(DRAFT) - Taxonomy
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
TAXONOMY
NAME - sheep, Dall
OTHER COMMON NAMES - sheep, Dall's, sheep, white, Alaskan and sheep, thinhorn
ELEMENT CODE -
CATEGORY - Mammals
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - ,
ORDER AND SUBORDER - ,
FAMILY AND SUBFAMILY - ,
GENUS AND SUBGENUS - Ovis,
SPECIES AND SSP - dalli, dalli
SCIENTIFIC NAME - Ovis dalli dalli
AUTHORITY -
TAXONOMY REFERENCES - 232
Taxonomy - 1 (DRAFT) - Status
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
STATUS
Coded Status
Game (Consumptive Recreational)
See Comments
REFERENCES FOR STATUS - 232
COMMENTS ON STATUS -
Dall sheep in Alaska are managed as a game animal by the Alaska Department
of Fish and Game *232*.
Status - 1 (DRAFT) - Distribution
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
REFERENCES FOR HABITAT - 232
LAND USE -
Snow or Ice: All Classes
REFERENCES FOR LAND USE - 232
COMMENTS ON HABITAT ASSOCIATIONS -
Dall sheep occur in North America throughout the major mountain ranges of
Alaska. Sheep are capable of using all suitable habitat in the mountain
ranges they occupy. Typically, precipitous terrain with rocky slopes,
ridges, and cliffs is used. In early winter, sheep use lower-elevation
slopes. These slopes provide forage of good quality and quantity, even
though they are snow-covered. Mineral licks are recommended to be
considered critical habitat areas *232*.
ANIMAL/PLANT SPECIES ASSOCIATIONS -
Wolf
Bear
Coyote
Lynx
Golden eagles
REFERENCES FOR SPECIES ASSOCIATIONS - 232
COMMENTS ON SPECIES ASSOCIATIONS -
Wolves are a major predator in areas where the wolf population is high
and/or escape terrain is limited. Predation by bears, coyotes, lynx, and
other predators occurs, but the extent is unknown. Golden eagles are
thought to be serious predators of lambs during their first few weeks of
life *232*.
Major diseases and parasites associated with Dall sheep in Alaska include
contagious ecthyma, lungworm-pneumonia complex, mandibular osteomylitis
(lumpy jaw), and several species of gastro-intestinal helminth worms *232*.
Habitat Associations - 1 (DRAFT) - Food Habits
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
HERBIVORE/BROWSER
HERBIVORE/GRAZER
REFERENCES FOR TROPHIC LEVEL - 232
LIFESTAGE FOOD FOOD PART
General Poaceae Bole/Stem
General Poaceae Leaves/Needles
General Cyperaceae Bole/Stem
General Cyperaceae Leaves/Needles
General Plants Bole/Stem
General Plants Leaves/Needles
General Salicaceae Leaves/Needles
General Rosaceae Leaves/Needles
General Leguminosae See Comments
General Lichens Not Specified
General Bryophyta Not Specified
General Salicaceae Not Specified
General Caprifoliaceae Bole/Stem
General Caprifoliaceae Leaves/Needles
General Caprifoliaceae Fruit/Seeds
General Corn Not Specified
General Compositae Not Specified
General See Comments; Food See Comments
REFERENCES FOR GENERAL FOOD - 232
COMMENTS ON FOOD -
A study determined that selection of forage species by sheep is seasonal and
location-specific, indicating that caution should be used when
extrapolationg sheep food species from area to area. It concluded that
sheep select different forage plants on different ranges, partly on the
basis of their availability. Groups of plants, rather than individual plant
species, offer a more tenable means of categorizing the forage used by
sheep. These plant groups are: grass and sedge/leaves and stems; woody
stems and associated green leaves; leaves of willow (Salix spp.) and
mountain-avens (Dryas spp.); forb basal parts (mainly Oxytropis spp. in the
Alaska Range); and lichens and mosses *232*.
Winter:
Alaska Range: In the Alaska Range, Dall sheep prefer the leaves and seed
heads of grasses available above the snow (Calamagrostis spp., Festuca
spp., Agropyron spp., Poa spp.), sedges (Carex hepburnii), and lowbush
cranberry stems (Vaccinium vitis-idaea). Winter diet of sheep in
McKinley Park averaged 81.5% grasses and sedges *232*.
Kenai Maountains: Relatively few plant species comprise most of the
winter sheep diet on the Kenai Peninsula. Grasses (primarily Festuca
Food Habits - 1 (DRAFT) - Food Habits
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
altaica and F. rubra) and sedges (Carex spp.) were most commonly used,
with occasional use of crowberry (Empetrum nigrum), willow (Salix spp.)
and forbs (Erigeron spp., Dryas spp., false hellebore [Veratrum viride])
*232*.
Yukon Territory: Sage (Artemisia spp.) was an important winter food,
along with grasses and sedges *232*.
Spring: Sheep generally move to lower elevations in early spring (April) to
take advantage of vegetation exposed by the snowmelt. Overwintered
snow-cured grasses and sedges and cranberry leaves and berries are important
forage items at this time. As vegetation begins to grow again, grasses
(Festuca spp.) and sedges are initially sought, and mountain-avens, willow,
and Vaccinium spp. are utilized as soon as they leaf-out *232*.
Summer:
Alaska Range: Sheep during summer feed primarily on the most palatable
and nutritious plant parts, the leaves, bud, flowers, and herbaceous
stems. Relatively few plant species formed the major portion of the
summer diet. The most commonly used food species during summer in the
Alaska Range included Dryas octopetala; several grasses, notably Festuca
altaica and Hierochloe alpine; sedge (Carex microchaeta); willows (Salix
polaris pseudopolaris and S. reticulata); and forbs (Epilobium
latifolium, Oxyria digyna, and Geum rossii) *232*.
Kenai Mountains: Sedges were occasionally more abundant and made up a
larger portion of the summer diet than other commonly utilized grasses
(Hierochloe alplina and Festuca spp.) and willows *232*.
Types of Feeding Areas Used:
Winter: In early winter, sheep use lower-elevation slopes. These slopes
provide forage of good quality and quantity, even though they are
snow-covered. As winter progresses and snow becomes deeper and/or more
crusted by the wind, sheep move to exposed wind-blown, snowfree ridges.
In the Yukon Territory, 49% of all winter feeding occurred in areas of
no snow, 21% in areas with snow less than 5 cm (1.9 inches), and 17% in
areas with snow up to 10 cm (3.9 inches). About 9% of all feeding
occurred in areas with snow up to 15 cm (5.9 inches), 2.4% in snow depths
up to 20 cm (7.9 inches), and less than 1% in areas where snow depths
were between 20 and 30 cm (7.9 to 11.8 inches) *232*.
Spring: Sheep move to lower-elevation, snow-free southern slopes and
even into shrub tundra areas at the base of mountains to utilize early
plant growth. The winter-cured vegetation may have nutritional values
comparable to late-summer vegetation *232*.
Summer: Virtually all sheep range is available at this time; however, a
general trend is for the sheep to move gradually up-slope, following the
new plant growth, which is highly nutritious, mainly using southern
slopes but also other aspects. In late summer, feeding is extended to
northern slopes, where green plant growth occurs later *232*.
Food Habits - 2 (DRAFT) - Food Habits
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
Factors Limiting Availability of Food:
Winter: Sheep avoid areas where snow was over 18 inches deep and foraged
on wind-swept higher ridges for more readily available, less nutritious
food species. Snow hardness appears to be more important than snow
depth; however, both factors combine to limit digging activity by sheep.
Most digging for forage occurred in areas where snow was less than 1 ft
deep. Wind-blown snow develops a crust that is difficult for sheep to
paw through. Thaw-freeze conditions during winter can develop an ice
layer sometimes several inches thick, which sheep cannot paw through.
Unusually warm winters with heavy wet snow and/or rain can cause these
icing conditions, as happened in late winter 1969-1970 in the Kenai
Mountains and in December 1981 in the Alaska Range *232*.
Spring: Sheep utilize areas of early green-plant growth to maximize
their nutrient uptake *232*.
Feeding Behavior: Sheep are selective in their foraging pattern,
concentrating on what is most palatable, nutritious, and available to them
in the area *232*.
Winter: Pawing or cratering in snow by sheep allows access to forage
plants underneath. Sheep will feed in one crater, enlarge it, gaining
access to all forage plants, then move to another site and create another
crater. Smaller or less dominant animals are sometimes forced to move
from feeding craters by older or larger sheep. Feeding craters on the
Kenai were dug in snow up to 10 inches deep. A study found sheep had
pawed through snow up to 14 inches deep. Sheep show a patern of limited
energy expenditure during winter, with less feeding activity in the
morning and more in the warmer afternoon periods *232*.
Spring/Summer: During spring and summer sheep selected high-quality, new
growth vegetation and chose the most nutritious species within mixed
stands *232*.
Mineral Licks: A study recommended that mineral licks be considered
critical habitat areas for Dall sheep populations in interior Alaska. All
segments of the study population utilized the licks with a high degree of
fidelity, that there was preferential use by lactating ewes, and that sheep
travel significant distances (12+ mi), sometimes out of their way, to visit
licks. Mineral licks provide physiologically important ions for sheep,
including calcium, magnesium, sodium, and potassium *232*.
Interior: Alaska Range-Dry Creek: Seasonal use of this lick occurs from
mid May through early July, with the peak of use varying but usually
occurring from the first to the third week of June. Ewe fidelity, or
annual return to the lick, was 100%; ram fidelity was 80%. Rams begin
use in mid May-early June, followed by juveniles and then ewes and lambs
in late June-early July. Rams and ewes without lambs spent an average of
four days at the lick. Ewes with lambs spent an average of six and
one-half to seven days *232*.
Food Habits - 3 (DRAFT) - Food Habits
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
Southcentral: Watana Hills-Jay Creek: Seasonal use of this lick occurs
from early May through at least mid August, with peak use occurring from
mid May through June. Rams begin lick use in early May, followed by
ewe-yearling groups in late May and ewes and lambs in mid June. Another
mineral lick located near the east fork of Watana Creek was also utilized
seasonally by Watana Hills sheep *232*.
Arctic: Brooks Range-Hulahula River: Seasonal lick use occurs from
April through October and perhaps all year, with peak use occurring in
June. Rams utilized the lick primarily before 26 June, with ewes, lambs,
and yearlings increasing after that *232*.
Food Habits - 4 (DRAFT) - Environment Associations
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Elevation: 500-1000 ft.
G Elevation: Specified in Comments
G Slope: Specified in Comments
G Terrestrial Features: Cliffs/ledges
G Terrestrial Features: Specified in Comments
G Terrestrial Features: Caves, dry
BA Terrestrial Features: Cliffs/ledges
BA Terrestrial Features: Specified in Comments
G Elevation: Specified in Comments
FA Slope: Specified in Comments
BA Slope: Specified in Comments
BA Aspect: South
BA Aspect: Specified in Comments
G Aspect: South
G Aspect: Specified in Comments
FA Aspect: South
FA Aspect: Specified in Comments
FA Terrestrial Features: Cliffs/ledges
FA Terrestrial Features: Specified in Comments
FA Elevation: Specified in Comments
FA Aspect: North
G Aspect: North
G Aspect: Specified in Comments
G Elevation: 2000-3000 ft.
G Elevation: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR FEEDING ADULT ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 232
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Sheep are capable of using all suitable habitat in the mountain ranges they
occupy. On a seasonal basis, there is generally little difference in the
physical habitat parameters that sheep prefer. Typically, precipitous
terrain with rocky slopes, ridges, and cliffs is used; this habitat
preference is most likely related to predator avoidance *232*.
Environment Associations - 1 (DRAFT) - Environment Associations
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
Winter: In winter, sheep utilize windward southern exposures where
available, which provide areas of shallow snow and maximum solar radiation
for warmth. In some locations, however, sheep utilize other exposures
where the wind exposes forage on ridges. They will sometimes move from
exposed sloped to protected cliff areas prior to storms and occasionally
gather together in cliff crevices or caves for warmth and to avoid strong
winds *232*.
Spring/lambing: The spring range of Dall sheep is in general similar to
their winter range, except that they move to lower elevations and more
southerly exposures when possible. Near Cooper Landing and at Indian,
south of Anchorage, for example, sheep are known to use the low-elevation,
south-facing slopes in the spring. South-facing cliffs and slopes are
apparently very important in spring, affording maximum solar radiation for
warmth and faster snowmelt. Preferred lambing areas are on the most
precipitous, inaccessible cliffs available *232*.
Summer: Dall sheep habitat requirements during summer are essentially the
same as at other periods, although they may tend to utilize shady areas and
ridge tops more frequently to obtain relief from insect harassment *232*.
Dall sheep are distributed throughout suitable alpine habitat, generally
above 2,500 ft, in major mountain ranges of Alaska. Researchers observed
sheep at elevations as low as 700 ft. Habitat in the Alaska Range consists
of almost continuous alpine areas on the northern slope. Sheep habitat on
the south slope of the Alaska Range is discontinuous, with severe winter
weather conditions limiting sheep distribution to a large extent *232*.
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
Types of Feeding Areas Used:
Winter: In early winter, sheep use lower-elevation slopes. These slopes
provide forage of good quality and quantity, even though they are
snow-covered. As winter progresses and snow becomes deeper and/or more
crusted by the wind, sheep move to exposed wind-blown, snowfree ridges.
In the Yukon Territory, 49% of all winter feeding occurred in areas of
no snow, 21% in areas with snow less than 5 cm (1.9 inches), and 17% in
areas with snow up to 10 cm (3.9 inches). About 9% of all feeding
occurred in areas with snow up to 15 cm (5.9 inches), 2.4% in snow depths
up to 20 cm (7.9 inches), and less than 1% in areas where snow depths
were between 20 and 30 cm (7.9 to 11.8 inches) *232*.
Spring: Sheep move to lower-elevation, snow-free southern slopes and
even into shrub tundra areas at the base of mountains to utilize early
plant growth. The winter-cured vegetation may have nutritional values
comparable to late-summer vegetation *232*.
Summer: Virtually all sheep range is available at this time; however, a
general trend is for the sheep to move gradually up-slope, following the
new plant growth, which is highly nutritious, mainly using southern
slopes but also other aspects. In late summer, feeding is extended to
northern slopes, where green plant growth occurs later *232*.
Environment Associations - 2 (DRAFT) - Environment Associations
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Spring/lambing: The spring range of Dall sheep is in general similar to
their winter range, except that they move to lower elevations and more
southerly exposures when possible. Near Cooper Landing and at Indian,
south of Anchorage, for example, sheep are known to use the low-elevation,
south-facing slopes in the spring. South-facing cliffs and slopes are
apparently very important in spring, affording maximum solar radiation for
warmth and faster snowmelt. Preferred lambing areas are on the most
precipitous, inaccessible cliffs available *232*.
Reproductive Habitat: Breeding occurs on the winter range in high cliff
terrain or on broken, steep slopes. Occasional breeding takes place away
from normal breeding areas, usually following a ram/ewe chase. Lambing
occurs on portions of the winter range, in areas of steep, broken,
precipitous terrain. Areas where protection from wind and other weather
factors is available are favored *232*.
Environment Associations - 3 (DRAFT) - Life History
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
LIFE HISTORY
REPRODUCTIVE CHARACTERISTICS
Reproductive Habitat: Breeding occurs on the winter range in high cliff
terrain or on broken, steep slopes. Occasional breeding takes place away
from normal breeding areas, usually following a ram/ewe chase. Lambing
occurs on portions of the winter range, in areas of steep, broken,
precipitous terrain. Areas where protection from wind and other weather
factors is available are favored *232*.
Breeding Seasonality: The peak of breeding activity extends approximately
from mid November through mid December. The lambing period extends from
late May through mid June. The estimated peak date of lambing on the Kenai
Peninsula was 24 May *232*.
Breeding Behavior: Breeding is polygamous and is conducted mostly by ewes
with dominant rams. Dominance among rams is determined in September and
October by a complicated display ritual and occasional combat. The physical
effort expended by dominant rams during breeding depletes their energy
reserves, leaving them in poor physical condition. A severe winter will
probably result in high mortality among these individuals *232*.
Age at Sexual Maturity: Rams are sexually mature at 18 to 30 months;
however, dominiance order usually prevents breeding until rams are six to
eight years old. Ewes are sexually mature at 18 months *232*.
Fecundity: Single births are usual, although twinning has very rarely been
reported and never documented. The gestation period is approximately 171
days *232*.
Frequency of Breeding: Ewes can produce one lamb a year. Under some
conditions ewes produce only one lamb every other year *232*.
FACTORS INFLUENCING POULATIONS
Natural: Deep snow and severe icing conditions appear to be major factors in
limiting sheep populations in maritime areas. Wolves are a major predator in
areas where the wolf population is high and/or escape terrain is limited.
Predation by bears, coyotes, lynx, and other predators occurs, but the
extent is unknown. Golden eagles are thought to be serious predators of
lambs during their first few weeks of life. Major diseases and parasites
associated with Dall sheep in Alaska include contagious ecthyma,
lungworm-pneumonia complex, mandibular osteomylitis (lumpy jaw), and several
species of gastro-intestinal helminth worms *232*.
Human-related: The most serious human-related threat to Dall sheep in
Alaska comes in the form of introduced diseases from domestic sheep. Wild
animal populations seldom have the defenses necessary to withstand
introduced diseases. These introductions were responsible for most of the
decimation of wild sheep populations in the western United States. Other
human-related factors influencing sheep populations are the following:
competition with introduced (wild or domestic) animals; harassment, active;
Life History - 1 (DRAFT) - Life History
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
harassment, passive, construction noise, aircraft traffic; hunting;
vegetation damage/destruction due to grazing by domestic animals *232*.
LIFE HISTORY CODES -
Breeding/Spawning Season: November
Breeding/Spawning Season: December
Breeding/Spawning Season: May
Breeding/Spawning Season: June
Mating System (Single breeding season): Polygamy (mal
Average Number of Offspring/Reproductive Effort: 1
Average Number of Offspring/Reproductive Effort: 2
Gestation/Incubation Period: 5-6 months
Number of Broods/Litters (Reproductive Efforts) Per Ye
REFERENCES FOR LIFE HISTORY- 232
Life History - 2 (DRAFT) - Management Practices
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Controlling undesirable vertebrate species
Beneficial Regulating harvest of species being described
Beneficial Prohibiting harvest of species being described
Beneficial Restricting/regulating human disturbance of populations
Beneficial Controlling grazing of domestic livestock
Beneficial Other management practices [specified in comments]
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 232
COMMENTS ON MANAGEMENT PRACTICES -
The most serious human-related threat to Dall sheep in Alaska comes in the
form of introduced diseases from domestic sheep. Wild animal populations
seldom have the defenses necessary to withstand introduced diseases. These
introductions were responsible for most of the decimation of wild sheep
populations in the western United States. Other human-related factors
influencing sheep populations are the following: competition with introduced
(wild or domestic) animals; harassment, active; harassment, passive,
construction noise, aircraft traffic; hunting; vegetation damage/destruction
due to grazing by domestic animals *232*.
Management Practices - 1 (DRAFT) - References
Species sheep, Dall
Species Id M050055
Date 26 AUG 96
References
232 * State of Alaska Department of Fish, and Game. 1986. Alaska
Habitat Management Guide: Life Histories and Habitat
Requirements of Fish and Wildlife. (ed.). Alaska Department of
Fish and Game Juneau, Alaska:763.
References - 1