York (extirpated), northern New Jersey, and northern Pennsylvania southwestward through western Maryland, Tennessee, Kentucky, West Virginia, northern and western Virginia to northeastern Alabama and northwestern North Carolina with isolated populations north of the Ohio River in southern Ohio (extirpated) and southern Indiana (reintroduced). The Tennessee River is generally accepted as the southern range limit. There are no recognised subspecies. Fossils belonging to the species are known from mid Pleistocene deposits in Maryland and West Virginia. Although the Allegheny woodrat is not a federally listed threatened or endangered species, it is in major decline and is state listed: Causes and management of decline In the northern parts of their range (New York, New Jersey and Pennsylvania), the Allegheny woodrat population has been in declined over the past 30 years. They have been extirpated from Connecticut and New York, as well as parts of Pennsylvania, New Jersey and Maryland. The reasons for the decline are not yet entirely understood, but are believed to involve a combination of factors. The first is a parasite, the raccoon roundworm, Baylisascaris procyonis, which is almost always fatal to woodrats. Raccoons easily adapt to environmental change and have thrived in traditional woodrat habitat, causing infection of woodrats when they eat plant and seed material in raccoon feces that contain the parasite. Other frequently cited causes of decline include the near total loss of American chestnuts caused by chestnut blight and the defoliation of oak trees by an invasion of spongy moths (lowering available supplies of acorns for woodrats). Increased competition for acorns with overabundant white-tailed deer and growing populations of black bears and turkeys may also have a negative impact on woodrat survival. Predation by great horned owls has also been cited. Finally, increased human encroachment causes fragmentation and destruction of the woodrats' habitat. Though present for at least 20,000 years in New York State, the Allegheny woodrat was extirpated from New York by 1987, perhaps due to an increase in the state's raccoon population from the 1960s onward. A reintroduction of 30 woodrats from West Virginia near Mohonk was a complete failure; the population was wiped out within a year, and of 52 animals, only 12 had inspectionable carcasses; 11 of the 12 had died from roundworm complications. Indiana's Nongame and Endangered Wildlife Program currently monitors woodrat population status and distribution. They are also conducting field searches for new localities and research to identify the factors