Bison vs Moose: Size, Weight, and Range Compared

Headline numbers

The largest-land-mammal-in-North-America question

The single most asked question about these two animals is which is the larger. The answer depends on what dimension matters. By mass, the bison wins. By shoulder height, the moose wins. Both claims are correct simultaneously.

Adult bull American bison routinely reach 900 to 1,000 kilograms. Exceptional bulls in commercial herds and well-fed conservation populations regularly pass 1,100 kg. The wood bison subspecies (Bison bison athabascae) is the heaviest, with bulls reaching the upper end of this range and occasional records past 1,200 kg. The heaviest American bison ever recorded in modern times was a wood bison bull at approximately 1,270 kg.

Adult bull moose, depending on subspecies, weigh 600 to 750 kg across most of the range. The Alaska-Yukon moose (Alces alces gigas) is the largest subspecies and bulls in this population can reach 700 to 800 kg, with the heaviest documented Alaska-Yukon bull at approximately 825 kg. The eastern and western moose subspecies of the lower 48 states and southern Canada are smaller, typically 550 to 650 kg for bulls. Even the largest moose subspecies falls below the average weight of an American bison.

By shoulder height the answer flips. Bull moose stand 1.8 to 2.1 metres at the shoulder in healthy populations, with Alaska-Yukon bulls regularly above 2.0 m. Bull bison stand 1.6 to 1.85 metres, with the very tallest plains bulls at the bottom of the moose range. The moose is the taller animal by 15 to 25 cm at the shoulder, and the moose head adds another full metre above the shoulder line. A bull moose's antler spread can add another metre of horizontal reach. Standing next to a moose, an adult human looks small in a way that they do not next to a bison.

Horns vs antlers: a permanent vs annual structure

The bison carries horns. The moose carries antlers. The two structures look superficially similar but are fundamentally different growths.

Horns are permanent. They consist of a bony core that grows from the skull, covered by a sheath of keratin (the same material as hair and fingernails). Horns are present on both sexes in the bison and grow continuously throughout the animal's life, slowly expanding in length and basal circumference. A 15-year-old bull bison's horns are larger than a five-year-old's, and an injured horn does not regenerate. Both sexes of bison have horns and use them for defence and dominance.

Antlers are temporary. They are pure bone, not keratin-sheathed, and grow from a pedicel on the skull each year, are shed in late winter, and regrow each spring. Only bulls carry antlers. The growing antler is covered in a soft skin called velvet, which carries blood vessels supplying the rapidly forming bone; velvet is shed in late summer as the antler hardens for the rut. A bull moose's antler set takes three to five months to grow and can reach 1.8 metres in span and 30 kg in weight. The set is then carried for a few months and shed in December or January. The bull is antler-less through the back end of winter and into early spring.

Diet: grazer vs browser, no competition

Bison and moose do not compete for the same forage. The bison is a grass grazer and gets roughly 90 per cent of its diet from grasses and sedges, with the balance from forbs and a small fraction of browse. The moose is a pure browser; grass is functionally absent from the diet. Moose eat the leaves and twigs of willow, aspen, birch, and dogwood, and in summer they eat large quantities of aquatic plants, particularly water-lily roots, pondweeds, and the submerged stems of rushes and sedges. Aquatic feeding is a signature moose behaviour and one of the easier ways to spot the species, often standing shoulder-deep in a lake or beaver pond with the head fully submerged.

Because the two species use different plant resources, they can occupy overlapping habitat without ecological conflict. In Yellowstone, plains bison and moose both range through willow-rich riverbottoms in late summer; the bison eats the riverbottom grass and the moose eats the willow leaves. In the boreal forests of northwestern Canada, wood bison and moose share large areas of fen and riparian habitat with the same partitioning.

Range and population

Moose range across the entire boreal forest of North America from Alaska through the Yukon, the Northwest Territories, the prairie provinces, northern Ontario, Quebec, the Maritimes, into New England, the Great Lakes states, and through the Rocky Mountains south to Colorado and northern Utah. The total North American moose population is approximately one million animals, more than double the total bison population. Moose also range across the boreal forests of Eurasia, where the species is called elk in Europe (confusingly, because the same word in North America means a different deer species, Cervus canadensis).

Bison are restricted to North America and to a much smaller modern range. The wild conservation herd is estimated at roughly 31,000 animals across 60-plus protected populations, with the commercial herd of approximately 470,000 spread across ranches in the United States and Canada. The total population is about 500,000, half the moose count. Wood bison occupy the boreal forest of northern Alberta, British Columbia, the Northwest Territories, and Yukon, where they overlap with moose. Plains bison occupy grassland reserves and parks farther south.

Behaviour and the rut

Bison are highly social. Cow-calf groups of 20 to 50 animals are the basic social unit, and during summer these groups aggregate into much larger herds of hundreds or (historically) thousands. Bulls live separately in small bachelor groups outside of the rut and rejoin the cow herds in July through September, where dominance is established through bellowing contests, wallowing displays, and shoving and horn-locking fights.

Moose are largely solitary. Cows live with their calves of the year and the previous year, but bulls and cows live separately outside of the rut. The bull moose rut runs from late September into October. Bulls call with a low grunt, cows call with a longer wail, and bulls travel widely to find receptive cows. Fights between bulls involve antler-to-antler shoving and twisting and can end with injury or death; locked antlers are an occasionally documented cause of mortality for both animals when neither can disengage.

Danger to humans

Moose injure more people per year in North America than bison. This is partly because moose live close to settlements and roads across much of their range; collisions with moose are the leading cause of large-mammal vehicle fatalities in much of Canada and the northeastern United States. Cow moose with calves and bull moose in the rut are responsible for most direct attacks on people. The combination of speed (a moose can reach 35 mph), reach (the long forelegs deliver powerful kicks), and unpredictability makes a stressed moose extremely dangerous at close range.

Bison cause fewer total injuries because their range is more concentrated in protected areas with managed visitor distance. Yellowstone National Park records approximately one to two visitor bison injuries per year, almost always from people approaching within the posted 25-yard minimum distance. The injury pattern is different from moose: bison gore with horns and use their mass to charge and bowl over, rather than rearing and kicking with forelegs.

Frequently asked questions

Is the moose technically a deer?

Yes. The moose is the largest living member of the family Cervidae, the true deer family. It is also the largest of all living deer worldwide; the only larger cervid in recent history was the now-extinct Irish elk (Megaloceros giganteus), which was actually a deer rather than a moose despite the name.

If a bison and a moose were to fight, which would win?

A hypothetical that is not biologically supported by either species' behaviour, since the two are not natural rivals and do not compete for the same resources. A confrontation would advantage the bison on mass, the moose on antler reach. In practice neither species would engage; both would disengage and move off rather than confront a non-competitor.

Could a bison and a moose interbreed?

No. The two species are in different mammal families. Hybridisation between members of Bovidae (bison) and Cervidae (moose) is biologically impossible.

Where can both species be seen on the same trip?

Yellowstone National Park has reliable bison sightings (the park is the largest plains bison stronghold in the world) and moose can be seen in the willow-rich riverbottoms of the southern and northern park, particularly the Bechler River and the Soda Butte Creek drainage. Wood Buffalo National Park in northern Alberta has both wood bison and moose and is one of the few places where both species are visible in the same boreal forest habitat. Grand Teton National Park, immediately south of Yellowstone, has both species although the moose population is more reliably encountered.

Continue exploring

• Bison vs yak: how to tell two wild bovids apart
• Bison vs muskox: arctic vs plains bovid
• Yellowstone bison: America's last continuous wild herd
• Bison and buffalo size and weight figures
• American bison species deep-dive