The coyote  , that clever animal of wide-open spaces, has come to the nation's capital. In fact, coyotes have spread to every corner of the United States, changing their behaviors to fit new environments and causing researchers to deal with a troublesome new kind of creature: the city coyote. The coyote originally lived in the middle of the continent. One of its most obvious characters is its smartness, which has made the animal a notorious   pest. Hunters trapped, shot and poisoned more than a million coyotes in the 1900s. It's still one of America's most hunted animals. Yet the coyote has survived. How has the coyote shown this extraordinary ability? "I guess if you wanted to use one word, it'd be ' _ '," says Eric Gese, an expert at Utah State University. Coyotes can live alone, in pairs, or in large packs like wolves; hunt at night or during the day; occupy a small region or an area up to 40 square miles; and live on all sorts of food, from lizards and shoes, to ants and melons. Unbelievably people helped coyotes increase when they killed most of the wolves in the United States. The spreading of coyotes into city areas, though, is recent. They travel at night, crossing sidewalks and bridges, running along roads and ducking into culverts   and underpasses. No one knows why coyotes are moving into cities, but experts explain that cleverer, more human-tolerant   coyotes are teaching urban survival skills to new generations. Occasionally, coyotes might attack human beings. There have been about 160 attacks on people in recent years. Therefore, people have been consistently told not to feed coyotes or leave pet food unsecured. That, plus a large trapping program in the neighborhood, has cut down on the coyote population. According to the passage, to cut down on the coyote population, people are advised to   _  .
leave pet food secured keep coyotes in small regions force coyotes to live alone avoid using trapping programs