Discovered in 2004 in southern Arizona, Cockrum's Gray Shrew was the first new mammal species described in that state in almost thirty years. Its discovery showed that Crawford's Shrew, previously thought to be a single species widespread across southwestern North America, actually comprised several distinct lineages. It is a tiny animal, weighing just a few grams, living hidden in the desert scrub of Arizona and northern Sonora, and goes almost unnoticed even where it is common.
Cockrum's Gray Shrew is tiny, with grey-brown fur and very small ears, almost hidden in the fur, like other shrews in the genus. It is practically indistinguishable in the field from the Crawford's Shrew (N. crawfordi) and other Notiosorex species with which it shares its range. Only genetic or cranial analysis allows them to be reliably separated.
Its minimal weight means it rarely leaves recognisable tracks except on very fine substrates such as ash or loose dust. Droppings are the most accessible sign of its presence. They are cylindrical, barely 3-4 mm long, and contain visible arthropod fragments. However, they are almost identical to those of other desert shrews in the area. Cockrum's Gray Shrew shelters in abandoned Neotoma mounds or under agave clumps and dense shrubs. This behavioural detail is more useful for locating Cockrum's Gray Shrew than any physical tracks and signs.
Desert scrubland of southern Arizona (USA) and central Sonora (Mexico).
Insects and other small arthropods, hunted among the leaf litter and the base of shrubs.
Solitary and nocturnal, it does not dig its own burrows. Instead, it uses shelters already built by other animals, such as Neotoma mounds or the base of dry agaves.
It is considered stable within its relatively small range in Arizona and Sonora, with no documented signs of decline.
Loss of desert scrub due to urban expansion in southern Arizona and land-use changes in Sonora.
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