Vicious isn’t really the right word. Their name comes from the Aztec word for trickster and it’s fair to say that coyotes are cunning and adaptable. They are a major predator of livestock in the US, killing more sheep and cattle than wolves. But that’s simply because they are a lot more common. Any given wolf kills 20 times more livestock than a coyote. Urban coyotes scavenge through bins and kill domestic cats, but the rare attacks on humans are more likely to be from coydogs, which are dog/coyote hybrids, and have lost some of their instinctive fear of humans.