Index of Species Information
WILDLIFE SPECIES: Ursus arctos horribilis
Introductory
WILDLIFE SPECIES: Ursus arctos horribilis
AUTHORSHIP AND CITATION :
Snyder, S. A. 1991. Ursus arctos horribilis. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
www.fs.usda.gov/database/feis/animals/mammal/urach/all.html [].
ABBREVIATION :
URARH
COMMON NAMES :
grizzly bear
grizzly
brown bear
TAXONOMY :
The currently accepted scientific name for grizzly bear is Ursus arctos
horribilis. It is 1 of 6 subspecies of brown bear (Ursus arctos). Other
North American subspecies of brown bear include [6]:
Ursus arctos alascensis, Alaskan brown bear
Ursus arctos gyas, peninsular brown bear
Ursus arctos middendorffi, Kodiak bear
Ursus arctos stickensis, Sitka brown bear or ABC Island bear
Ursus arctos stikeenensis, Sitkine brown bear
ORDER :
Carnivora
CLASS :
Mammal
FEDERAL LEGAL STATUS :
The grizzly bear is listed as Threatened in most of the conterminous
United States. Grizzly bears in Idaho and Montana are listed as an
Experimental Population, Non-Essential. Populations in the North Cascades
Ecosystem are Under Review for listing. Cabinet-Yaak populations are Under
Review for listing as Endangered [42].
OTHER 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.
WILDLIFE DISTRIBUTION AND OCCURRENCE
WILDLIFE SPECIES: Ursus arctos horribilis
GENERAL DISTRIBUTION :
The grizzly bear ranges from Alaska east through the Yukon and Northwest
Territories, south through British Columbia and through the western half
of Alberta. Isolated populations exist in northwestern Washington,
northern Idaho, western Montana, and northwestern Wyoming. Ursus
a. horribilis includes all brown bear of continental North
America; U. a. ssp. middendorffi includes brown bear on the Alaskan
islands of Kodiak, Afognak, and Shuyak. U. a. ssp. nelsoni's range is
in northern Mexico [6].
ECOSYSTEMS :
FRES11 Spruce-fir
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES29 Sagebrush
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES44 Alpine
STATES :
| AK |
ID |
MT |
WA |
WY |
|
AB |
BC |
MB |
YK |
MEXICO |
BLM PHYSIOGRAPHIC REGIONS :
8 Northern Rocky Mountains
9 Middle Rocky Mountains
KUCHLER PLANT ASSOCIATIONS :
K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - 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
K018 Pine - Douglas-fir forest
K020 Spruce - fir - Douglas-fir forest
K050 Fescue - wheatgrass
K052 Alpine meadows and barren
K063 Foothills prairie
SAF COVER TYPES :
16 Aspen
18 Paper birch
109 Hawthorn
201 White spruce
202 White spruce - paper birch
203 Balsam poplar
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce - subalpine fir
208 Whitebark pine
210 Interior Douglas-fir
212 Western larch
213 Grand fir
215 Western white pine
217 Aspen
218 Lodgepole pine
219 Limber pine
221 Red alder
222 Black cottonwood - willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock - Sitka spruce
226 Coastal true fir - hemlock
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock
235 Cottonwood - willow
237 Interior ponderosa pine
251 White spruce - aspen
252 Paper birch
253 Black spruce - white spruce
254 Black spruce - paper birch
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
PLANT COMMUNITIES :
Although timber is an important habitat component, grizzly bear prefer
more open habitats. Timbered plant communities most frequented by
grizzly bear include subalpine fir (Abies lasiocarpa)-whitebark pine
(Pinus albicaulis), lodgepole pine (P. contorta)-Douglas-fir
(Pseudotsuga menziesii), and spruce (Picea spp.)-western redcedar (Thuja
plicata)-hemlock (Tsuga spp.) forests. Sedge (Carex spp.)-bluegrass
(Poa spp.) meadows are also important, as well as shrubfields and low- and
high-elevation riparian communities [3,23,36,39].
BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Ursus arctos horribilis
TIMING OF MAJOR LIFE HISTORY EVENTS :
Mating Season - breed every 2 to 3 years; May through July
Birthing Season - late November through February; one to four cubs, two
is common
Gestation - 6 to 7 months with delayed implantation
Age of Maturity - 5 to 8 years for females
Life Span - 25 years or more in captivity
Denning - between October and May; length of time depends on food
availability, weather conditions, and sex of animal; may emerge
if disturbed by human activity
[6,17,31]
PREFERRED HABITAT :
Grizzly bear prefer open, shrub communities, alpine and low elevation
meadows, riparian areas, seeps, alpine slabrock areas, and avalanche
chutes [32,36,38]. They typically choose low elevation riparian sites,
wet meadows, and alluvial plains during spring [28,36]. During summer
and fall grizzly bear more frequently use high elevation meadows,
ridges, and open, grassy timbered sites [28,32]. Various authors have
mapped and evaluated grizzly bear habitat [5,30,35].
COVER REQUIREMENTS :
Optimal grizzly bear cover is wooded areas interspersed with grass- and
shrubland. Ruediger and Mealy [29] defined hiding cover as that which
is capable of hiding an animal at 200 feet (61 m) or less in an area of
30 to 50 acres (12-20 ha). Thermal cover was defined as coniferous
trees at least 40 feet (12 m) tall with a 70 percent canopy cover in a
7- to 50-acre (3-20 ha) area. These authors recommended maintaining 30
percent of grizzly bear habitat as cover. McLellan [22] stated that not
enough significance is given to timbered areas as components of grizzly
bear habitat. Graham [13] found that in Yellowstone National Park,
grizzly bear preferred open areas that were within 160 feet (50 m) of
cover. McLellan and Shakleton [23] reported that the bears use areas
within 300 feet (100 m) of roads during the day, but that darkness is
sufficient "cover" for road use at night. Grizzly bear use daybeds in
timbered areas that are near feeding sites [3,28]. Winter dens are
usually excavated in hillsides, although dens are also made in rock
caves, downfall timber, and beneath trees and stumps [6,31,36].
FOOD HABITS :
Grizzly bear primarily eat grasses, forbs, roots, tubers, and fruits.
They also eat carrion, grubs, insects, particularly army cutworm moths
(Noctuidae) and ladybird beetles (Coccinelidae), fish, small rodents,
various bird species, and garbage [39]. Adult males also prey on
subordinate grizzly bear and on black bear [14]. Orchards, beehives,
and crops may be damaged by grizzly bear; they may also prey on
livestock [17,32]. Some of the more common plant foods are russet
buffaloberry (Shepherdia canadensis), Saskatoon serviceberry (Amelanchier
alnifolia), Sitka mountain-ash (Sorbus sitchensis), snowberry
(Symphoricarpos spp.), hawthorn (Crataegus spp.), honeysuckle (Lonicera
spp.), whitebark pine seeds, pine (Pinaceae) vascular cambium, willow
(Salix spp.), dogwood (Cornus spp.), huckleberry and blueberry
(Vaccinium spp.), dandelion (Taraxacum spp.), sweetvetch (Hedysarum
spp.), clover (Trifolium spp.), cowparsnip (Heracleum spp.), glacier
lily (Erythronium grandiflorum), horsetail (Equisetum spp.), lomatium
(Lomatium spp.), kinnikinnick (Arctostaphylos uva-ursi), strawberry
(Fragaria spp.), buckthorn (Rhamnus spp.), paintbrush (Castelleja spp.),
thistle (Cirsium spp.), fritillary (Fritillaria spp.), boykinia
(Boykinia richardsonii), and sheathed cottonsedge (Eriophorum vaginatum)
[6,8,13,14,26,29,32,37,39].
PREDATORS :
Grizzly bear predators include humans and other grizzly bear [17].
MANAGEMENT CONSIDERATIONS :
Grizzly bear have a low reproductive rate and late maturation age which
makes them susceptible to overharvesting. Also, many grizzly bear are
poached or hit by cars and trains. Other factors contributing to the
bear's decline are habitat use and disturbance by humans, both for
commercial and recreational purposes; and fire control, which in some
instances can result in reduced acres of food-rich seral shrubfields
[17,19,33,38]. Grizzly bear have been known to prey on livestock where
their ranges overlap and occasionally kill humans as a result of chance
encounters, usually in the backcountry. Because of conflicts between
grizzly bear and humans, grizzly bear habitat should be isolated from
developed areas, preferably in areas that receive only light
recreational, logging, or livestock use [45].
Logging can benefit grizzly bear populations if silvicultural treatments
promote berry-producing shrubs. However, timber management effects
should be considered over the entire rotation because an increase in
shrubs may only redistribute grizzly bear and not increase their numbers
[27]. Logging can also increase human access to critical grizzly bear
habitat, disturbing populations. Roads should be located away from
feeding areas, such as shrubfields, wet meadows, and riparian zones.
Road and seasonal trail closures must also be enforced [27,29].
Scarification and dozer pile burning can disturb soil and kill valuable
food shrubs [38]. Several authors list timber management
recommendations and road construction guidelines in grizzly bear habitat
[25,28,37,39,41].
FIRE EFFECTS AND USE
WILDLIFE SPECIES: Ursus arctos horribilis
DIRECT FIRE EFFECTS ON ANIMALS :
Direct fire-related mortality probably occurs but may not have a
significant impact on the grizzly bear population as a whole [44].
HABITAT RELATED FIRE EFFECTS :
Many authors have blamed fire suppression in some areas for the decline
of grizzly bear [7,25,35,36]. Fires can promote and maintain many
important berry-producing shrubs and forbs, as well as provide a medium
for insects and in some cases carrion. Referring to the Yellowstone
National Park fires of 1988, Blanchard and Knight [44] stated: "The most
important apparent immediate effect of fires on grizzly bears was the
increased availability of some food items, especially carcasses of elk."
Studies in western Montana showed that spring burning in
Douglas-fir-ponderosa pine (Pinus ponderosa) types promoted huckleberry
sprouting [24]. The number of stems present after burning were closely
related to the number present before burning. Grouse whortleberry
(Vaccinium scoparium) declined following fire in western Montana because
its shallow rhizomes were killed by the heat [37,38]. In the same study
most shrubs occurred on sites burned 35 to 70 years previously. Martin
[21] found that huckleberry was most productive on sites burned between
25 to 60 years previously or on sites clearcut and burned 8 to 15 years
previously. Huckleberry on sites left untreated for more than 60 years
was least productive. Other shrubs that respond well to overstory
removal and broadcast burning are elderberry (Sambucus spp.), Sitka
mountain ash, serviceberry, and buffaloberry [15].
FIRE USE :
Fire can be used to create and maintain seral shrub communities for
grizzly bear by rejuvenating shrubs, releasing nutrients, and
discouraging conifer dominance [25,37]. In the case of postharvest
treatment, many authors recommend broadcast burning and discourage dozer
pile burning. The latter method can damage rhizomes, root crowns, and
the soil [4,16,29,37,39]. Natural fire programs as well as prescribed
burning for improved grizzly habitat are encouraged and practiced by
some National Forests [7,11,16,25,35]. Garcia [11] and Holland [16]
discuss burning practices on the Kootenai and Flathead National Forests.
A fire-induced increase of berry-producing shrubs may only be beneficial
if spread over large areas that encompass home ranges of several bears
[33]. However, prefire plant composition may dictate postfire
composition [24]. Berry-producing shrubs must be provided continually
over time to be beneficial [15]. Miller [24] recommends burning
huckleberry during spring in Montana Douglas-fir-western larch (Larix
occidentalis) communities. Also, burning should be conducted when duff
is damp; fires that remove most of the duff often reduce huckleberry
density.
FIRE REGIMES :
Find fire regime information for the plant communities in which this
animal may occur by entering "grizzly bear" in the FEIS home page under
"Find Fire Regimes".
REFERENCES
WILDLIFE SPECIES: Ursus arctos horribilis
REFERENCES :
1. Agee, James K.; Stitt, Susan C. F.; Nyquist, Maurice; Root, Ralph. 1989.
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FEIS Home Page
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