ON A snowy trail that cuts around the trees is a neat line of paw prints which look as though they were made by a domestic dog. But Heidi Garbe, a research scientist with the Max McGraw Wildlife Foundation, can tell that they were made by a special kind of dog: Canis latrans, the coyote. Its footprint is more oval and its tracks more linear than those made by any household pet.
Around 2,000 coyotes are reckoned to live in Chicago and its suburbs, and it seems likely that the animal is thriving in many other built-up parts of the country. Once restricted to the south-western United States, it spread across the continent during the 20th century and more recently made its way into large metropolitan areas such as Los Angeles, Boston and even New York. In 2010 a particularly intrepid specimen was caught in a parking lot in Tribeca, a trendy neighbourhood in Manhattan.

In Chicago, the Cook County Coyote Project has been trying to understand how the species is conquering the metropolis. Part of the answer is that the coyote is clever, extremely adaptable and reproduces quickly. They are opportunistic eaters and will eagerly consume rabbits, rats, Canada geese, fruit, insects and family pets. They may also be filling an empty niche for a top predator that was once filled by wolves.
Scientists on the project are also trying to investigate how the urban animals differ from their rural cousins. For example, the city slickers have smaller territories, live at higher densities and live for longer than their rustic cousins. Such discoveries suggest that the coyote is probably thriving in American cities rather than clinging on at its edges.
In rural America the coyote remains strongly disliked—partly because it attacks livestock—and is often hunted or trapped. By contrast, urban America is developing quite an affection for the animal. In February a hunting contest in Modoc County, California, drew thousands of complaints to the authorities (it went ahead anyway).
Coyotes rarely attack humans. Between 1960 and 2006 there were only 159 reported cases of bites across North America. By comparison in 2012 there were 5,000 reported bites by domestic dogs in Cook County, which contains Chicago, alone. Nonetheless, in 2009 a young woman was killed by coyotes while hiking in Nova Scotia; scientists do not understand why. One suggestion is that the animals found in eastern America are a coyote-wolf hybrid that hunt more frequently in packs and can take down larger prey.
In America's cities the key to the coyote's success is its virtual invisibility, and sightings of the animal during the recent mating season were unusual enough to have been the subject of news reports. This is no accident. Those who watch the beasts say that the coyote is more nocturnal when it lives in cities than when it is in the wild, which has undoubtedly helped its quiet conquest of parts of metropolitan America. Most people do not actually know they have coyotes living in their neighbourhood, says Ms Garbe, and conflicts only arise when an individual becomes a problem—perhaps having developed a taste for kitchen scraps or possibly Tiddles the cat. Once known as the "ghosts of the plains" coyotes are increasingly known as the "ghosts of the cities". But as long as they stick to the shadows their future looks secure.