Tamiasciurus mearnsi 83to charcoal lateral stripe borders the white venter. The feet
are a pale yellowish white to gray, and the ear tufts are com-
posed of dense blackish tufts. A whitish eye ring is present.
The tail consists primarily of black hairs tipped with white
to gray to yellow.
size: Both sexes—HB 201.0 mm ± 13.2 mm.
distribution: This species is endemic to about 40,000^ ha
in the highest elevation of the Sierra de San Pedro Mártir in
northern Baja California (México). It is only known from
three locations.
geographic variation: None.
conservation: IUCN status—endangered. Population
trend—decreasing. T. mearnsi is considered threatened in
México.
habitat: This species is rest ric ted to l i m ited hig h-elevat ion
pine (Pinus) and fi r (Abies) forests.
natural history: The three sites from which Mearns’s
squirrels are known are within 10 km of each other, at eleva-
tions of 2100 m, 2500 m, and 2750 m. In stark contrast to its
two congeners (Tamiasciurus hudsonicus and T. douglasii), T.
mearnsi does not larder-hoard cones in middens or build
dreys in the canopy, instead relying on cavities for nests.
Males observed in May displayed scrotal testes, indicative of
reproductive activity. A mating bout was observed in May
as well, with as many as three males pursuing the female
that had a swollen pink vulva. Mearns’s squirrels feed upon
current-year cones of Jeff rey pine (Pinus jeff reyi) and white
fi r (Abies concolor), branch tips of white fi r, and the basidio-
mycete fungus veiled polypore (Cryptoporus volvatus), found
on the upper trunk of white fi rs. Three vocalizations are
known: a call similar to the territorial “rattle’’ of congeners
but of seemingly higher pitch, a “chirp’’ call when aggra-
vated, and a woofi ng bark or “buzz’’ call when startled or
mildly aggravated. Coyotes (Canis latrans), bobcats (Lynx ru-
fus), and raptors are probably this species’ major predators.Tamiasciurus mearnsi. Photo courtesy Bret Pasch.