to do the same. Conservation status Ecologists consider this rodent to be a keystone species. They are an important prey species, being the primary diet in prairie species such as the black-footed ferret, swift fox, golden eagle, red tailed hawk, American badger, coyote and ferruginous hawk. Other species, such as the golden-mantled ground squirrel, mountain plover, and the burrowing owl, also rely on prairie dog burrows for nesting areas. Even grazing species, such as plains bison, pronghorn, and mule deer have shown a proclivity for grazing on the same land used by prairie dogs. Nevertheless, prairie dogs are often identified as pests and exterminated from agricultural properties because they are capable of damaging crops, as they clear the immediate area around their burrows of most vegetation. As a result, prairie dog habitat has been affected by direct removal by farmers, as well as the more obvious encroachment of urban development, which has greatly reduced their populations. The removal of prairie dogs "causes undesirable spread of brush", the costs of which to livestock range may outweigh the benefits of removal. Black-tailed prairie dogs comprise the largest remaining community. In spite of human encroachment, prairie dogs have adapted, continuing to dig burrows in open areas of western cities. One common concern which led to the widespread extermination of prairie dog colonies was that their digging activities could injure horses by fracturing their limbs. However, according to writer Fred Durso, Jr., of E Magazine, "after years of asking ranchers this question, we have found not one example." Another concern is their susceptibility to bubonic plague. the U.S. Fish and Wildlife Service plans to distribute an oral vaccine it had developed by unmanned aircraft or drones. In captivity Until 2003, primarily black-tailed prairie dogs were collected from the wild for the exotic pet trade in Canada, the United States, Japan, and Europe. They were removed from their burrows each spring, as young pups, with a large vacuum device. They can be difficult to breed in captivity, but breed well in zoos. Removing them from the wild was a far more common method of supplying the market demand. They can be difficult pets to care for, requiring regular attention and a very specific diet of grasses and hay. Each year, they go into a period called rut that can last for several months, in which their personalities can drastically change, often becoming defensive or even