists who sampled 236 coyotes genetically in the Chicago, Ill., area over a six-year period found no evidence of polygamy--of the animals having more than one mate--nor of one mate ever leaving another while the other still was alive. This was even though the coyotes exist in high population densities and have plenty of food to eat, which are conditions that often lead other dog family members, such as some fox species, to stray from their normal monogamy--to cat around, as it were.

"I was surprised we didn't find any cheating going on," admits study coauthor Stan Gehrt, a wildlife ecologist. "Even with all the opportunities for the coyotes to philander, they really don't. In contrast to studies of other presumably monogamous species that were later found to be cheating, such as Arctic foxes and mountain bluebirds, we found incredible loyalty to partners in the study population."

The loyalty of coyotes to their mates may be a key to their success in urban areas. Not only does a female coyote have the natural ability to produce large litters of young during times of abundance, such as when living...