Spiny Pocket Mouse

Spiny Pocket Mouse, Chaetodipus spinatus

Spiny Pocket Mouse, Chaetodipus spinatus. A mom with four suckling babies found in fishing tackle in a storage shed in the greater Buenas Aires area of Los Barilles, Baja California Sur, December 2019. Total length 16 cm (6.3 inches). Body length 7.0 cm (2.8 inches). Note that the babies are differently colored than their mom. “Catch” courtesy of Mike Rousseau, Maple Ridge, British Columbia, Canada. Photograph courtesy of Brad Murakami, Surrey, British Columbia, Canada.

The Spiny Pocket Mouse, Chaetodipus spinatus, is a member of the Heteromyidae family of Pocket Mice. The Heteromyidae family consists of sixty-five species placed into three subfamilies and six genera. There are eighteen species in the Chaetodipus genus. The Spiny Pocket Mouse is known in Mexico as Ráton de Abazones de Baja California.

Spiny Pocket Mice have a pelage of stiff, long hairs with prominent flexible spines on their back, for which they are named. They vary in color depending upon their location, but are generally a drab brown dorsally transitioning to tan on their sides. Their long spines have black tips. They have small round ears and a tail that is slightly longer than their body. Their hind feet are elongated, measuring approximately 27% of the length of their head and body. They measure between 16.4 cm (6.5 inches) to 22.5 cm (8.9 inches) in length, and weigh between 13 g (0.46 oz) and 18 g (0.63 oz).

Spiny Pocket Mice are nocturnal, taking shelter from the daily heat in burrows. Their diet consists of seeds, desert shrubs, and grasses. The majority of their water intake is obtained from the food they eat. The Spiny Pocket Mouse is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, habitat use, and reproduction. 

The Spiny Pocket Mouse occurs in southern Nevada and southeast California in the USA, south through the Baja California Peninsula in Mexico. They are the most common Mouse species in the Baja California Peninsula, where they are found along the east coast of Baja California and throughout Baja California Sur. They also occupy ten islands in the Sea of Cortez and two islands in the Pacific Ocean. Their elevational range extends from sea level to approximately 900 m (3,000 feet). Spiny Pocket Mice inhabit rough desert landscapes with boulders, washes, rocky slopes, coarse soil, and sparse vegetation. On islands, they prefer rocky desert habitat.

The Spiny Pocket Mouse can be differentiated from Pocket Mice in other genera by their long, prominent spines on their backs.

From a conservation perspective, this species is currently considered to be of Least Concern due to their wide distribution and presumed large population size. No major threats have been identified for this species.