Desert shrew

Notiosorex crawfordi

TAXONOMY

Notiosorex crawfordi (Coues, 1877), Texas, United States. Specimens from Tamaulipas, Mexico, were shown to represent a separate species described as Notiosorex villai. Another Mexican subspecies, N. c. evotis, was also elevated to specific status.

OTHER COMMON NAMES

French: Musaraigne du désert; German: Graue Wustenspitz-maus.

PHYSICAL CHARACTERISTICS

Head and body length 1.9-2.6 in (4.8-6.5 cm); tail 0.9-1.2 in (2.2-3.1 cm); weight 0.1-0.2 oz (3-5 g). Dark gray fur, lighter underneath. Long tail, visible ears. Reddish nose, hairless feet.

DISTRIBUTION

North and Central America from the southwestern United States east to central Texas and western Arkansas, Baja California, and northern and central Mexico.

HABITAT

An arid-adapted shrew occurring in a variety of xeric habitats. The most common occupied community is a semi-desert scrub association, with such vegetation as mesquite, agave, and scrub oak. Food and water resources are scarce, and amplitudes of daily temperatures are high in these habitats. Nests are usually constructed on the surface of the ground. The species has also been found in beehives.

BEHAVIOR

This species seems to be more social than other shrews. Captives are able to live together with little antagonism, and they live in high densities on small areas in the wild. It is active at night, twitching its snout and vibrissae while foraging. The known vocalization is a high-pitched squeak, emitted during occasional bouts of fighting or disturbance.

FEEDING ECOLOGY AND DIET

The diet consists of a variety of insects and other invertebrates, and dead vertebrates. It has a greater ability to cool itself by evaporation than do other shrews and the energy metabolism is lower than in other shrew genera. The desert shrew is able to enter shallow torpor that is believed to be an adaptation for coping with heat, aridity, and a fluctuating food supply.

REPRODUCTIVE BIOLOGY

Probably promiscuous. Pregnant females have been taken from April to November. Known litter size is 3-5. Its moderate basal rate of metabolism is apparently associated with a moderate litter size.

CONSERVATION STATUS

The loss of native coastal scrub flora and the increasing presence of the Argentine ant colonies may significantly effect the distribution and abundance of the species.

SIGNIFICANCE TO HUMANS None known. ♦

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