Oreamnos americanus

Geographic Range

The native range of this species is from southeast Alaska to Washington, western Montana, and central Idaho. Mountain goats, Oreamnos americanus , are native to the northern Rocky Mountains. They have also been introduced to parts of South Dakota, Colorado, and Washington.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native

Habitat

Mountain goats prefer steep, rocky areas with cliffs or bluffs in alpine or sub-alpine regions. They prefer areas with sufficient escape terrain (steep rocky areas), moderate slopes, mid-elevations, and southern exposures. They migrate between lowland winter areas and high elevation summer ranges.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• mountains mountains

Physical Description

Mountain goats are stout-bodied with a thick coat made up of white hairs with some brown intermixed dorsally. The pure black horns are about 200 to 300 mm long, rather thin, and present on both sexes. They do not shed these horns--annual growth rings increase the horn size. In this way, the age of the goat can be determined by counting the number of annual growth rings. The male's horn, however, curves back greater than the females. Mountain goats have relatively large, oval hooves with an almost rubber-like sole that aids them in climbing steep rock. They have black scent glands between their horns. The body size of a male and female are similar until 3 years of age. After 3 years of age males are usually 7.5 to 15 cm taller than females. Male mountain goats usually weigh between 61.4 to 81.8 kg and females 56.8 to 70.5 kg.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes shaped differently
• ornamentation ornamentation

Reproduction

Prior to and during the breeding season, males compete for females. The do not fight head-to-head but rather stand side-by-side and stab at each other's flanks. Thick skin in this area protects them from serious damage, but deaths have been reported and are usually associated with wounds to the chest, neck, or abdomen.

Courtship begins in September when males attempt to join small bands of females (alone or in pairs). Males tend to be easier to distinguish at this point, as their coats are dirtier--caused by the action of digging a rutting pit. Male courtship behavior involves a low approach to the female, showing the broad side of the face and beard, licking the female's coat, and kicking the female's flanks. In late October, the females finally accept the courtship of males; these males become part of a "nursery band." These include a female, her young, and any males who have joined in the pre-rut season. Males will typically attempt to prevent other males from copulating with any female (including non-estrous females) when in the nursery band.

• Mating System
• polygynous polygynous

Mountain goat breeding season begins in late November and lasts until early January. Gestation is about 150 to 180 days and 1 to 3 kids are born in May to June. The female gives birth on very steep cliffs in her home range to avoid predators. The young are mobile shortly after birth. The young are weaned after 3 to 4 months and stay with the mother until she gives birth the following year. Sexual maturity is reached after 30 months in both sexes, although Cote and Festa-Bianchet (2001) found that kid production was highest among female goats at 8 to 9 years of age. These authors also found that age and social rank were positively correlated, so older females of a higher social rank tend to produce more offspring than lower-ranked, younger females.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Kids stay with their mother until weaned, from 90 to 120 days old. Following weaning, kids typically stay with the mother until another is born, at which point the mother chases away the yearling. Males aid in the protection of young when they are a part of a nursery band; otherwise the mother is the main source of protection.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female
• post-independence association with parents

Lifespan/Longevity

Mountain goats typically live until their teeth have been worn completely down--on average, 12 to 15 years in the wild and 16 to 20 years in captivity. This age can be determined by the number of annual growth rings on the interior of the horns. Most goats, however, do not survive more than 12 years. The oldest reported male and female were 15.5 and 18 years old, respectively.

Behavior

The degree of sociality of mountain goats varies throughout the year. They tend to form large groups during the winter and concentrate at salt licks in the spring, but they form smaller groups or are solitary in the summer. They are active from sunrise to mid-day and again at dusk. Mountain goats establish dominance hierarchies at a young age, by means of the kids' playing behavior. Males are dominant during the breeding season, but non-breeding season hierarchy is unusual. At this time, adult females are dominant, while adult males are subordinate to females and juveniles.

Mountain goats dig 25 - 50 mm deep "bedding depressions," where they rest during the mid-day and night. They also dust bathe in these depressions, possibly to remove parasites or shedding skin/hair. These beds have caused damage to certain rare and endangered plant populations in areas of Washington where mountain goats have been introduced.

• Key Behaviors
• terricolous
• diurnal diurnal
• motile motile
• migratory migratory
• social social
• dominance hierarchies dominance hierarchies

Home Range

Home ranges are approximately 23 square km in the summer and much smaller in the winter. Mountain goats typically migrate latitudinally, so absolute distance between summer and winter home ranges is rather small. A study by Poole and Heard noted that some radio-collared goats used winter and summer ranges that were 8 to 13 km apart (coupled with less elevational change).

Communication and Perception

Mountain goats communicate through vocalitizations during the mating season to attract mates. They display a high frequency of intraspecific aggression. Aggressive behaviors include present threat (a broadside orientation with apparent size enhancement by arching their backs), horn threat (aggressive movement and display of the horns), rush threat (a sudden quick movement toward the antagonist), and orientation threat (a lower intensity form of rush threat involving walking). All of these are examples of bluffing aggression, as individuals rarely suffer serious injuries.

• Communication Channels
• visual visual
• tactile tactile

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Although their diet varies throughout the year, it generally consists of grasses, woody plants, mosses, lichens, herbaceous plants, and other vegetation. They get most of their water from their food and year-round snowbanks. Mountain goats also travel many kilometers in the spring to mineral-rich salt licks.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • lignivore

• Plant Foods
• leaves
• wood, bark, or stems
• bryophytes
• lichens

Predation

The mountain goat's main predators are cougars ( Puma concolor ). The cougar is versatile enough to move around on the mountains and it is big enough to hunt and kill an adult mountain goat. Bears ( Ursus species) may rarely catch a goat when they are on the ground, but if the goats stay on the mountain, it would be extremely difficult for the bear to catch it. Eagles occasionally swoop down and carry off newborns. Wolves ( Canis lupus ) have been known to also attack mountain goats. In July and August of 1995, one wolf killed a yearling female. However, soon after that incident a adult female successfully defended her kid from an adult wolf. This aggressive defense is rare--a study in 2006 noted just 5 occasions in which mothers defended their kids.

Ecosystem Roles

Ectoparasites that have been found on mountain goats are Dermacentor andersoni (a tick), and a chewing louse, Bovicola oreamnidis . Endoparasites that have been known to affect mountain goats are three species of cestodes: Moniezia benedeni , Thysanosoma actinioides , and Taenia hydatigena . Also 11 species of nematodes: Protostrongylus stilesi , Protostrongylus rushi (both were found on the lungs), Ostertagia circumcincta , O. ostertagi , O. trifurcata , Trichostrongylus colubriformis , Trichostrongylus axei , Nematodirus maculosus and N. helvetianus (the latter 2 found in the small intestines). Also tapeworms seem to be an endoparasite that have affected goats in South Dakota.

• Ecosystem Impact
• keystone species keystone species

Economic Importance for Humans: Positive

Mountain goat hunting is very challenging due to the habitat the goats inhabit.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

It has been reported that in places of high mountain goat populations, they cause destruction to plant populations native to that region. This has become a big concern at Olympic and Yellowstone National Parks. Mountain goats are not native to those areas, and are considered an exotic species there. Like other exotic species there is concern about mountain goats bringing in new diseases that will infect native organisms from these areas.

• Negative Impacts
• injures humans
  • causes disease in humans causes disease in humans

Conservation Status

Because the number of mountain goats has been relatively stable, they are not in any danger of extinction. Some areas, like Yellowstone National Park, have allowed hunters to hunt under controlled conditions to reduce the number of mountain goats. Hunting is not allowed in any places where mountain goats are declining in number, like Cascade Mountains of Washington. Goats in this region are being tagged with GPS collars to track their progress, and find out why their numbers are slowly declining.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Julie Fitch (author), Radford University, Brandi Guilliams (author), Radford University, Whitney Mowbray (author), Radford University, Allen Patton (author), Radford University, Sean Gloss (author), Radford University, Karen Powers (editor, instructor), Radford University.

Eric J. Ellis (author), University of Michigan-Ann Arbor.

References

Asdell, S. 1964. Patterns of Mammalian Reproduction (2nd ed.) . Ithaca, NY: Cornell University Associates.

Boddicker, M., E. Hugghins, A. Richardson. 1971. Parasites and Pesticide Residues of Mountain Goats in South Dakota. Journal of Wildlife Management , 35: 94-103.

Cote, S., A. Peracino, G. Simard. 1997. Wolf, Canis lupus, predation and maternal defensive behavior in mountain goats, Oreamnos americanus. Canadian Field-Naturalist , 11: 389-392.

Cote, S., M. Festa-Bianchet. 2001. Reproductive Succes in Female Mountain GOats: the Influence of Age and Social Rank. Animal Behavior , Vol. 62, No. 1: 173-181.

Geist, V. 1964. On the Rutting Behavior of the Mountain Goat. Journal of Mammalogy , Vol. 45, No. 4: 551-568.

Gross, J., M. Kneeland, D. Reed, R. Reich. 2002. Gis-Based Habitat Models for Mountain Goats. Journal of Mammalogy , 83(1): 218-228.

Lemke, T. 2004. Origin, expansion, and status of mountain goats in Yellowstone National Park. Wildlife Society Bulletin , 32/2: 532-541.

Lyman, R. 1994. The Olympic Mountain Goat Controversy: A Different Perspective. Conservation Biology , 8: 898-901.

Nowak, R. 1991. Walker's Mammals of the World, 5th Ed. . Baltimore, MD: The Johns Hopkins University Press, pp. 1475-1476..

Poole, K., D. Heard. 2003. Seasonal Habitat Use and Movements of Mountain Goats, Oreamnos americanus, in East-central British Columbia. Canadian Field-Naturalist , 117/4: 565-576.

Rice, C. 2003. "Mountain Goat Research in the Washington Cascade Mountains" (On-line pdf). Accessed August 28, 2007 at http://wdfw.wa.gov/science/articles/mtn_goats/mtn_goat_prog_rpt.pdf .

Rideout, C., R. Hoffmann. 1975. Oreamnos americanus. Mammalian Species , 63: 1-6.

Smith, C. 1986. Rates and causes of mortality in mountain goats in southeast Alaska. Journal of Wildlife Management , 50: 743-746.

Trivedi, A. 2007. "Benedictine University" (On-line). Accessed August 28, 2007 at http://www.ben.edu/museum/mountain_goat.asp .

Wilson, D., R. Kays. 2002. Mammals of North America . Princeton: Princeton University Press.

MacDonald, Dr. David. 1984. The Encyclopedia of Mammals. Equinox (Oxford), Ltd. Pgs. 584-588.

Parker, Sybil P [Editor]. 1990. Grzimek's Encyclopedia of Mammals, Vol 5. McGraw-Hill Publishing. Pgs 501-505.

mt.gov. 2007. "Mountain Goats" (On-line). Montana's Official State Website. Accessed August 24, 2007 at http://fwp.mt.gov/wildthings/brochure_goat.html#body .

Department of Agriculture. Oreamnos americanus. Rocky Mountain Research Station, Fire Sciences Labratory: Julie L. Tesky. 1993. Accessed August 28, 2007 at http://www.fs.fed.us/database/feis/animals/mammal/oram/all.html .