An article in Scientific American says that contrary to earlier studies, coyotes are monogamous throughout their lives:
Beyond the ferocious jaws of the carnivorous coyote is a loving creature that scientists say is 100-percent monogamous. Researchers studied the mating patterns of two hundred thirty six coyotes in the Chicago area over a six-year period. They found that coyotes living in urban areas are faithful to their partners, and stay with them for life. The research is in the Journal of Mammalogy. [Cecilia A. Hennessy, Jean Dubach AND Stanley D. Gehrt, Long-term pair bonding and genetic evidence for monogamy among urban coyotes (Canis latrans)]
Scientists collected blood and tissue samples of coyotes and equipped some adults with radio-collars before releasing them all back into the wild. Genetic analyses showed no evidence of polygamy within the urban coyote population, and consequent studies of their movements showed that pairs stayed together through multiple breeding seasons.This finding is noteworthy since it shows that not all animals, humans being one of the exception, are interested in sexual adventures. Coyotes are faithful, and the reasons why this is so requires further study. As Amy Kraft writes: "It was thought that coyotes would be more likely to stray from a mate in an urban environment where food and females are plentiful. Instead, the research provides evidence that not all species of canids are dirty dogs."
You can read the rest of the article at [Scientific American].