Mustela erminea—Ermine // Mustela frenata—Long-tailed Weasel // Mustela nigripes—Black-footed Ferret
Weasels are widespread in our region, ranging from valley habitats in desert to grasslands to montane coniferous forests. Their long bodies and short legs make them fit to go into burrows after their prey. To a degree, the prey universe is divided up by size. Large weasels, such as the Black-footed Ferret, have the size and bulk that allows them to enter large burrows, such as those of prairie dogs, and take on prey that potentially could do bodily harm to smaller weasels. The Long-tailed Weasel is sized for most ground squirrel burrows, and the ermine for mouse-size habitations.
Fig. 1. Black-footed Ferret. Image courtesy of U.S. National Park Service.
Conkling (1932) listed "weasel" without further comment, as did Lindsay and Tessman (1974).
Late Blancan: 111 Ranch (Morgan and White 2005).
Mid/Late Wisconsin: Rampart Cave (Lindsay and Tessman 1974).
Late Wisconsin: Camel Room (UTEP).
Late Wisconsin/Holocene: Conkling Cavern (Conkling 1932).
Conkling 1932; Lindsay and Tessman 1974; Morgan and White 20005.
Ermine are basically northern creatures that today come south in the Rocky Mountains into northern New Mexico. The southernmost record is from the Sandia Mountains (Ivey 1957), a sight record that should be verified. The Balcony Room record is suggested to date to about 12,000 BP (Harris 1993b) and comes from Test Trench 1, Grid 7, Level 3 of that site. The date is interpolated from other sites within Dry Cave that are believed to bracket the Balcony Room record.
The tentative record from Pendejo Cave is based on an innominate that is smaller than our comparative material of the other species of Mustela in the region, M. frenata. The record from Balcony Room is based on a dentary (Fig. 3).
Fig. 1. Mustela erminea. Photograph by Steve Hillebrand, courtesy of the U.S. Fish & Wildlife Service.
Fig. 2. Modern specimens of Mustela erminea showing typical weasel morphology and the great amount of sexual dimorphism displayed by mustelids. Male on left, female on right (occipital region of female damaged). Scale in mm.
Fig. 3. Left dentaries of Mustela erminea (top) and Mustela frenata. The latter probably is from a female. M. erminea specimen (UTEP 12-240) from Balcony Room of Dry Cave; M. frenata specimen (120-191) from Big Manhole Cave. Note that the scale is twice that of Fig. 2.
Medial Irvingtonian: SAM Cave (Rogers et al. 2000).
Late Wisconsin: Balcony Room (Harris 1993b); Pendejo Cave (Harris 2003: cf).
Harris 1993b, 2003; Ivey 1957; Rogers et al. 2000.
Long-tailed Weasels are the most common of the weasels in our region, both today and during the Pleistocene, to judge from the number of records and specimens.
Today, Mustela frenata is fairly common in our region, from the bottomlands of the Rio Grande into montane forests in New Mexico. In Arizona, distribution is primarily along the eastern border and along the Mogollon Rim. Although these weasels certainly will take any prey they come upon that's small enough to handle (which includes animals bigger than themselves), likely ground squirrels form the bulk of their diet.
Fig. 1. Long-tailed Weasel. The coloration is a bit different from natives of our region, but the morphological characteristics are the same. Photograph courtesy of U.S. Forest Service.
A number of other mustelids and mephitids, mostly with excellent preservation, were closely associated in a small area of Big Manhole Cave, but whether an outstanding denning site over a number of years or a different explanation remains a mystery.
Fig. 2. A fossil skull of Mustela frenata from Big Manhole Cave. This individual undoubtedly was female and somewhat smaller than the modern individual shown in Fig. 3 (figures 2 and 3 are to the same scale).
Fig. 3. Ventral views of the modern skulls of male (left) and female Mustela frenata. The thin bones on the underside of the male are elements of the hyoid apparatus. Scale in mm.
Rancholabrean: Papago Springs Cave (Czaplewski and Mead et al. 1999: cf.).
Mid/Late Wisconsin: Big Manhole Cave (Harris 1993c); Dark Canyon Cave (Tebedge 1988).
Mid/Late Wisconsin/Holocene: Sierra Diablo Cave (UTEP).
Late Wisconsin: Animal Fair 18-20 ka (Harris 1989); Camel Room (Harris 1993c); Harris' Pocket (Harris 1970a); Human Corridor (Harris 1993c); Lower Sloth Cave (Logan 1983); Muskox Cave (Logan 1981); Pendejo Cave (Harris 2003); Sheep Camp Shelter (Harris 1993c); TT II (Harris 1993c); U-Bar Cave 14-15 ka (Harris 1989); U-Bar Cave 15-18 ka (Harris 1989); Upper Sloth Cave (Logan and Black 1979).
Late Wisconsin/Holocene: Pendejo Cave (Harris 2003).
Czaplewski and Mead et al. 1999; Harris 1970a, 1989, 1993c, 2003; Logan 1981, 1983; Logan and Black 1979; Tebedge 1988.
Black-footed Ferrets are now an endangered species, largely because of control measures taken against their major prey, prairie dogs. The species is a relatively large mustelid, consistent with being able to enter prairie dog burrows and take on the relatively large rodents.
Fig. 1. A Black-footed Ferret at the mouth of a prairie dog burrow. Photograph courtesy of the U.S. National Park Service.
Fig. 2. Ventral and dorsal views of a fossil Mustela nigripes skull from Big Manhole Cave, Eddy Co., NM. Scale in mm.
Fig. 3. Left dentary of Mustela nigripes from Isleta Cave No. 2. Scale in mm.
Mid/Late Wisconsin: Big Manhole Cave (Harris 1993c).
Late Wisconsin/Holocene: Burnet Cave (Schultz and Howard 1935); Isleta Cave No. 1 (Harris 1993c); Isleta Cave No. 2 (Harris 1993c).
Harris 1993c; Schultz and Howard 1935.
Last Update: 12 Mar 2013