Thanks to widespread pet vaccinations, effective post-exposure treatment and the relative rarity of undetected bites by rabid animals, the number of human deaths from rabies in the United States caused has declined to an average of only one or two per year—far less than the number of human...

On a Sunday evening in June, camo-clad men chat and laugh by pickups next to a restaurant near Billings, Montana. There is a faint but unmistakable odor of decay coming from a large trash bin across the parking lot—the just-weighed bodies of 29 coyotes, some of them rotting for two days in 90-degree...