All About Animals

The threats fall into four main categories. 1) Exotic disease, particularly sylvatic plague to which prairie dogs are highly susceptible. 2) Loss of habitat to agriculture and urbanization. 3) Habitat fragmentation and its many effects. 4) Control activities by government, private organizations, and individuals via poisoning and shooting. 

EXOTIC SPECIES/DISEASE: Sylvatic plague was introduced to North America around 1899 and first reported in black-tailed prairie dogs from Texas in the mid-1940s. It is a serious threat given its pervasiveness and efficacy, as it can kill more than 99% of prairie dogs in a colony and numbers do not appear to fully recover. Though prairie dogs have persisted in the presence of plague since about 1900 and prairie dog numbers are high given habitat loss and control efforts, the plague is still of concern to local populations and for long-term persistence. The plague is not well documented in black-tailed prairie dogs across their range though there is no reason to believe that plague is not as significant in black-tailed as it is in white-tailed prairie dogs. On large areas originally selected as possible ferret reintroduction sites, declines of up to 90 per cent from about 1985-2000 are generally attributed to sylvatic plague. Only about 10 percent of the historical range is both plague-free and available (not cropland). Widespread outbreaks in 2001 may indicate the beginning of an upcycle in plague occurrence. The significance of the plague in range-wide prairie dog mortality is unclear, though experts agree that where plague occurs it is extremely important in population dynamics. Plague may be introduced into a colony by other species or by dispersing prairie dogs, which bring plague-ridden fleas into a colony.
 

HABITAT LOSS AND DEGRADATION: Habitat loss has been an important factor in prairie dog declines in the past. It was estimated that about 36% of the land area in regions used by prairie dogs was covered by water developments, urban expansion, cropland, and improved pasture. It was detected that extensive colony loss on river terraces was a result of farming activities. Conversion of native prairie to farmland does not necessarily represent habitat loss to prairie dogs, but farmers will not tolerate prairie dogs in their fields. Similarly, prairie dogs prosper in empty urban lots and fields, yet this is not often tolerated given the plague risk. However, in New Mexico, urban (Gunnison's) prairie dogs are often allowed to remain because colony fleas are killed instead. Still, developments that destroy patches of grassland (e.g., roads, buildings, water impoundments) result in loss of potential prairie dog habitat and restriction of area for colony expansion.  
 

CONTROL: Control by humans, interacting with low forage production, is probably the main cause of loss of the prairie dog from the more arid parts of its range, including southwest New Mexico and southeast Arizona and Texas. For most of the 20th century, Animal Damage Control, its forerunners, and other control agencies worked hard to eliminate prairie dogs over wide areas. Towns were poisoned primarily with strychnine and zinc-phosphide baits (e.g., oats mixed with rodenticide). Poisoning was immediately followed up with extermination of any remaining living prairie dogs. Today prairie dog poisoning efforts are limited to local, problem populations and entail control, not extermination. Public control agencies, including ADC, do very little prairie dog control work, as most control is practised by land managers. These agencies do provide technical information and assistance, however. Distribution, abundance, and trend data indicate that inadequate regulatory mechanisms are not limiting black-tailed prairie dog populations at present, nor are they likely to within the foreseeable future.