48 Sciurus colliaeisize: Female—HB 243.4 mm; T 260.4 mm; Mass 440.8 g.
Male—HB 248.6 mm; T 243.2 mm; Mass 335.2 g.
Sex not stated—HB 266.1 mm; T 274.1 mm.
distribution: This species occupies a narrow area along
the westcentral coast of México, from the states of Sonora
and Chihuahua to Sinaloa, Durango, Nayarit, Jalisco, and
Colima.
geographic variation: Four subspecies are recognized.
S. c. colliaei—Nayarit (México). See description above.
S. c. nuchalis—Jalisco and Colima (México). This subspecies
has a yellowish nape, a black rump, and ears that are
more yellow or rust colored than those of S. c. colliaei.
S. c. sinaloensis—Sinaloa (México). This subspecies has a
larger skull than S. c. colliaei.
S. c. truei—Sonora, Chihuahua, and Sinaloa (México). The
skull is broader and the cranium is fl atter than in S. c.
colliaei.
conservation: IUCN status—least concern. Population
trend—no information.
habitat: This species is found in thick tropical and sub-
tropical vegetation in the coastal plain of the central Pacifi c
coast of México, where it is reported to occupy a number of
forest types, especially in Jalisco. It sometimes occurs in
canyons and at lower elevations (up to 2000 m). It is often
associated with fi gs (Ficus) and palms (e.g., Orbignya cohune),
upland oak (Quercus) forests, and riparian or tropical dry for-
ests (i.e., arroyo forests) of the Pacifi c coast. In the northern
part of its range, Collie’s squirrel often occupies subtropical
canyons.natural history: Collie’s squirrel appears to specialize
on the fruits and nuts of palms, fi gs (Ficus), and possibly
oaks (Quercus). Forest fragmentation seems to reduce the
distribution of this species, as measured by patterns of fruit
predation in continuous and fragmented forests; in frag-
mented forests only 34 percent of Ceiba aesculifolia trees sus-
tain fruit damage by S. colliaei, whereas 100 percent of these
trees experience squirrel damage in continuous forests. Col-
lie’s squirrel is primarily (but not exclusively) arboreal. It is
diurnal: active mostly in the morning (just after sunrise) and
again late in the day (until sunset). This species is reported
to build dreys on outer tree branches, but also to form nests
in cavities in tree trunks and in abandoned arboreal termite
nests. This species appears to breed in March and April, and
its young have been reported in April in two parts of its
range (Jalisco and Sonora). However, two females have been
reported with embryos (three each): one in late May (Chi-
huahua), and another in mid-June (Durango). Hence more
detail is needed on the reproductive biology of this species.
The shape and size of the baculum are similar to the bacula
of several other species of Mexican Sciurus (e.g., S. aureo gaster,
S. variegatoides, and S. yucatanensis). S. aureogaster is closely
related to S. colliaei, and the others were considered part of
the same fragmented species complex in the past, based on
similarities in pelage, cranial features, and ecology. Collie’sSciurus colliaei. Photo courtesy Petr Myska, vivanatura.org.