RECENT RANGE EXPANSION AND DISTRIBUTIONAL LIMITS OF THE 9-BANDED ARMADILLO (DASYPUS-NOVEMCINCTUS) IN THE UNITED-STATES

Prior to the mid 1850s armadillo dispersal may have been inhibited by native subsistence hunters, the Rio Grande acting as a physical hindra nce, and natural habitat barriers posed by fire-maintained grasslands. European colonists settled south Texas in mass during the latter half of the 19th century and largely removed existing impediments to armad illo range expansion, effectively releasing the species into the Unite d States. The speed of the armadillo's natural range expansion after 1 850 was probably accelerated by human travel and commerce into and out of its historic range in south Texas on a proliferation of roadways a nd railroads. This translocation process will likely continue and, com bined with natural dispersal, will provide the armadillo the opportuni ty to ultimately become established in any habitats in the United Stat es in which it can survive. Limits to future distribution will likely be determined by climatic factors, and may be bounded by regions recei ving at least 38 cm annual precipitation and having mean January tempe ratures >-2 degrees C, or fewer than 24 total annual freeze days. Arma dillos may have already approached a precipitation-define boundary to the west and distribution on the Great Plains limited by winter temper ature minima. They may be expected to continue their advance up the Ea st Coast to about the region of 41 degrees North Latitude, decreasing to 39 degrees North Latitude across the midwestern states. Future intr oductions on the West Coast may result in the establishment of armadil lo populations in suitable habitats from California to Washington, an event that has already taken place with another tropical mammal emigra nt, the opossum.