Before delving into a discussion on methods of controlling the numbers of prairie dogs, it is important to emphasize the fact that the mere presence of prairie dogs does not necessarily signify the need for control. If, after careful evaluation of a situation, it becomes evident that some measure of control is necessary, one must decide what population of prairie dogs could be considered to be acceptable. Are there techniques that could be used to make cohabitation or shared use of the land feasible?
If prairie dogs appear to be out of control and destroying rangeland used by grazing cattle, is there a way to determine the economical impact of the prairie dogs on rangeland quality? Does the economic loss significantly exceed the cost of appropriate eradication of the prairie dogs? From a purely economic standpoint if the economic loss caused by prairie dogs does not exceed the cost of their removal it does not make sense (or cents) to remove them.
If the prairie dog invasion occurs in a park, is there a way that the prairie dog colony could be included in the comprehensive plan for park development, by controlling the size of the population, developing a prairie dog awareness program, relocating them to another area within the park, etc.? It is possible that your research will reveal that it would cost more to eliminate and maintain a prairie dog free environment than it would cost to alter plans and agree to coexistence with the critters.
Assuming you have analyzed the situation and determined that the prairie dogs must be removed, it then becomes necessary to determine what method of control is appropriate. In order to determine what method should be employed, there are several factors that must be considered:
Once you have determined what your individual situation is, it is time to review possible options.
Total exclusion is not often practical or economically feasible except for small areas. However, some success has been reported by burying small mesh wire fencing about two feet deep and leaving 3 feet above ground. A slightly outward sloping top to the fence will provide additional protection (1, 2). Prairie dogs prefer short grass so that they can see intruders. They normally clip it close to the ground. Fences that obscure vision (like snow fences, or burlap fences), hay bales, etc. have been used to block prairie dogs' view and make a habitat less suitable to prairie dogs. Windrows of pine trees have also helped. Unfortunately exclusion devices have proven to be only mildly effective in most situations (1,2), and this method of control is often prohibitively expensive. The experimental use of plastic visual barriers proved to be ineffective in reducing re-colonization rates because they were destroyed by wind within 3 weeks of installation (4). Switchgrass has been used to control the expansion of prairie dog colonies. Plant these grasses in close rows that will produce a dense, self-maintaining barrier (6).
In general, most frightening techniques have not worked (1). Boulder, Colorado has tried enclosing a prairie dog infested area of a park and turning it into a dog park (7). It is assumed that the prairie dogs will leave rather than compete with dogs (at last report, the jury was still out on this one).
A big factor in prairie dog control is range management. Overgrazed rangeland means short grass, exactly what prairie dogs are looking for. Prairie dog density must be considered when determining stocking rates for cattle. Assuming that a prairie dog eats about 8 pounds of forage/month, and the density of prairie dogs is determined to be 25 per acre and the dietary overlap of cattle and prairie dogs 75%. Six acres of prairie dogs would require 1 cow/calf unit (Animal Unit Month (AUM)) or 900 pounds of grass per month (1,2).
If the prairie dog population is too large for the rangeland to support both the cattle and the prairie dogs, the rancher will have to choose between reducing the number of cattle to be grazed on the land and reducing the number of prairie dogs. If the latter wins out, prairie dog control measures will likely be employed. We will deal with the option of range management and the effect of prairie dogs on rangeland quality and distribution in a separate article.
Federal regulations require that live trapping of prairie dogs be accomplished using only humane traps that do not injure the prairie dog upon capture. The traps must be checked regularly to insure that the animal does not go without food, water or shelter for an unnecessary period of time. 9 CFR, Section 2.126, requires that an itinerary of capture dates and sites be provided to the appropriate Animal Care Regional Office a minimum of two days prior to collection (9). In addition, state and local governments may have additional permitting requirements for either capture or relocation. Once a prairie dog has been caught, there is the question of what to do with it. Relocation is the desired fate of trapped prairie dogs, but it is often hard to find an acceptable place where the prairie dog is welcome. As a result, trapped prairie dogs are often humanely euthanized.
The cost of capturing and moving prairie dogs can run anywhere from $30 - $300 per prairie dog (6). The process can involve trapping, flushing the critters out with soapy water or vacuuming them out with a vacuum truck. Quality of handling varies almost as much as the price. Some companies claim to relocate the prairie dogs, while, in fact the animals are being euthanized (6). Mortality rates also vary greatly. Little verifiable data is available concerning the mortality rate when soapy water is used to flush out and capture prairie dogs (5). Vacuuming of prairie dog colonies results in about 5% mortality due to fatal injuries or injuries severe enough to require euthanasia (5). Trapping of prairie dogs results in loss of less than 1% of the prairie dogs (5). Prairie dogs can be removed any time except between February and May when pups are likely to be too young to be moved (6).
While live trapping results in fewest initial losses of individuals, it is extremely time consuming and expensive (6). The greatest losses of life are actually the result relocation rather than capture. City and county officials have reported a 30-50% survival rate of relocated prairie dogs within a few months of release, while private organizations report survival rates of 50-95% (6).
There are various types of relocation sites. Some are strictly relocation for the sake of saving the prairie dog. Others involve more integrated programs such as the Black Footed Ferret Recovery Program. Some people are opposed to sending prairie dogs to the Black Footed Ferret Recovery Program. It seems too much like sending them to the firing squads.
One must remember, however, that the black Footed Ferret is one of the most specialized mammal species in the world. Black Footed Ferrets feed solely on prairie dogs. They live and raise their young in prairie dog burrows (11). Without the prairie dog there can be no Black Footed Ferret. Presently the Black Footed Ferret is threatened with possible extinction. Efforts have been under way for 20 years to save the Black Footed Ferret. At one breeding center in Colorado Black Footed Ferrets are raised in captivity, taught how to hunt for prairie dogs, and then released into the real world (a protected prairie dog colony). While this might seem like a sad fate for relocated prairie dogs, one must remember that in nature survival of the species, not individuals, is most important. At one point in history the prairie dog and Black Footed Ferret lived in harmony at the community level (if not the individual level). The ferret culled the weaker prairie dogs. That kept the colony strong and prevented overpopulation. The prairie dogs provided food and shelter for the ferrets. Maybe someday as a result of these breeding programs, prairie dogs and Black Footed Ferrets will live in harmony again.
Unfortunately, there are times when none of the methods of prairie dog control listed above are applicable. In those cases, extermination of the prairie dog may seem to be the only solution. These techniques, including poisoning, fumigating and a relatively new technique, underground shockwaves, will be discussed in the next article in this series.
Other articles in this series:
If you need to cite this page, you can copy this text:
Roberta Barbalace. Prairie Dog Control Part I. EnvironmentalChemistry.com. Apr. 3, 2007. Accessed on-line: 1/24/2017