Posted Wednesday, March 23, 2005

Seasonal closure for taking prairie dogs starts April 1

Last year, the white-tailed prairie dog, Cynomys leucurus, was added to Utah's yearly seasonal closure list along with the Gunnison prairie dog, Cynomys gunnisoni. This year, the closed season for both species is from April 1 – June 15, 2005. During this time, no taking of prairie dogs is allowed on public lands.

Prairie dogs Photo by Ron Stewart

The seasonal closures for both species of prairie dogs are part of a protective action to try and keep the two species from moving toward listing under the Endangered Species Act. Both species have seen serious declines in their population numbers and available quality habitat. The seasonal closure helps protect the prairie dogs during the breeding season.

Two additional closures exist in Utah. The Utah prairie dog is listed as "Threatened" by the US Fish and Wildlife Service (FWS). It is protected year-round throughout all of its range in southwestern Utah. The Coyote Basin area in northeastern Utah also has a year-round closure to protect the white-tailed prairie dog in its role as the main prey base for the endangered black-footed ferret.

Life history

Lewis and Clark get credit for officially discovering and naming the prairie dog. The name is misleading because it isn't a dog; it is a member of the rodent family. It was named because of the 'barking" sound it makes. There are five species of prairie dog, three of which are found in Utah: the white-tailed in the northeast, the Gunnison in the southeast (east of the Colorado River) and the Utah prairie dog in the southwestern part of the state.

The three species found in Utah are colonial but have a looser social structure and occur at a lower density than their cousins the black-tailed prairie dogs found east of the Rocky Mountains. Utah's prairie dogs, which are smaller than the black-tailed species, are generally found in desert grasslands and shrub grasslands and can be found at both low altitudes and up to around 10,000 feet. Black-tailed prairie dogs prefer the lower elevation grasslands (without shrubs) found in the Great Plains.

Status of prairie dogs

The FWS was petitioned in 2002 to place the white-tailed species on the threatened and endangered species list. In 2004, they rejected the petition based on lack of information. The FWS concluded the petition did not contain substantial scientific data that the petitioned action might be warranted."

According to the FWS, "White-tailed prairie dogs are found across the western half of Wyoming, western Colorado, the eastern portion of Utah, and a small portion of southern Montana. The largest remaining complexes or groups, occupying more than 5,000 acres each, are primarily found in Wyoming. An estimated 55 percent of white-tailed prairie dog habitat is found on lands belonging to the U.S. Bureau of Land Management."

"The petition certainly raised valid issues," said Laura Romin, FWS biologist. "It is our hope that the state and federal agencies will continue to evaluate any known localized threats to the species, and take action to sufficiently reduce those threats to ensure species conservation for the long-term."

Recently, the FWS received another petition, one to list the Gunnison prairie dog but as yet no ruling has been issued.

Survival

Prairie dogs, as a species, face numerous threats to their survival; the main ones are poisoning, loss of habitat, drought, exotic diseases and possibly shooting or "plinking."

In the 1900s, poisoning campaigns on both private and public lands seriously reduced their numbers and wiped out total colonies in many areas. This practice has largely been discontinued but still occurs in some areas.

One of the reasons for poisoning was to reduce their numbers on agricultural fields. Prairie dogs do eat many of the crops growers produce as well as create a complex of tunnels to drain water away from the crops. Their burrows can also create mounds, which hinder the use of planting and harvesting equipment.

Another reason given for poisoning prairie dogs on rangelands was that prairie dogs competed with cattle and other livestock for forage.

Early studies concentrated on the plants prairie dogs eat. They did show a competition for forage with livestock as prairie dogs eat a wide variety of forbs (flowering plants like dandelions) and grasses. Later studies looked beyond the forage species consumed to the effects of co-habitation. These studies show cattle raised on ranges with prairie dogs usually have better growth rates than those raised where prairie dogs have been eliminated. The reason is the prairie dogs help keep a few aggressive plants from dominating the range, thus less aggressive forbs and grasses are able to grow. This extra diversity of plants contains more nutrients than that of a monoculture so the cattle and other livestock get a higher quality feed.

Habitat loss continues to be a major problem. Every year more land comes under development, exotic plant species invade and change the ecology of the shrub-grassland complexes, and drought, fire prevention, and numerous other factors take their toll on the quality and quantity of habitat.

In eastern Utah, drought has been a major factor over the last five or six years. Generally, prairie dogs are fairly tolerant of drought conditions since they live and evolved in a semi-desert environment. The last few years however have set new records on lack of moisture. Drought tolerant plants have been severely affected, often to the point of dying out. This lack of plant production is reflected in the reproduction and survival rates of the prairie dog population. The populations in numerous prairie dog colonies are at the lowest numbers biologists have seen.

The drought has also accelerated perhaps the greatest problem facing western ranges, invasion by cheatgrass. In the last few years, this invasive plant from Asia has become a major factor in the loss of rangelands across the west. Cheatgrass is a very aggressive invader and it responds quickly to fire. It is one of the first plants to start growing in the spring so it takes up valuable water and nutrients. By mid to late spring, it forms seed heads and then dries out so it burns easily. Having dry cheatgrass in the understory allows a fire to spread easier and burn hotter killing more shrubs and other plants, which opens up new areas for cheatgrass to invade and dominate.

Another concern is the introduction of exotic diseases, especially plague and canine distemper. Prairie dogs have almost no immunity to diseases from other continents like Europe, Asia and Africa so the introduction of one of these diseases into a colony can literally wipe it out. Scientists are looking for solutions but this takes time and the diseases may not cooperate.

Plinking (shooting) may also be a problem. This loosely defined sport seems to be growing in popularity with some plinkers shooting hundreds of rounds during a weekend. What effect does all of this shooting have on a prairie dog colony? One camp claims none; populations will remain stable. The other camp claims a potential for major population declines, especially in smaller colonies, and the potential loss of habitat due to this decline in numbers.

The complication or difference in these studies might be found in how the colony works, the colony size and the species of prairie dog.

Unlike many of the more familiar rodents like rats and mice, which can have multiple births multiple times per year, prairie dogs give birth to three or four young, once, in the spring. This is a relatively slow reproductive rate for an animal largely considered as the grassland's main prey base.

Most studies on colonial animals have found certain areas, generally in the middle of the colony, are more preferred than others. If an animal dies or is removed from the preferred area, an animal from the fringe will move in to take its place. This may be what the first camp is seeing.

These studies also show if enough animals are removed, the fringe is abandoned as more and more animals move to the preferred area in the middle. This is what the second camp believes may be happening, excessive plinking may be removing those animals in the preferred area faster than their slow reproductive rate can replace them, especially in the smaller colonies. When the fringe areas are abandoned, the vegetation isn't trimmed back so it gets taken over by taller shrubs and undesired plants thus making it unusable habitat for prairie dogs.

All sides agree prairie dog colonies have been reduced. "Since the turn of this century, prairie dog populations have declined as much as 98% throughout North America" (Brian Miller 1994).

While the studies and discussion continues, the DWR and Wildlife Board are concerned enough to create the seasonal closures in an attempt to protect Utah's three species of prairie dogs until their young are old enough to fend for themselves. Hopefully, this will reduce the losses enough for the colonies to remain stable.