Tamiasciurus hudsonicus

Red Squirrels are very vocal. They bark at intruders, including humans, and can bark continuously for more than an hour if they are annoyed. They also chatter, especially to stake out a territory and protect their stored food supply (conifer cones, which they harvest in great numbers) from other squirrels. They are especially noisy during the breeding season, when they chase each other through tree branches making a distinctive call that sounds almost like the buzz of cicadas. They readily nest in attics and cabins, and are trapped for their fur.

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Red squirrels are native to the Nearctic region and have one of the widest distributions of all North American squirrels. They are found from Alaska continuously across Canada to the northeast United States and south through the Appalachian states. They also occur throughout the Rocky Mountains.

Biogeographic Regions: nearctic (Native )

The range of the red squirrel extends from Quebec and Ontario west to
Alaska; south in the Appalachian Mountains to Tennessee; and south in
the Rocky Mountains to New Mexico [6].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

AK AZ CO CT DE ID IL IN IA KY ME MD MA MI MN MT NH NJ NM NY NC ND OH OR PA RI SC SD TN UT VT VA WA WV WI WY AB BC MB NB NF NT ON PQ SK YT

This species ranges widely in northern North America. It occurs from Alaska in the United States, eastward across Canada and southward to Arizona and New Mexico (in the west) and to extreme northern Georgia (in the east) in the United States. It is introduced to Newfoundland in eastern Canada.

Red squirrels are native to the Nearctic region and have one of the widest distributions of all North American squirrels. They are found from Alaska continuously across Canada to the northeast United States and south through the Appalachian states. They also occur throughout the Rocky Mountains.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Alaska to Newfoundland, south to the southern Appalachians and through the Rocky Mountains to Arizona and New Mexico.

Red squirrels have a total body length of from 280 to 350 mm, with the tail making up from 95 to 150 mm of that. Fur color is highly variable. Red squirrels in different part of their range can look quite different. Color changes between summer and winter as well. The fur on their back is usually brownish or olive-red in color. During the summer, a black stripe runs along their side, between the fur color of their back and their belly. The belly is white or cream color. The tail is often edged with white. There are white bands encircling their large, black eyes. The tail is not as thick or bushy as other North American tree squirrels. They are well adapted for climbing and running through the trees with compact, muscled bodies, strong claws, and powerful hind limbs.

Red squirrels might be confused with the young of Sciurus niger and Sciurus carolinensis. Red squirrels have a distinct white eye ring, which the other squirrel species lack. They are also distinguished by their extreme speed and agility, they zip around on trees and bushes, often while chattering loudly. The difference between the grey/red fur on their back and the white fur on their belly is often very distinct, another difference between these squirrels and other Sciurus species.

Range mass: 140 to 250 g.

Average mass: 194.5 g.

Range length: 280 to 350 mm.

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 1.615 W.

Red squirrels have a total body length of from 280 to 350 mm, with the tail making up from 95 to 150 mm of that. Fur color is highly variable. Red squirrels in different part of their range can look quite different. Color changes between summer and winter as well. The fur on their back is usually brownish or olive-red in color. During the summer, a black stripe runs along their side, between the fur color of their back and their belly. The belly is white or cream color. The tail is often edged with white. There are white bands encircling their large, black eyes. The tail is not as thick or bushy as other North American tree squirrels. They are well adapted for climbing and running through the trees with compact, muscled bodies, strong claws, and powerful hind limbs.

Range mass: 140 to 250 g.

Average mass: 194.5 g.

Range length: 280 to 350 mm.

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 1.615 W.

Length: 39 cm

Weight: 252 grams

Length:
Range: 280-350 mm

Weight:
Range: 140-250 g

Red squirrels are found in a variety of forested habitats, including coniferous, deciduous, and mixed forests. They can be found in suburban settings where there are large stands of mature trees.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: suburban

More info for the terms: cover, natural, tree

Nesting: Red squirrels prefer natural cavities or abandoned woodpecker
holes for nesting. When these are not available a leaf or grass nest is
constructed near the top of a tree with dense foliage. Occasionally red
squirrels use abandoned burrows of other species [6]. Nest trees in
Arizona have crowns that interlock with two or more adjacent trees, and
average 14 inches (35.6 cm) d.b.h. [47]. In New York leaf nests are
built in deciduous trees and pines. Trees used for leaf nests ranged
from 4 to 16 inches (10.2-40.6 cm) in diameter, were 15 to 70 feet
(4.5-21.3 m) tall, and the nests were 12 to 60 feet (3.7-18.3 m) above
the ground. Cavity trees ranged from 12 to 36 inches (30.5-91.4 cm) in
diameter and were 20 to 60 feet (6-18.3 m) tall; entrance holes were 7 to
50 feet (2.1-15 m) above the ground [25].

Shelter: Nest cavities are sometimes used by one to several red
squirrels in severe weather [25]. In winter red squirrels tunnel in
deep snow to find food and escape severe weather [3,13].

Cone-bearing Trees and Food Cache Sites: Red squirrels in Arizona
require 9 to 25 large, mature, cone-bearing trees (or a larger number of
smaller cone-bearing trees) per territory [27,47]. Red squirrels use
moist, shaded areas for the central food cache. These areas are created
by groups of mature trees with some understory vegetation nearby. Large
trees in a group closely spaced in 0.1 acre (0.04 ha) or less are
favored. Canopy cover at 90 percent of cache sites is greater than 60
percent. One or more large snags, fallen logs, or live trees act as
support structures for the cache [47].

In Pennsylvania primary red squirrel feeding sites (not caches) were
associated with burrow entrances, overstory cone-bearing pines, and
other primary feeding sites. They tended to be away from nest trees [50].

More info for the term: density

Red squirrels require mature coniferous trees as a source of cones and
seed [6]. The best cone production occurs in 200- to 300-year old
Douglas-fir, 40- to 300-year old white fir, and 150- to 200-year-old
Engelmann spruce. The best seed-producing stands of blue spruce (Picea
pungens) are 50 to 150 years old [31]. In central Colorado red
squirrels were present in closed stands of mature conifers [36]. In
west-central Colorado red squirrel caches were more abundant in
conifer-dominated stands than in mixed stands or in stands dominated by
quaking aspen [35]. In Ontario red squirrel tracks were more abundant
in uncut forest than in regenerating stands of various ages with brushy
understories [44].

In two study sites in central British Columbia red squirrels were twice
and over five times as abundant in unthinned stands of 20-year-old
lodgepole pine than in thinned stands. They were most abundant in
mature stands. It was suggested that the 20-year-old stands represented
marginal habitat that served as a sink area for excess juvenile red
squirrels [41].

Home Range: Red squirrel home range size varies with sex, age, and
habitat quality. Older red squirrels and females tend to have larger
home ranges. In lodgepole pine forests home ranges varied in size from
0.7 to 2.0 acres (0.3-0.8 ha); in mixed hardwood-conifer stands home
ranges varied from 6.5 to 11 acres (2.6-4.5 ha) [31]. Home ranges of
adult males in New York averaged 6.03 acres (2.4 ha) and ranged from
0.47 to 10.76 acres (0.2-4.3 ha) [25]. Davis [5] reported home ranges
of 3.2 acres (1.3 ha) for males and 3.7 acres (1.5 ha) for females.
Obbard [53] summarized other data on red squirrel home ranges.

Territoriality and Population Density: Red squirrels actively defend a
territory [18]. Gurnell [15] estimated that defended territories were
60 to 100 percent of the home range in lodgepole pine forests. In
British Columbia spruce-fir and hemlock-cedar (Thuja spp.) forests adult
territories averaged 2.2 acres (0.9 ha) at low elevations and 1.3 acres
(0.5 ha) at high elevations [52]. There are two types of defended
areas: most if not all red squirrels in Alberta defend a winter food
cache, which is usually abandoned during the summer, and some red
squirrels defend a "prime" territory which has an adequate food supply
year-round. One-quarter to one-third of adults defend a prime territory
[19]. In New Brunswick, where red squirrels are scatterhoarders instead
of larderhoarders, territories encompassing the entire food supply are
defended from conspecifics [7]. Smith [52] reported that defended red
squirrel territories in coniferous forests ranged from 0.5 to 3 acres
(0.2-1.2 ha).

Davis [5] reported red squirrel population density of 4 squirrels per 25
acres in mixed jack pine-black spruce stands and 23 red squirrels per 25
acres in white spruce forest. In southwestern Yukon Territory red
squirrel population densities of 27 per 25 acres (10 ha) and 17 per 25
acres were observed in white spruce forest interspersed with willow
(Salix spp.)-dominated meadows [29].

Many studies, reviewed by Klenner and Krebs [22], indicated that red
squirrel population density varies with cone crops. Zasada and others
[51] also suggested a relationship between red squirrel density and the
periodicity of white spruce cone production in Alaska since red
squirrels are dependent on white spruce cones for the majority of their
food. Rusch and Reeder [34] reported that summer populations fluctuated
between 67 and 151 red squirrels per 2,500 acres in mixed habitats.
Sullivan [40] reported that red squirrel population density in British
Columbia increased with food supplementation indicating that food
availability was limiting population density. In south-central British
Columbia food supplementation (feeders that were kept full of sunflower
[Helianthus spp.] seeds) in Douglas-fir and in white spruce forests
resulted in increases in red squirrel population densities. The amount
of change was greatest in the population occupying the Douglas-fir
stands, a low density population. Recruitment rates were very high
initially, but decreased with increasing population density. Each
population increased to approximately the same density, suggesting that
the factor regulating the maximum population density is not food supply
but territoriality. When feeders were removed, population density
declined to control levels in about 6 months [22].

More info for the terms: competition, hardwood

The red squirrel inhabits coniferous forests, mixed conifer-hardwood and
occasionally hardwood forests, and rural woodlots [6,19,13].

In western North America red squirrels occur in white spruce (Picea
glauca) and black spruce (P. mariana) stands [13,34], Douglas-fir
(Pseudotsuga menziesii) forests [22] and pine (Pinus spp.) forests [41].

In Alberta red squirrels occur in quaking aspen (Populus
tremuloides)-balsam poplar (P. balsamea) stands with scattered white
spruce and black spruce [19]. They also occupy habitats dominated by
jack pine (Pinus banksiana) with occasional stands of white spruce.
Tamarack (Larix laricina) bogs and black spruce bogs are usually
occupied only for periods by juvenile red squirrels searching for
suitable territories [13,24].

In Wyoming red squirrels are present in continuous whitebark pine (P.
albicaulis), Engelmann spruce (Picea engelmannii)-subalpine fir (Abies
lasiocarpa), and lodgepole pine (Pinus contorta) forests [18].

In Colorado red squirrels favor lodgepole pine forests over open stands
of ponderosa pine (P. ponderosa) [13]. They are also found in
Douglas-fir and in stands transitional between Douglas-fir and ponderosa
pine. Their absence from ponderosa pine stands may be a result of
interspecific competition with Abert's squirrels (Sciurus aberti).
Outside the range of Abert's squirrel, red squirrels are more common in
ponderosa pine stands (i.e., in Black Hills National Forest, South
Dakota, and Medicine Bow National Forest, Wyoming) [11].

In Arizona and Utah red squirrels prefer fir and spruce forests and are
more rarely found in ponderosa pine forests [13]. They are closely
associated with old-growth Douglas-fir, white fir (A. concolor), and
blue spruce (Picea pungens) stands [27]. Red squirrels are common in
low-elevation mixed species forests in central Arizona [46].

In eastern North America red squirrels are abundant in mature hardwood
forests containing some mature spruce (Picea spp.), eastern hemlock
(Tsuga occidentalis), or balsam fir (A. balsamea), but are rare in pure
hardwood stands that do not contain oaks (Quercus spp.), hickories
(Carya spp.), or walnuts (Juglans spp.) [25,53]. In the mountains of
Virginia red squirrels occur in Table Mountain pine (Pinus pungens)-oak
forests [45].

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: forb, hardwood

109 Ponderosa pine shrubland
409 Tall forb
809 Mixed hardwood and pine

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: bog

K001 Spruce-cedar-hemlock forest
K002 Cedar-hemlock-Douglas-fir forest
K004 Fir-hemlock forest
K005 Mixed conifer forest
K008 Lodgepole pine-subalpine forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K013 Cedar-hemlock-pine forest
K014 Grand fir-Douglas-fir forest
K015 Western spruce-fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K020 Spruce-fir-Douglas-fir forest
K021 Southwestern spruce-fir forest
K022 Great Basin pine forest
K028 Mosaic of K002 and K026
K093 Great Lakes spruce-fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce-fir forest
K097 Southeastern spruce-fir forest
K099 Maple-basswood forest
K100 Oak-hickory forest
K102 Beech-maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K107 Northern hardwoods-fir forest
K108 Northern hardwoods-spruce forest
K111 Oak-hickory-pine forest

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES14 Oak-pine
FRES15 Oak-hickory
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce-tamarack
14 Northern pin oak
15 Red pine
16 Aspen
18 Paper birch
19 Gray birch-red maple
20 White pine-northern red oak-red maple
21 Eastern white pine
22 White pine-hemlock
23 Eastern hemlock
24 Hemlock-yellow birch
25 Sugar maple-beech-yellow birch
26 Sugar maple-basswood
27 Sugar maple
30 Red spruce-yellow birch
31 Red spruce-sugar maple-beech
32 Red spruce
33 Red spruce-balsam fir
34 Red spruce-Fraser fir
35 Paper birch-red spruce-balsam fir
37 Northern white-cedar
38 Tamarack
40 Post oak-blackjack oak
51 White pine-chestnut oak
52 White oak-black oak-northern red oak
53 White oak
55 Northern red oak
78 Virginia pine-oak
107 White spruce
201 White spruce
202 White spruce-paper birch
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce-subalpine fir
208 Whitebark pine
209 Bristlecone pine
210 Interior Douglas-fir
211 White fir
212 Western larch
213 Grand fir
215 Western white pine
216 Blue spruce
218 Lodgepole pine
219 Limber pine
223 Sitka spruce
224 Western hemlock
225 Western hemlock-Sitka spruce
227 Western redcedar-western hemlock
228 Western redcedar
230 Douglas-fir-western hemlock
237 Interior ponderosa pine
251 White spruce-aspen
253 Black spruce-white spruce
254 Black spruce-paper birch

Habitat and Ecology

Systems

• Terrestrial

Red squirrels are found in a variety of forested habitats, including coniferous, deciduous, and mixed forests. They can be found in suburban settings where there are large stands of mature trees.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: suburban

Comments: Prefers coniferous and mixed forests, but also occurs in deciduous woodlots, hedgerows, second-growth areas. Prefers to nest in tree cavities; also constructs leaf nests and uses ground burrows.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Home range varies from 1-6 acres (Banfield 1974). In Alberta, most young settled close to mother's territory (maximum of 323 m from natal territory); of 219 births, only 20 offspring survived to the following spring (Larsen and Boutin 1994). In Minnesota, median dispersal distance for 8 young was 100 m, with 4 remaining in their natal ranges and 4 dispersing away (Sun 1997). In British Columbia, almost all juveniles settled on or adjacent to their natal territory (Haughland and Larsen 2004).

Red squirrels are not picky eaters. They consume seeds, fruit, nuts, bark, buds, shed antlers, Squamata, Insecta, tree sap, pine cones, fungi (including mushrooms that are poisonous to humans), Aves, Peromyscus leucopus, and young Sylvilagus floridanus. However, red squirrels eat primary the seeds of conifer trees. They may eat up to 2/3 of the pine seed crop in an area each year. Red squirrels store many seeds and nuts underground, in piles, or under rocks for the winter. They are able to relocate these buried seeds 30 cm underground and 4 meters below snow with their tremendous sense of smell. Many seed stockpiles are not recovered, however, making red squirrels a key tree planter and seed disperser.

Animal Foods: birds; mammals; eggs; insects; terrestrial non-insect arthropods

Plant Foods: roots and tubers; wood, bark, or stems; seeds, grains, and nuts; fruit; flowers

Other Foods: fungus

Foraging Behavior: stores or caches food

More info for the terms: competition, hardwood, tree

Red squirrels consume conifer seeds, nuts, buds, sap, tender leaves,
fruits, flowers, fungi, bird eggs, and small vertebrates [6]. In
captive trials white spruce seed alone sustained red squirrels for at
least 3 weeks. Red squirrels consumed seeds from an average of 144
cones per day per squirrel, probably more than they could consume in the
wild. Red squirrels lost weight on black spruce seed alone, and
preferred white spruce over black spruce seeds when presented with both
[2,3]. In Arizona each red squirrel was estimated to consume the seeds
of 42,000 to 131,000 pine cones per year [27,47]. On New Brunswick jack
pine sites, red squirrels consumed at least 47 cones per day [7].

In summer a larger array of foods is eaten, including elm (Ulmus spp.)
and maple (Acer spp.) seeds, raspberries (Rubus spp.) and other fruits,
and green cones of pines, Douglas-fir, hemlock, cedar, and larch (Larix
spp.). Some insects and nestling birds are also consumed [25]. In New
Hampshire red squirrels were observed preying on the eggs and young of
black-throated blue warblers (Dendroica caerulescens) [30]. Red
squirrels lap sap from trees damaged by yellow-bellied sapsuckers
(Sphyrapicus varius), and from other tree wounds [17]. They were also
observed licking sap and dried sugar from sap wells drilled by red-naped
sapsuckers (S. nuchalis) in Colorado [8]. In Vermont red squirrels were
observed biting holes in hardwood trees at periods associated with sap
flow. Sugar maple (Acer saccharum) was chosen more often than any other
tree. Rather than licking sap immediately, the red squirrels left the
fresh bite and returned at a later time, licking sap flows that had time
to evaporate into more concentrated sugar syrup or dried sugar. Sugar
spread by the researcher onto tree trunks did not immediately attract
red squirrels; it was inferred that red squirrels returned intentionally
to sap flows they had created [17].

The diet of the endangered Mount Graham red squirrel is not well known,
but is assumed to be similar to that of other red squirrels;
requirements include conifer seeds (mainly Engelmann spruce and
subalpine fir) and mushrooms [28].

In western North America cones are cached by red squirrels in a large
central location, often referred to as a midden (this type of food
storage is known as larderhoarding). Middens also contain other foods
such as seeds of other plant species, and mushrooms. Secondary middens
are also developed, usually at the base of a tree or tree cavity, but
are usually much smaller then the main midden [18,27]. Mushrooms are
sometimes left in tree branches and cached after they have dried [13].
It was suggested that larderhoarding may be a response to intense
predation in the winter; there is less movement involved in retrieving
cones from a cache than in searching for cones all winter [7].

In Wyoming red squirrels spent most of their foraging time in whitebark
pine forests finding and eating whitebark pine seed from cones or
recovering dropped whitebark pine seed. Cone harvesting may begin as
early as July 13 and cone caching usually begins by August 4. Red
squirrels often leave cones on the ground below the tree for up to 3
days before caching them [18]. In Colorado red squirrels appear to
prefer Douglas-fir cones over ponderosa pine cones; this may be a result
of interspecific competition with Abert's squirrels which require
ponderosa pine cones and bark [11]. In the Southwest commonly eaten and
preferred seeds include those of Douglas-fir, blue spruce, Engelmann
spruce, and white fir. Ponderosa pine seed is occasionally eaten in
Arizona [31].

In eastern North America red squirrels in conifer-dominated forests have
diets similar to those in western North America. In Maine red squirrels
remove northern white-cedar (Thuja occidentalis) branchlets and cones in
the fall, and consume branchlets with reproductive buds in the spring
[4]. Winter foods include terminal buds of conifers, boxelder (Acer
negundo) and red pine (Pinus resinosa) seeds, buds and sap of red maple
(A. rubrum), gray birch (Betula populifolia) and sugar maple, corn (Zea
mays), seeds of basswood (Tilia americana), sugar maple, silver maple
(A. saccharinum), Norway maple (A. platanoides), northern red oak
(Quercus rubra) and other oaks, hickory nuts, and butternuts (Juglans
cinera). Eastern hemlock (Tsuga canadensis) cones are a staple item in
some areas. Other winter foods include yellow-poplar (Liriodendron
tulipifera) and sycamore (Platanus occidentalis) seeds, fruits of
staghorn sumac (Rhus typhina) and smooth sumac (R. glabra), and bark.
In April and May red squirrels consume tree buds and flowers,
particularly those of American elm (Ulmus americana), sugar maple,
silver maple, Norway maple, northern red oak, and butternut [13,25,32].

In New Brunswick red squirrels are scatterhoarders rather than
larderhoarders; food is stored in small amounts in many places rather
than in one central midden. Red squirrels stored cones from both
serotinous and nonserotinous species: jack pine in central Ontario;
black, white, and red spruce (Picea rubens) in New Brunswick; and black
and red spruce in Maine. Cached cones are not sufficient for an entire
winter food supply; however, jack pine cones remain closed for at least
1 year and are retained on the tree for up to 7 years and therefore
provide a steady supply of winter food [7]. In Pennsylvania researchers
could not locate cone caches in marginal red squirrel habitat dominated
by aspens (Populus spp.). Red squirrels used a central location for
consuming cones; these feeding areas have been identified by the remains
of up to 103 cones [50].

Red squirrels are not picky eaters. They consume seeds, fruit, nuts, bark, buds, shed antlers, reptiles, insects, tree sap, pine cones, fungi (including mushrooms that are poisonous to humans), eggs, young birds, mice, and young rabbits. However, red squirrels eat primary the seeds of conifer trees. They may eat up to 2/3 of the pine seed crop in an area each year. Red squirrels store many seeds and nuts underground, in piles, or under rocks for the winter. They are able to relocate these buried seeds 30 cm underground and 4 meters below snow with their tremendous sense of smell. Many seed stockpiles are not recovered, however, making red squirrels a key tree planter and seed disperser.

Animal Foods: birds; mammals; eggs; insects; terrestrial non-insect arthropods

Plant Foods: roots and tubers; wood, bark, or stems; seeds, grains, and nuts; fruit; flowers

Other Foods: fungus

Foraging Behavior: stores or caches food

Primary Diet: omnivore

Comments: Diet consists of seeds, conifer cones, nuts, fruits. Occasionally feeds on invertebrates and small vertebrates. Commonly caches, and later consumes, large amounts of food; characterized by larderhoarding in the west, scatterhoarding in the east (Dempsey and Keppie, 1993, J. Mamm. 74:1007-1013). Also taps maple trees and consumes sugar residues (Heinrich, 1992, J. Mamm. 73:51-54).

Red squirrels can have a large impact on tree populations in two ways. They can severely limit the regrowth of conifer trees because they eat so many of their seeds. However, through their activities they also distribute the spores of beneficial fungi that help trees to acquire nutrients and grow and they accidentally plant the seeds of young trees, improving their chances of growing. Red squirrels are important prey animals for many small predators because of their abundance in the habitats in which they live.

Ecosystem Impact: disperses seeds

Red squirrels are quick and agile and can escape predators by taking refuge in thick vegetation or in the trees. Red squirrels are also fairly aggressive small animals and will defend themselves if cornered.

Known Predators:

• owls (Strigiformes)
• hawks (Accipitridae)
• weasels (Mustela)
• snakes (Serpentes)
• red foxes (Vulpes_vulpes)
• bobcats (Lynx_rufus)
• Canada lynx (Lynx_canadensis)
• American martens (Martes_americana)

The main predators of red squirrels in Alberta are raptors, probably
principally northern goshawk (Accipiter gentilis) [24]. Other red
squirrel predators include red-tailed hawk (Buteo jamaicensis), red fox
(Vulpes vulpes), bald eagle (Halieaatus leucocephalus), marten (Martes
americana), lynx (Lynx lynx) and ermine (Mustela erminea) [13,44]. Lynx
prey slightly more heavily on red squirrels in summer than winter (2% of
lynx winter diet, 9% of summer diet) [13]. Red squirrels comprised 5.6
percent of 36 prey deliveries to northern goshawk nests and 17.5 percent
of pellets (in 8 nests). More than 100 red squirrels were taken per
season by a single pair of breeding northern goshawks [31].

In Yellowstone National Park martens use the subnivean zone to get to
their prey which includes red squirrel. Red squirrels comprised 25
percent by volume of marten scats [37].

Red squirrels can have a large impact on tree populations in two ways. They can severely limit the regrowth of conifer trees because they eat so many of their seeds. However, through their activities they also distribute the spores of beneficial fungi that help trees to acquire nutrients and grow and they accidentally plant the seeds of young trees, improving their chances of growing. Red squirrels are important prey animals for many small predators because of their abundance in the habitats in which they live.

Ecosystem Impact: disperses seeds

Red squirrels are quick and agile and can escape predators by taking refuge in thick vegetation or in the trees. Red squirrels are also fairly aggressive small animals and will defend themselves if cornered.

Known Predators:

• owls (Strigiformes)
• hawks (Accipitridae)
• weasels (Mustela)
• snakes (Serpentes)
• red foxes (Vulpes vulpes)
• bobcats (Lynx rufus)
• Canada lynx (Lynx canadensis)
• American martens (Martes americana)

Tamiasciurus hudsonicus is prey of:
Bubo virginianus

Based on studies in:
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.

Tamiasciurus hudsonicus preys on:
Corylus
Populus
Pyrola
Cornus
Aralia
Pryola
Sitta canadensis
Sitta pygmaea
Certhia americana
Dendroica petechia
Junco hyemalis

Based on studies in:
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.

More info for the terms: prescribed fire, succession

Kirkpatrick and Mosby [20] suggested that prescribed fire in southern
pine-hardwood sapling and older stages is unlikely to affect resident
tree squirrels. This may apply to red squirrels, since important
habitat includes mature trees unlikely to be adversely affected by
low-severity fire. Fire severe enough to cause basal fire wounds may
increase cavities available for food caches. Basal fire wounds are
unlikely to increase cavities useful as nests for red squirrels [20].

In Yellowstone National Park lodgepole pine stands monitored for
presence of birds and mammals during postfire succession, red squirrels
were only present in stands with closed canopies [42]. In north-central
Colorado red squirrels were not present on 8-year-old burned areas but
were present in adjacent unburned lodgepole pine stands [33].

The maintenance of many mature coniferous forest types is often
dependent on fire. Ponderosa pine, Douglas-fir, lodgepole pine,
whitebark pine, and spruces are either dependent on stand-replacing
fires for regeneration or on low-severity fires for maintenance. Even
though severe fire is immediately destructive of red squirrel habitat,
the long-term maintenance of most coniferous forests is dependent on
fire [57].

More info for the terms: litter, tree

Diurnal Activity: Red squirrels are diurnal and active year-round. Peak
activity occurs 2 hours after sunrise and just before sunset, but
red squirrels are active most of the daylight hours [25].

Movement: Rusch and Reeder [34] reported that red squirrels move from
quaking aspen and pine stands to spruce stands in the spring. Fall
movements are largely those of juveniles moving away from denser
populations of adults in spruce stands.

Breeding Season: Red squirrel breeding season varies with latitude and
elevation. Generally, the breeding season peaks from March to August,
but breeding may begin as early as January and continue as late as
October. Mating is promiscuous [13,25].

Nesting and Litter Size: Female red squirrels prefer to nest in natural
tree cavities or abandoned woodpecker (Picidae) holes. If none are
available they build a leaf [25] or grass nest [27] in the crotch of a
limb high on a densely foliated tree, or use a fallen tree, rock pile,
underground burrow, or man-made structure. There are usually four or
five young per litter (range: one to eight). Generally there is only
one litter per year, but occasionally a female bears two litters in one
year [25].

Development of Young: Red squirrel young are born naked and blind. By
6 days there is noticeable fur growth and by 20 days there is a good
covering of dorsal fur. Their eyes open at 27 to 35 days. They are
mostly furred by about 8 weeks. The young red squirrels begin making
limited excursions from the nest at 6 to 7 weeks, and forage at a
greater distance by about 10 weeks [25]. Weaning occurs at about 7 to 8
weeks in New York [25] and about 10 weeks in Alberta [24]. Dispersal
usually begins at about 12 to 14 weeks [25]. Female red squirrels in
Canada usually do not breed until their second year. Males develop
scrotal testes their first spring but it is not known whether they breed
at that time [24].

Dispersal of Juveniles: Juvenile red squirrels disperse in the fall in
search of suitable territory [21]. In Alberta initial movements are
circular; unsuccessful juveniles usually return to the natal territory
until they are successful or are killed. Occasionally juveniles will
appropriate the mother's territory [24]. Survival of juveniles depends
on establishment of a territory with a food supply adequate for the
entire winter [22]. Juveniles surviving their first winter tended to be
relatively far away from the natal territory. They appeared to have
acquired larger territories than juveniles that died, with middens that
were constructed by previous owners [24].

Red squirrels tend to disperse and establish territories in relation to
major resources (mature cone-bearing trees) [22]. In south-central
British Columbia relocation of resident adult squirrels a substantial
distance from the study site allowed researchers to monitor red squirrel
recruitment rates. In the fall red squirrel population density
recovered to control levels on four out of six sites; immigrants were
mostly juveniles. In the spring, breeding red squirrel population
density recovered to control levels on five out of the six sites; these
sites were also colonized by juveniles in the fall [21].

Mortality and Longevity: In Alberta average annual mortality was 67
percent for juveniles, 34 percent for adult yearlings, and 61 percent
for older adults [19]. Larsen and Boutin [24] reported annual adult
survivorship for red squirrels in Alberta as 67 to 71 percent. Captive
red squirrels have lived at least 9 years and wild red squirrels have
lived at least 10 years [25].

Densities range from about 1 per 3.2 ha (Pinaleno Mountains, southeastern Arizona) to 1 per 0.2 ha (Layne 1954, USFWS 1987).

More territorial than most other North Amerian tree squirrels. Some populations in British Columbia are limited by food (acting through effect on reproduction) (Sullivan 1990; see also J. Mamm. 73:930-936); but factors such as territorial behavior may limit populations at high density (Klenner and Krebs 1991, Klenner 1991).

Sciurid mycophagy may play important role in forest ecology (Maser and Maser 1988).

Red squirrels have keen senses of smell, sight, and hearing. They are very vocal and loudly scold intruders in their home range. Vocalizations consist of rattles, screeches, growls, buzzes, and chirps.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Red squirrels have keen senses of smell, sight, and hearing. They are very vocal and loudly scold intruders in their home range. Vocalizations consist of rattles, screeches, growls, buzzes, and chirps.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Comments: Usually quite conspicuous throughout the day. Most active 2 hours after sunrise and before sunset.

Red squirrels can live up to 7 years in the wild, though most will die before they are 1 year old. One captive red squirrel lived 9.8 years.

Range lifespan
Status: wild: 7 (high) years.

Range lifespan
Status: captivity: 9.8 (high) years.

Average lifespan
Status: captivity: 9.8 years.

Red squirrels can live up to 7 years in the wild, though most will die before they are 1 year old. One captive red squirrel lived 9.8 years.

Range lifespan
Status: wild: 7 (high) years.

Range lifespan
Status: captivity: 9.8 (high) years.

Average lifespan
Status: captivity: 9.8 years.

Maximum longevity: 9.8 years (captivity) Observations: One captive specimen lived 9.8 years (Richard Weigl 2005).

In warmer climates there are two breeding seasons, in the late winter and mid-summer. In colder climates, there is only one which begins at the spring thaw, from mid-January to mid-February. She gives birth, after a 33 to 35 day pregnancy, in a lined den or tree hollow, to from 1 to 8 young. Litter size is typically 2 to 5. The young develop very quickly and are weaned 7 to 8 weeks after birth. At 40 days old they leave the nest. Juvenile mortality is high, with owls, hawks, and pine martens taking many individuals. About 25% survive to adulthood, which is achieved around one year after young are born.

Breeding interval: Red squirrels can breed several times in the breeding season.

Breeding season: Breeding is from mid-January to mid-February.

Range number of offspring: 1 to 8.

Range gestation period: 33 to 35 days.

Range weaning age: 7 to 8 weeks.

Average age at sexual or reproductive maturity (female): 1 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 7 g.

Average number of offspring: 4.2.

Average age at sexual or reproductive maturity (female)
Sex: female: 342 days.

Females care for and nurse their young in the nest for 40 days. In the fall following their birth the young disperse from their mother's home range.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

In warmer climates there are two breeding seasons, in the late winter and mid-summer. In colder climates, there is only one which begins at the spring thaw, from mid-January to mid-February. She gives birth, after a 33 to 35 day pregnancy, in a lined den or tree hollow, to from 1 to 8 young. Litter size is typically 2 to 5. The young develop very quickly and are weaned 7 to 8 weeks after birth. At 40 days old they leave the nest. Juvenile mortality is high, with owls, hawks, and pine martens taking many individuals. About 25% survive to adulthood, which is achieved around one year after young are born.

Breeding interval: Red squirrels can breed several times in the breeding season.

Breeding season: Breeding is from mid-January to mid-February.

Range number of offspring: 1 to 8.

Range gestation period: 33 to 35 days.

Range weaning age: 7 to 8 weeks.

Average age at sexual or reproductive maturity (female): 1 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 7 g.

Average number of offspring: 4.2.

Average age at sexual or reproductive maturity (female)
Sex: female: 342 days.

Females care for and nurse their young in the nest for 40 days. In the fall following their birth the young disperse from their mother's home range.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Breeds March-April and June-July in Quebec. Gestation lasts 31-35 days (Lair 1985). Some females produce 2 litters/year; litter size averages 4-5. Some females breed when less than one year old (Lair 1986).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 11 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 9
Specimens with Barcodes: 29
Species With Barcodes: 1

Red squirrels are common and not currently threatened throughout most of their range. A subspecies, the Mt. Graham red squirrel in southeastern Arizona, has been reduced to 150 individuals and is listed as endangered. A new observatory complex, campgrounds, and continued logging threatens its last habitat.

IUCN Red List of Threatened Species: least concern

US Federal List: endangered; no special status

CITES: no special status

State of Michigan List: no special status

Information on state- and province-level protection status of animals in the
United States and Canada is available at NatureServe, although recent changes
in status may not be included.

The Mount Graham red squirrel (T. h. ssp. grahamensis)is Endangered [45].

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Lower Risk/least concern
  (Baillie and Groombridge 1996)

Red squirrels are common and not currently threatened throughout most of their range. A subspecies, the Mt. Graham red squirrel in southeastern Arizona, has been reduced to 150 individuals and is listed as endangered. A new observatory complex, campgrounds, and continued logging threatens its last habitat.

US Federal List: endangered; no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread in North America; abundant in many areas.

The Mount Graham red squirrel, T. hudsonicus grahamensis, is Critically Endangered.

Population

Population Trend

Major Threats

More info for the terms: cover, formation, natural, selection, tree

Red squirrels are considered pests in some areas where they consume a
large proportion of available conifer seeds. It has been suggested that
they interfere with natural regeneration of conifers by removing most of
the seed crop; this is particularly detrimental in years with poor cone
crops [12,13,51]. Cached seed and cones do not usually germinate; a
seed fungus (Caloscypha fulgens), which appears to prevent germination
and rotting of seeds, is encouraged by the moist, cool conditions
usually found in red squirrel cache sites [53,54]. In Newfoundland red
squirrels are a recent introduction and have become a serious threat to
black spruce cone harvests for commercial seed production [48]. Red
squirrels clip (and often consume) terminal buds and peel the bark of
trees, occasionally girdling stems. Gnawing damage to trees sometimes
causes canker formation [13]. In Arizona red squirrels harvested more
than 80 percent of limber pine (Pinus flexilis) cones before the cones
opened (making the seeds unlikely to germinate even if they are not
consumed); in open sites where red squirrels were absent more than 70
percent of cones opened on the trees [9].

In Newfoundland harvesting black spruce cones in August or September is
recommended in order to anticipate removal of cones by red squirrels
[48]. In central British Columbia thinning of 20-year-old lodgepole
stands resulted in a reduction in red squirrel populations but did not
appreciably lower the amount of tree damage inflicted by red squirrels
gnawing on bark [41].

Red squirrels and other mycophagous species probably play an important
role in the dispersal of the spores of mycorrhiza-forming fungi and
therefore benefit conifer reproduction [26]. Red squirrel middens are a
source of conifer seed for forestry in some western states [12,13].

Habitat management: Red squirrels are dependent on mature conifers for
food and cover. Conifer plantings in suburban areas tend to encourage
red squirrels. Red squirrels will use nest boxes if they are placed in
suitable habitat [13]. Vahle and Patton [27,47] recommended maintenance
of areas with closely spaced groups of trees of different ages and sizes
for red squirrel habitat. Conifers larger than 15 inches (38 cm) d.b.h.
are necessary for cone production; at least three or four large trees
per acre are needed. Timber harvest using group selection promotes
habitats favored for red squirrel cache sites [47]. Reynolds and others
[31] listed specific management recommendations for red squirrels in the
Southwest in conjunction with maintenance of northern goshawk prey base.

Black bears (Ursus americanus) damaged trees adjacent to Mount Graham
red squirrel middens more often than at random locations. This damage
frequently kills the tree. Death of the tree results in loss of cone
production, but it also provides snags for nest cavities and storage
sites [39]. The endangered grizzly bear (U. arctos horribilis)
excavates red squirrel cone caches in whitebark pine stands; this is an
important grizzly bear food source in some areas. Grizzly bear habitat
management includes encouragement of both whitebark pine and red
squirrel [56].

Red squirrels are economically important furbearers in Canada [19,53].
More red squirrels are taken but the total value is less than that of
other furbearers [53].

Parasites and diseases of red squirrels were summarized by Layne [25]
and Flyger and Gates [13].

Conservation Actions

Red squirrels can severely damage young trees in plantations, and crops in storage. They may also gnaw on many household items and can become a nuisance if they nest in homes.

Negative Impacts: crop pest; household pest

Red squirrels are beneficial because of their dispersal of tree seeds and the spores of fungi required by many trees for successful growth. About 1 to 3 million red squirrels are harvested annually for their fur in Canada, bringing in about $1 million. They are a major prey item for other economically important species such as martens, bobcats, and lynx.

Positive Impacts: body parts are source of valuable material

Red squirrels can severely damage young trees in plantations, and crops in storage. They may also gnaw on many household items and can become a nuisance if they nest in homes.

Negative Impacts: crop pest; household pest

Red squirrels are beneficial because of their dispersal of tree seeds and the spores of fungi required by many trees for successful growth. About 1 to 3 million red squirrels are harvested annually for their fur in Canada, bringing in about $1 million. They are a major prey item for other economically important species such as martens, bobcats, and lynx.

Positive Impacts: body parts are source of valuable material