Killer Prairie Dogs Make the Best Moms
Monster Monday—
June 6, 2016
Prairie dogs may look cute to humans, but some are cold-blooded killers. Scientists John L. Hoogland of the University of Maryland Center of Environmental Sciences and Charles R. Brown of the University of Tulsa found that white-tailed prairie dogs (Cynomys leucurus) slaughter Wyoming ground squirrels (Urocitellus elegans) within their territory and leave their bodies to rot where they fall. They reported their findings in the journal Proceedings of the Royal Society B.
Prairie dogs are burrowing rodents that live in western North America. They belong to the squirrel family. The animal gets its name from the prairies (grassy plains) where it lives, and from its warning call, which sounds like the barking of a domestic dog. Prairie dogs have short legs; long, sharp claws; small eyes at the top of the head; and a short tail. Their thick fur is light brown. Adults measure from 9 to 15 inches (23 to 38 centimeters) in length, including the tail, and weigh from 1 to 3 pounds (0.5 to 1.4 kilograms). Prairie dogs live in burrows. They come out of their burrows only in the daytime to eat. Their diet consists mostly of plants, especially grasses. Occasionally, they eat grasshoppers and other insects. Prairie dogs are social animals that live in large groups called colonies or towns that may contain more than 500 residents.
While observing white-tailed prairie dogs, Hoogland and Brown noticed that they would occasionally seize intruding ground squirrels and tear at them and beat them against the ground. Being mostly herbivorous (plant-eating), the prairie dogs did not eat their kills, but rather abandoned them to be scavenged by birds and other animals. Some prairie dogs were “serial killers,” killing multiple ground squirrels over one or more years. The researchers determined that the offspring of killer ground squirrels lived longer on average. Ground squirrels and prairie dogs both eat grasses, so they suspect that the killings were motivated by competition for food: with fewer ground squirrels in its territory, a mother prairie dog would have more grass for itself and its pups to eat. This is the first known example of a herbivorous mammal killing another herbivorous mammal of a different species in competition for food.
Even if you aren’t impressed by the prairie dog’s killer tendencies, you should never touch a prairie dog, or even get very close to one, no matter how cuddly it looks. Like any wild animal, it will defend itself by scratching and biting. Prairie dogs, however, are carriers of plague. Plague is a serious infectious disease caused by the bacteria Yersinia pestis. Many millions of people were killed by outbreaks of plague during the Middle Ages in Europe and Asia. Many prairie dogs are not immune to plague, and populations have plummeted since the introduction of the disease by European settlers in the 1600’s.
In addition to suffering from plague, prairie dogs have also been slaughtered by cattle ranchers. Ranchers thought that their cattle could injure themselves if they stepped in a prairie dog hole, although this almost never happens. Ranchers also believed the rodents competed with cattle for grass. Actually, cattle seem to prefer to graze around prairie dog colonies. Scientists think the prairie dog’s burrowing activity releases more nutrients in the soil to the surrounding grasses, making it better for the cattle. Though they might be killers, prairie dogs are important animals in the American West.