76 Sciurus vulgariscent of mortalities. Their alarm calls are a series of medium-
pitched barks or “chucks,” often followed by a long higher-
pitched whine. Eurasian red squirrels are a game animal
throughout their range. They are valued as food and are
hunted and trapped in much of their range. Furthermore,
their pelts are greatly desired, and a considerable market for
them exists, one that has led to serious conservation con-
cerns for populations in countries such as Mongolia. S. vul-
garis is often valued in parks and cities as an appealing wild-
life species. At a local scale, Eurasian red squirrels are also
considered to be a pest in gardens and orchards; their habit
of stripping bark to obtain cambium can result in a diminu-
tion of tree growth and vitality. Eastern gray squirrels (S.
carolinensis) have spread since they were introduced to Eng-
land, with a concomitant decline in the range and abun-
dance of Eurasian red squirrels. Eastern gray squirrels occur
at higher densities in broadleaf forests and form kin clusters
of related females. They nest in larger groups, digest acorns
more effi ciently, and accumulate fat more quickly than Eur-
asian red squirrels in some habitats. S. carolinensis pilfers the
caches of S. vulgaris; eastern gray squirrels also decrease
summer breeding and limit juvenile recruitment of the im-
periled native species. Furthermore, eastern gray squirrels
harbor parapoxvirus, which is fatal to Eurasian red squir-
rels but not to the invasive species. In addition, Eurasian red
squirrels appear very sensitive to fragmentation of their
habitat. Thus habitat loss and fragmentation constitute a sig-
nifi cant threat to S. vulgaris i n ma ny reg ions. Long-term con-
servation strategies will require wise and large-scale forest
management eff orts.
general references: Grill et al. 2009; Lurz et al. 2005;
Ognev 1963; Wauters, Bertolino, et al. 2005; Wauters, Tosi,
et al. 2002; Wauters, Vermeulen, et al. 2007.
Sciurus yucatanensis (Allen, 1877)
Yucatan Squirrel
description: The Yucatan squirrel has a black-and-white
to gray grizzled dorsum, often with a wash of olive brown
or tawny that appears rough in texture. A buff y postau-
ricular patch is often present. The feet are dark brown to
charcoal to black. The venter is buff to gray to grizzled
black and white. The tail is black at the core and frosted
with white to buff.
size: Both sexes—HB 200–322 mm; T 194–271 mm; Mass
341–475 g.
distribution: This species is found in the Yucatán Penin-
sula (México, northern and southwestern Belize, and north-
ern Guatemala).geographic variation: Three subspecies are recognized.S. y. yucatanensis—northern end of the Yucatán Peninsula
(México). This subspecies is the lightest in its dorsal and
ventral coloration.
S. y. baliolus—midsection of the Yucatán Peninsula (south-
ern Campeche, México). This is a lighter form, with a
buff y venter and a lack of distinct black patches at the
base of the ears.
S. y. phaeopus—southern Yucatán Peninsula (México, Be-
lize, and Guatemala). This is a dark form with black
legs, black patches at the base of the ears, and a grayish
venter.conservation: IUCN status—least concern. Population
trend—stable.habitat: The Yucatan squirrel occurs in deciduous and
evergreen forests, semiarid pine-oak (Pinus, Quercus) wood-
lands, and secondary forests; it also ranges into mangrove
swamps. S. yucatanensis can be found in coff ee and cacao
plantations.natural history: This species is diurnal. Yucatan squir-
rels are primarily arboreal; they are often seen moving