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LONG-TAILED WEASEL
Mustela frenata Lichtenstein 1831

Order Carnivora : Family Mustelidae

DESCRIPTION. A slender, long-bodied carnivore with small head, long neck, short legs, and relatively long, slender tail; upperparts yellowish brown; head blackish; spot between eyes, broad band (confluent with color of underparts) on each side of head between ear and eye, chin and upper lip white; tip of tail black, remainder colored like back; underparts, except for chin, orange buff—color extends down back of front legs over forefeet and on inside of hind legs to foot and sometimes onto toes. Dental formula: I 3/3, C 1/1, Pm 3/3, M 1/2 × 2 = 34. Averages for external measurements: of males, total length, 488 mm; tail, 192 mm; hind foot, 51 mm; of females, 438-187-42 mm. Weight of adult males, about 300–500 g; females slightly less.

Mustela frenata

DISTRIBUTION. Although few scientific records exist, long-tailed weasels are widely distributed in Texas except for the Panhandle region. They occupy a variety of habitats, including brushlands, fencerows, upland woods and bottomland hardwoods, forest edges, and rocky, desert situations. They usually live close to water and occasionally under a house or barn in proximity to humans. It has been suggested that the absence of water may be a factor limiting distribution of long-tailed weasels.

Distribution of Mustela frenata

SUBSPECIES. Mustela f. neomexicana mostly west of the 100th meridian, M. f. texensis in the central part of the state, M. f. primulina in the extreme northeastern part of the state, M. f. arthuri east of the Balcones Fault Zone in east-central and southeastern areas, and M. f. frenata in the southern part of the state along the Gulf Coast and adjacent to Mexico.

HABITS. Long-tailed weasels typically nest in a rotten log, hollow stump, under tree roots, or in a hole in the ground. Their den contains grass and leaves and is lined with rodent and rabbit fur. Depending on the condition of their habitat, they may have one or several homes. Weasels are active both in the daytime and at night but more so after dark. They are active year-round and show no tendency to hibernate during winter. They range over a fairly large hunting area, which may take them several days to traverse. Their nightly forays usually cover only a portion of their home range. When running, weasels arch their back up in a fashion reminiscent of an inch worm.

Although weasels occur in most ecoregions of the state, their secretive nature makes it difficult to define their distribution or abundance accurately. Few scientific records are available and consequently little is known about some of their natural history attributes.

The bulk of their diet is composed of small mammals, including moles, shrews, ground squirrels, tree squirrels, flying squirrels, pocket gophers, woodrats, cotton rats, deermice, harvest mice, and small cottontails. Occasionally, they will eat small birds, reptiles, amphibians, and insects. Most of their prey is killed by a bite on the back of the neck, with the body and legs of the weasel hugging the back of the victim. Weasels often kill more than they need, in which case the surplus is stored for future use.

Long-tailed weasels are polygamous and breed mainly in July or August. Implantation may be delayed for several months, resulting in a gestation period of 205–337 days (average 279 days). Embryos generally implant in early spring and develop to full term in <27 days. The single litter, which may number up to nine young (average four to five), is produced in April or May.

Newborns are blind, nearly helpless, and covered with fine white hair. The eyes open at 36 days, at which time they are already weaned and feeding on solid food. There is some indication that the male may aid in rearing the young. The young remain with the female until they are fully grown. The scent glands begin to function at 6 weeks of age. Sexual maturity and adult size is reached in females at about 3 months (they usually mate in the summer of their first year), but not in males until 12 months.

Known predators include rattlesnakes, cottonmouths, foxes, bobcats, house cats, and dogs. The scent of this species is almost as powerful as that of a skunk and no doubt serves the animal as an excellent defensive weapon.

Although they are listed as a fur-bearing animal by Texas law, long-tailed weasels are of little economic importance because of their small body size and limited market demand.

POPULATION STATUS. Uncommon. Given the sporadic distribution and lack of trapping data, it is difficult to ascertain the population status of this species. Long-tailed weasels are seldom seen, and it is even rarer to encounter one.

CONSERVATION STATUS. The IUCN lists the long-tailed weasel as a species of least concern, and it does not appear on the federal or state lists of concerned species. There is concern about the long-term status of weasels in Texas because of the loss of natural surface water, which is a preferred part of their habitat. This species should be carefully monitored in the future.

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From The Mammals of Texas, Seventh Edition by David J. Schmidly and Robert D. Bradley, copyright © 1994, 2004, 2016.  Courtesy of the University of Texas Press.

Natural Science Research Laboratory