A shadow races across a prairie dog town, stirring up a sudden panic of alarms and dashes to safety. A shriek stills the community. Overhead, the squeals of an unwary pup rapidly diminish as it is carried off in a clutch of gleaming talons of a golden eagle, above, to a nest of hungry eaglets, below.
Many pups and some adults are lost to predators. While small, prairie dogs are fair game for rattlesnakes and burrowing owls. Hawks, like the eagles, ambush pups from the sky. Patrolling coyotes are quick to sense the pups’ hesitation and to capitalize on the uncertainty. Badgers excavate with astounding speed; bobcats rush from concealment of any nearby cover. And in some places the most dreaded predator of all is the black-footed ferret, which enters the burrow itself to surprise and trap its prey. But eradication programs against the prairie dog have made the ferret nearly extinct; none has been seen at Devils Tower since the late 1800s. Some of the other predators of the prairie dog also have been nearly eliminated by man. And with the loss of natural predators, prairie dog populations flourish rapidly. Unless these predators are allowed to make a comeback, prairie dog control programs will be inevitable.
The black-footed ferret, a large weasel, makes its home in prairie dog towns, but it is extremely rare.
The coyote frequently prowls prairie dog towns in the early morning and evening.
The bullsnake hangs around burrows to prey on pups and other small rodents, killing them by constriction.
The prairie falcon nests on the Tower and occasionally feeds on residents of the prairie dog town.
The burrowing owl often nests in old burrows and sometimes preys on pups. Prairie dogs eat owl eggs and young.
The badger is short, broad, and a formidable digger. It concentrates its preying on new, one-entrance burrows.
Should the individual invited to mouth contact not reciprocate, an immediate challenge is made. Apparently, mouth contact is the only positive means of identification available to prairie dogs, and any animal refusing it is immediately deemed a trespasser and aggressively evicted. The wild chase that ensues, accompanied by indignant calling and fierce chattering of teeth, sometimes leads the righteous landowner deep inside its neighbor’s territory. The roles abruptly reverse and, after a moment of mutual realization, the pursuer suddenly becomes the pursued.
In the glare of the early evening sun it is difficult to distinguish the individual prairie dogs as they go about their various activities. A single warning call, however, and the town instantly sprouts battalions of erect postures. For a moment, each motionless, backlit figure shines its sun-haloed position. All the disparate activities of the scattered animals become instantaneously fused to a single purpose: identifying the danger.
Vocalizations distinguish the prairie dog from all other rodents. At least ten different calls have been identified in the blacktail class of prairie dogs. Most of the calls—such as the challenge bark, defense bark, disputing “churr,” fighting snarl, fear scream, muffled bark, and tooth chattering—do not involve the entire community. Except for the fear scream, which is immediately noted by all members, these vocal signals are largely ignored by neighboring animals since they usually denote a local disturbance among the prairie dogs themselves. There are three warning calls, however, that are intended for the entire community; these constitute the bond that unites all the separate coteries of the town into a single social unit.
At the sound of the warning bark, usually uttered by many animals at once and quickly relayed through the entire town, each prairie dog immediately rises to alert in an attempt to define the immediate danger. If the wave of alarms is particularly intense, the animals usually rush to burrow mounds, where they will await further developments. Usually only the prairie dogs in the immediate vicinity of an enemy will retire below ground. The remainder of the population continues to observe and sound the alarm. As an enemy approaches a particular burrow, the frequency and intensity of the occupant’s warning bark increases. Only at the last moment will the prairie dog cut short its tirade, capping it with an indignant churk as it dives below ground.
Another, more urgent, signal is the hawk warning call. The high-pitched, musical twin notes of this cry prompt an immediate dash for cover. Unlike the typical reaction to the warning bark, response to the hawk warning call is unhesitating. When this cry is given, seconds count, and visual confirmation of danger is not required to prompt a rush to safety.
After danger has passed, the all-clear is sounded. Known as the song bark, this melodic whistle is always associated with a particular body posture. Rising up on its haunches, the prairie dog points its nose to the sky, gives the whistle, and promptly falls back on all fours. When learning to execute this call, pups usually topple over backwards. Once uttered, the call is repeated sporadically throughout the town.
Communication is as important to the survival of the prairie dog society as is adequate food and shelter. Towns decimated by disease or poisoning soon vanish if the survivors are too few or scattered to communicate effectively. Deprived of an efficient warning system (and perhaps of the psychological need of social contact, as well), individual animals make easy targets for predators. Certainly they are too large and conspicuous to blend in well with their sparse surroundings. Unlike their small, well-camouflaged cousins, the thirteen-lined ground squirrels, prairie dogs cannot survive as individuals.
After the females leave their weaned pups to establish new burrows for themselves, the young will remain together for a while until they, too, begin to split up. No longer do they resemble the playful, romping pups of spring, annoying their elders with their ceaseless games, demands for attention, and disregard for territorial boundaries. Now full-fledged members of their clans, they capture grasshoppers in a business-like fashion. Like the season, they have matured. With the company of their elders they now share a suspicion of the sky and every uninspected plot of ground.