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- Active during day (diurnal). Intermittent grazing and ruminating throughout a day, led by a cow.
- Move about 3 km (1.9 mi) per day, but varies according to habitats, presence of biting insects, water. (Meagher 1986)
- Several times a day in summer, engage in wallowing to put dirt and dust into their hair (keep insects off the skin, protect against heat) (Lott 2002)
- Plains Bison are non-territorial and are nomadic
- Plains bison living in small herds may be non-migratory with fidelity to a home range (Guthrie 1990)
- When free-ranging, are seasonally migratory, moving to lower or more southerly habitats in winter. (Nowak 1999)
- Distances traveled between winter and summer territories may be up to 40 km (25 mi) in mountainous habitats and 240 km (149 mi) in boreal-forest parkland habitats. (Meagher 1986)
- Bison are gregarious, forming fluid groups of females with calves, young males up to 2 or 3 and possibly a few older males.
- Breeding age males play no role in calf raising and normally do not mix with the cow and calf groups
- Males live alone or in small herds of males.
- Groups of adult females with their young in one study of free-ranging individuals in Montana averaged 57 individuals. (Nowak 1990)
- Dominance in males is linear
- Top bull dominates over all of group
- Bull with 2nd most dominant role dominates over all the group except for the top bull.
- This pattern continues down the ranking, so that subordinate males only rarely challenge the order
- Dominant bulls have higher cortisol levels, indicating that their social status makes for significant physiological stress during rut. (Mooring et al 2006)
- Dominance strongly correlates with age and weight in bachelor groups (Roden et al 2004)
- Bison are nomadic, may move several miles a day while feeding. (Lott 2002)
- Amount of movement influenced by quality of habitat's plants, presence of biting insects, amount of water available (Meagher 1986)
- Bison herds moved 3.2 km/day in a montane valley to 2.8 km/day in coastal scrub-grassland (Meagher 1986)
- In shrub-steppe habitats of Southern Utah, herds remained in one area about 2 days. (Van Vuren 1983)
- About 5 to 10 percent of bulls' challenges lead to fights. (Lott 2002)
- When bulls threaten, they may bellow, stamp feet and snort, approach each other with tails high (Lott 2002)
- When fighting, bulls run together, clash heads, then push upwards with heads held low. (Lott 2002; Guthrie 1990)
- Cattle fight in a different way, by hooking with horns, then pushing. (Guthrie 1990)
- Relatively short horns of B. b. bison allow a bull to slip to the side after head clashing and gore an opponent; such wounds are frequent (Guthrie 1990)
- Bulls may approach closely, heads turned sideways, then nod the head up and down until one may attack or submit before an attack; called a "nod threat" (Lott 2002)
- Turning the head sideways when two bulls threaten as they face each other, indicates submission; then the contest is over and the winner does not attack. (Lott 2002
- Broadside threat posture displays give best view of overall large body size; may intimidate opponents into submission (Lott 2002)
- Bulls may bellow when threatening each other.
- This sound has been compared to a lion's roar and can be heard up to 5 km (3 mi) away. (Meagher 1986) (Buchholtz & Sambraus 1990)
- Males that are competing with each other may wallow, then urinate in the wallow and roll in the urine before resuming their challenges (Lott 2002)
- Females have also been observed urinating into wallows and rubbing their necks on the soil. (McMillan 2000)
- Bulls use a lip curl and tongue (flehmen) to transfer cow's hormone-packed urine to a receptor organ in the roof of his mouth. (Lott 2002)
- Gaits include walking, trotting, galloping, bounding. (McHugh 1958)
- Can run up to 60 km/hr (37 mph)
- Known to leap over barbed wire fences; surprising agility for animal its size
- Good swimmers; can swim rivers at least 1 km (.6 mi) wide. (Meagher 1986)
- Bison grazing in Flint Hills of Kansas increased abundance of Upland Sandpipers, Grasshopper Sparrows and together with the effects of recent prescribed burnings, lowered numbers of Dickcissel. (Powell 2006)
- Human prescribed burning plus intense bison grazing may lower numbers of four grass-dependent species of sparrows and Eastern Meadowlarks, and shrub-dependent Bell's Vireos. (Powell 2006)
- After grazing by bison, there are fewer plants, but more species; grazing increases diversity of grassland species, as does a fire. (Lott 2003) (Powell 2006)
- Grazing bison keep grasses short, which promotes prairie dog colony survival; prairie dogs don't live in areas with tall grass where they can not see approaching predators. (Lott 2003)
- Bison are attracted to bare dirt for dusting fur in prairie dog towns.
- Brown-headed cowbirds (Molothrus ater) forage on insects disturbed by grazing bison.
- Sedges and rushes (water loving plants) grow in compacted bison wallows that can hold extra rainfall. (Lott 2003)
- Many other ungulates co-exist with bison using different foraging techniques and plant preferences
- Native Americans living in bison habitats depended on bison for much of their subsistence.
- Bison fertilize the grasslands.
- Play behavior peaked at dusk for young bison. (McHugh 1958)
- Young bison play more than adults. (McHugh 1958)
- Young often engage in wallowing during play (McHugh 1958)
- Juveniles chase, play-mount, butt heads (but don't lower heads when doing so)
Adaptations for Winter
The winter coats of American bison—composed of wooly under-hairs and tougher, water-resistant top hairs—make them superbly adapted to harsh weather conditions.These heat-retaining hairs are molted during warmer seasons.
Historically, their coats were valued by native peoples and settlers for their thermal qualities.
Image location: Yellowstone National Park, Montana.
Image credit: © Carra, Lexington, Kentucky. Made publically available via Wikimedia Creative Commons license 2.0.
Meagher (1973, 1986)
Roden et al. (2004)
Van Vuren (1983)
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