Alces americanus (Clinton, 1822)
Basis for Listing
The range of Moose (Alces americanus) in North America stretches from Alaska across Canada and into New England, south through the Rocky Mountains to Colorado, North Dakota, northern Minnesota, and the Upper Peninsula of Michigan (Franzmann 1981). Prior to European settlement, Moose were distributed throughout northern Minnesota. By the early 1970s, hunting, habitat loss, and alteration had restricted the species' to two disjunct populations in the northeastern (Northern Superior Uplands Section) and northwestern (Aspen Parklands Subsection) portions of the state. Each of these populations numbered in the thousands into the mid-1980s.
The primary factors limiting the geographic distribution of Moose at the southern limit of its range are climate and, most importantly, temperature (Renecker and Hudson 1986). Northern Minnesota is at the southern edge of the North American Moose range at this latitude. From the mid-1980s until the early 2000s, Minnesota witnessed a collapse of the northwestern moose population. During this time, population numbers fell from as many as 4,000 to less than 100 (Lenarz 2007). Murray et al. (2006) concluded that climate change, acting in tandem with pathogens and malnutrition, was responsible for this decline. Similarly, a decline of approximately 50% has occurred in Minnesota’s northeastern moose population since 2005 (Lenarz et al. 2010; DelGiudice 2016). This decline prompted the designation of the Moose as a species of special concern in 2013.
The Moose is the largest of the North American deer species, standing 1.5 -2.1 m (4.9-7.0 ft.) at the shoulder and weighing 360-710 kg (794-1565 lbs.) or more (Franzmann et al. 1987). Adult male Moose (bulls) are heavier than females (cows), upwards of 40% heavier (Feldhamer et al. 2003). Coloration is age, social rank, sex, and seasonally dependent. Coat coloration can range from a yellowish brown to almost black (Mitchell 1970). Moose have the largest antlers of any living cervid in North America (Feldhamer et al. 2003). Antlers are generally palmate with well-expressed brow tines. Antler spreads rarely exceed 1.7 m (5.6 ft.) ( Timmermann 1971). Bulls do not have fully developed antlers until five years of age (Schwartz et al. 2007). Long legs allow Moose to easily travel through deep snow, evade predators, and conserve energy. Body mass is both gender and seasonally dependent. Bulls reach peak mass just before the rut in the fall (late September through mid-October), losing 7-23% of pre-rut mass overwinter. Cows reach maximum body mass in early winter, followed by losses of 15-19% during the winter, reaching yearly lows just before calving in the spring (mid-May through June; Schwartz et al. 2007).
Boreal forest is the primary habitat for Moose. This forest type is dominated by spruce (Picea spp.), fir (Abies spp.), and pine (Pinus spp.). Boreal forest is often interspersed with vast wetlands characterized by bogs and fens. The southern limit of boreal forest is found in the contiguous United States, including northern Minnesota. Boreal forest in northeastern Minnesota is patchy and interspersed with other habitats, such as acid peatlands and northern hardwood forest. Principal deciduous species in this intermixed landscape include birch (Betula spp.), aspen (Populus spp.), and willow (Salix spp.). Areas of early-successional habitat created by timber harvest, forest fires, and windstorms are preferred in northeastern Minnesota (Peek et al. 1976).
In northwestern Minnesota, Moose occur in the transitional zone between fire-dependent boreal forest and temperate prairie. This mixed transitional forest is characterized by large areas of wetlands and shrublands intermixed with stands of confers and hardwoods (Schwartz et al. 2007).
Biology / Life History
Moose are considered the least social of North American cervids, but they are not considered territorial and often share home ranges. Conspecific (within species) aggression varies depending on season, age, and gender. Cows are usually more solitary than bulls throughout the year (Schwartz et al. 2007). Minnesota Moose are mostly non-migratory, except for seasonal movements between winter and summer ranges. Annual home range sizes are larger for bull Moose (58 km² [22 sq. mi.]) than cows (30 km² [12 sq. mi.]); Lenarz et al. 2011). Cows tend to select habitats with more cover, possibly as a predation avoidance strategy, especially when with calves. Groups of Moose are most common during rut (the breeding season; Schwartz et al. 2007). Moose are polygamous, with the rut peaking during late September to mid-October. The rut falls within the primary estrous period, with estimates of up to 89% of cows conceiving during this period (Edwards and Ritcey 1958). Pregnancy rates have ranged from 77-89% for moose in Minnesota in recent years (Carstensen et al. 2014). Gestation ranges from 216 to 246 days with most calving occurring from mid-May to mid-June (Schwartz et al. 2007). Moose typically have single or twin calves, with triplets being rare. Calves are weaned during the following rut and will remain with their mother until the following spring. They are often driven away several weeks before parturition (Schwartz et al. 2007).
Moose have distinct summer and winter coats, with shedding occurring in the spring and fall. Their large body and dense coats make them susceptible to heat stress (Feldhamer et al. 2003). Renecker and Hudson (1986) found that temperatures greater than 5°C (41°F) in the winter and 14-20°C (57-68°F) in the warm season (late spring to early fall) are associated with symptoms of heat stress. McCann et al. (2013) found similar thresholds for late spring to early fall (17-24°C [63-75°F]). Moose seldom live longer than 16 years, though some cows have been reported living past 20 years of age. Females often live longer than males. Natural predators in Minnesota include Gray Wolves (Canis lupus) on calves and adults and Black Bears (Ursus americanus) on calves. Other forms of mortality include natural accidents, automobile and train collisions, poaching, and a number of health related causes. Health related issues include bacterial infections, winter ticks, liver flukes (Fascioloides magna), and brainworm (Parelaphostrongylus tenuis) amongst others (Carstensen et al. 2014).
Conservation / Management
In Minnesota, the large majority of habitat management for Moose is achieved through the use of commercial timber harvest. The Minnesota Moose Advisory Committee recommended that management focus on increasing stand complexity, promoting shrub production, maintaining thermal cover, and protecting aquatic foraging areas. Harvest techniques should be used to mimic natural disturbance patterns such as fire, wind, and insect and disease outbreaks. Prescribed fire should be used where appropriate to improve the quantity and quality of moose browse available as well as possibly reducing winter ticks and gastropods.
Conservation Efforts in Minnesota
Historically, Moose have been hunted in Minnesota. However, due to the accelerated population decline of the northeastern population over the past 10 years, the DNR suspended all moose hunting in 2013. That same year, the DNR started one of the largest and most high-tech multi-partner moose research projects in North America. This multi-year research project seeks to understand the causes of adult moose mortality, calf mortality, calf survival, and habitat use. To date, 173 adult Moose have been captured and deployed with GPS collars. Preliminary results have given researchers new insight as to why the Minnesota moose population is declining, including the climate and health related issues facing Moose inthe state. The information gained from this study may help identify management options that can slow or stop the moose population decline in Minnesota. Currently, annual aerial surveys in northeastern Minnesota are being conducted to monitor the moose population.
Andrew Herberg (MNDNR), 2018
(Note: all content ©MNDNR)
References and Additional Information
Carstensen, M., E. C. Hildebrand, D. C. Pauly, R. G. Wright, and M. H. Dexter. 2014. Determining cause-specific mortality in Minnesota's northeast moose populations. Pages 142-152 in L. Cornicelli, M. Carstensen, M. D. Grund, M. A. Larson, and J. S. Lawrence, editors. Summaries of wildlife research findings, 2013. Minnesota Department of Natural Resources, Wildlife Populations and Research Unit, St. Paul. 205 pp.
DelGiudice, G. D. 2016. 2016 Aerial moose survey. Forest Wildlife Populations and Research Group, Minnesota Department of Natural Resources, St. Paul. 7 pp.
Edwards, R. Y., and R. W. Ritcey. 1958. Reproduction in a moose population. Journal of Wildlife Management. 22(3):261-268.
Feldhamer, G. A., B. C. Thompson, and J. A. Chapman, editors. 2003. Wild mammals of North America: biology, management, and conservation. Second edition. Johns Hopkins University Press, Baltimore, Maryland. 1232 pp.
Franzmann, A. W. 1981. Alces alces. Mammalian Species. 154:1-7.
Franzmann, A. W., and C. C. Schwartz, editors. 2007. Ecology and management of the North American Moose. Second edition. University Press of Colorado, Boulder. 776 pp.
Franzmann, A. W., C. C. Schwartz, and D. C. Johnson. 1987. Evaluation and testing of techniques for moose management. Federal Aid in Wildlife Restoration Research Final Report. Alaska Department of Fish and Game, Juneau. 20 pp.
Hazard, E. B. 1982. The mammals of Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 280 pp.
Lenarz, M. S. 2007. 2007 Minnesota Moose harvest. Forest Wildlife Populations and Research Group, Minnesota Department of Natural Resources, St. Paul. 4 pp.
Lenarz, M. S. 2012. 2012 Aerial moose survey. Forest Wildlife Populations and Research Group, Minnesota Department of Natural Resources, St. Paul. 6 pp.
Lenarz, M. S., J. Fieberg, M. W. Schrage, and A. J. Edwards. 2010. Living on the edge: viability of moose in northeastern Minnesota. Journal of Wildlife Management 74(5):1013-1023.
Lenarz, M. S., M. E. Nelson, M. W. Schrage, and A. J. Edwards. 2009. Temperature mediated Moose survival in northeastern Minnesota. Journal of Wildlife Management 73(4):503-510.
Lenarz, M. S., M. W. Schrage, A. J. Edwards, and M. Nelson. 2008. Moose population dynamics in northeastern Minnesota. Pages 66-69 in M. W. DonCarlos, R. O Kimmel, J. S. Lawrence, and M. S. Lenarz, editors. Summaries of wildlife research findings, 2008. Wildlife Populations and Research Unit, Minnesota Department of Natural Resources, St. Paul. 227 pp.
Lenarz, M. S., R. G. Wright, M. W. Schrage, and A. J. Edwards. 2011. Compositional analysis of moose habitat in northeastern Minnesota. Alces 47:135-149.
McCann, N. P., R. A. Moen, and T. R. Harris. 2013. Warm-season heat stress in Moose (Alces alces). Canadian Journal of Zoology 91(12):893-898.
McGraw, A. M., R. Moen, G. Wilson, A. Edwards, R. Peterson, L. Cornicelli, M. Schrage, L. Frelich, M. Lenarz, and D. Becker. 2010. An advisory committee process to plan Moose management in Minnesota. Alces 46:189-200.
Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.
Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the prairie parkland and tallgrass aspen parklands provinces. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 362 pp.
Mitchell, H. B. 1970. Rapid aerial sexing of antlerless moose in British Columbia. Journal of Wildlife Management 34:645-646.
Murray, D. L., E. W. Cox, W. B. Ballard, H. A. Whitlaw, M. S. Lenarz, T. W. Custer, T. Barnett, and T. K Fuller. 2006. Pathogens, nutritional deficiency, and climate influences on a declining moose population. Wildlife Monographs 166(1):1-30.
Peek, J. M., D. L. Urich, and R. J. Mackie. 1976. Moose habitat selection and relationships to forest management in northeastern Minnesota. Wildlife Monographs No. 48.
Peterson, R. O. 1999. Moose (Alces alces). Pages 334-336 in D. E. Wilson and S. Ruff, editors. The Smithsonian book of North American mammals. Smithsonian Institution Press in association with the American Society of Mammalogists, Washington, D.C. 816 pp.
Renecker, L. A., and R. J. Hudson. 1986. Seasonal energy expenditures and thermoregulatory responses of moose. Canadian Journal of Zoology, 64(2):322-327.