The Desert Gray Shrew is one of the smallest mammals in the North American desert and one of the smallest homeotherms on the planet. An animal as light as a coin, it needs to eat frequently to avoid starvation, because its metabolism drives its heart rate to nearly a thousand beats per minute at rest.
It lives hidden among the leaf litter and scrub of the southwestern United States and northern Mexico. Its life is as short and accelerated as its heart rate: it rarely survives more than a year in the wild.
Tiny, with grey-brown fur and a somewhat lighter belly. It has a pointed snout and small ears, which are somewhat more visible than in other shrews. The Desert Gray Shrew is easily confused with other Notiosorex species in its range (N. cockrumi, N. tataticuli, N. carrawayae). It can only be reliably distinguished from these by cranial or genetic characteristics, never by external appearance.
Its minimal weight (3-5 g) means the Desert Gray Shrew almost never leaves visible tracks, except in very fine dust or ash, where a tiny track less than 1 cm long may appear. Droppings, cylindrical, 3-4 mm long and containing arthropod fragments, are deposited near its refuges. It does not dig its own burrows: it occupies abandoned mounds of Ne
Shrubland and desert of the southwestern United States and northern Mexico, among leaf litter, dense shrubs, and the refuges of other animals.
Insects and other arthropods, occasionally supplemented with small vertebrates such as lizards. It can eat the equivalent of a good portion of its own body weight in a day.
Solitary and nocturnal, it avoids diurnal heat by remaining in other shelters. It breeds between late spring and autumn, with litters of 3 to 5 young after a short gestation of about three weeks.
It is considered stable and widely distributed throughout southwestern North America, with no signs of significant decline.
Loss of desert scrub due to urban and agricultural expansion in some areas of its range in the United States and Mexico.
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