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Zempoaltepec Vole

Microtus umbrosus
EN · Endangered Rodentia Cricetidae
Size
9-11 cm + tail 3-4 cm
Weight
25-40 g
Activity
Variable (day and night)
Sociability
Solitary

Description

It shares the Zempoaltépec mountain massif with at least one other endemic rodent of equally restricted range, a clear example of how a single isolated mountain in Oaxaca can become a refuge for exclusive life. The Zempoaltepec Vole is a discreet vole that lives hidden in high-altitude meadows and open coniferous forest on the highest peaks of this range, moving through a network of surface runways and shallow burrows beneath dense vegetation. Like other voles, it feeds almost exclusively on plant material and helps to aerate the soil through its constant digging. Its name refers to the Zempoaltépec massif itself, outside of which no other population is known anywhere in the world.

How to identify it

A small, compact rodent with a cylindrical body, a short tail, small ears barely visible in the fur, and dark brown pelage. It is distinguished from other voles in the Oaxaca region by its exclusive restriction to the Zempoaltépec massif, and by cranial details that require direct examination for reliable separation from sibling species.

Signs and tracks

Tiny track, barely 1-1.5 cm long, with 4 foretoes and 5 hind toes, rarely visible except in fine mud along its surface runways. Small, cylindrical droppings 4-6 mm long are left in small piles along the surface runways it cuts beneath dense vegetation. These surface runways, 3-4 cm wide and visible as flattened tunnels through the grass when pushed aside, are the most reliable sign of its presence.

Habitat and range

High-altitude mountain meadow and open coniferous forest, generally above 2800 m elevation. Endemic to the Zempoaltépec massif in the Sierra Mixe of Oaxaca, southern Mexico, with no known presence on any other mountain.

Diet

Herbivorous, feeding on grasses, tender stems and roots in the high-altitude mountain meadows where it lives.

Behaviour

It digs a network of shallow burrows and surface runways beneath dense vegetation, exhibiting territorial behaviour and short bursts of activity distributed throughout the day and night.

Conservation

Its restriction to a single mountain, together with the degradation of high-altitude meadow and coniferous forest habitat, leaves its populations in continuous decline with very little room for recovery.

Threats

Degradation of high-altitude mountain meadow through overgrazing by livestock, alongside the extreme geographic restriction of the species to a single mountain, which leaves it vulnerable to any adverse local event.

Other accounts in Cricetidae

See all species accounts for rodents · Full species index

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