Elk Island National Park of Canada
Phenotypic Differences Between the Bison Subspecies
Historic range of plains and wood bison.© Parks Canada
The differences between plains and wood bison can be separated into two groups; pelage characters and structural characters. Plains bison tend to have pelage characters which are larger and more obvious than those of the wood bison. Whereas plains bison have large chaps, a full beard and neck mane and a well-demarcated cape, wood bison have no chaps, a thin pointy beard, a rudimentary neck mane and a cape that grades smoothly back to the loins. Structurally the highest point of the hump on a plains bison is directly over the front legs while the highest point of the wood bison is well forward of the front legs. There are differences in weights as well with the wood bison being considerably larger than the plains. The Park maintains a bison weight database going back to 1956 and during all that time there is only one record of a plains bison bull weighing more than 2000 pounds (909 kg) while over one-third of the wood bison bulls exceed this weight.
There has been some discussion as to whether the subspecies are simply ecotypes, and that if a wood bison was placed in plains bison habitat, or vice versa, it would assume the traits of the host bison, simply due to the environmental pressures under which it is placed. A large-scale phenotyping study was conducted during the early 1990s where almost every publicly managed bison herd (both plains and woods) was examined for its external phenotypic expression, and it proved that, despite the habitat in which they reside, they maintain the traits which characterize the subspecies. Recent research at the University of Alberta has conclusively proven a genetic difference between the two subspecies.PLAINS BISON
Plains bison bull.© Parks Canada / EI9912310025, 1991/12/31
- The highest point of the hump is directly over the front legs.
- Large thick chaps on the front legs.
- Thick pendulous beard.
- Full neck mane which extends below the chest.
- Sharply demarcated cape line behind the shoulder.
- Thick bonnet of hair between the horns.
- Cape is usually lighter in color than the woods.
- About one-third smaller than a wood bison of similar age.
Wood bison bull.© Parks Canada / EI9912310026, 1991/12/31
- Highest point of the hump is well forward of the front legs.
- Virtually no chaps on the front legs.
- A thin scraggly beard.
- The neck mane is short and does not extend much below the chest.
- The cape grades smoothly back towards the loins with little if any demarcation.
- The forelock lies forward in long strands over the forehead.
- The hair is usually darker, especially on the head.