Mearns's squirrel

Mearns's squirrel is a relatively small tree squirrel, with an average head-body length of 20 cm (7.9 in), and weighing about 270 g (9.5 oz). They have soft, dense, fur, which is grey-brown on the upper body and white with yellow patches on the underparts. There is a stripe of solid black fur on each flank, and a narrow band of reddish-yellow fur runs down the middle of the back. The tail is bushy, with darker fur than the body, but fringed with white and yellow. The fur on the head is mostly grey, becoming yellowish towards the snout, and with dark ears and clear rings of white fur around the eyes.[4]

Mearns's squirrel is known from only three sites in the Sierra de San Pedro Mártir in Baja California, Mexico.[4] The region is surrounded by areas of chaparral and desert, isolating the tree squirrel from its closest relatives elsewhere, and indicating that it is likely a relict population isolated by forest fragmentation during the Pleistocene.[5] The three sites all consist of pine and fir forests at altitudes of 2,100–2,400 m (6,900–7,900 ft),[1] and cover an area of no more than 40,655 ha (157 sq mi).[4]

Mearns's squirrel is diurnal and herbivorous, feeding mainly on the seeds of fir and pine trees. Unlike its closest relatives, such as the Douglas squirrel, it does not hoard food for future use,[3] and it rests in cavities in trees, rather than constructing nests from leaves.[6] The squirrels do not appear to be territorial, and two individuals may sometimes share the same resting cavity.[7] Vocalizations are known to include a high-pitched "rattle", a chirp, and a barking sound.[8]

The mating season lasts from around February to August, with one or two litters of two to five young being born each year.[4]