Bison Calf Behaviors and Their Interactions with Mother Bison

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Bison Calf Behaviors and their Interactions with Mother Bison

Kelci Wunderlich: kelci.wunderlich@mnsu.edu

June 26, 2012
INTRODUCTION
Yellowstone National Park, a place in which Birds fly free, Elk and Bison roam the valleys, and the Bears and Wolves tie the food chain together. The first animal observed just in the gates of Yellowstone National Park was a lone Bison; immediately a point of interest for the group. The Bison (Bison bison) is the largest land mammal in North America, and in a typical year approximately 3,000 Bison roam through the valleys of Yellowstone National Park (National Park Service, 2012). Until the reintroduction of wolves into Yellowstone, adult Bison didn’t have any predators. Observed first-hand, the Mollie Wolf Pack does in fact kill adult Bison which will also bring forth the motherly instincts of Bison to protect their young. In a study conducted by Smith et al, wolves were more successful in killing elk when they were first released into Yellowstone, but when the elk became scarce some of the wolf packs learned how to kill injured Bison and Bison calves, and since have succeeded in killing any adult or Bison calf (Smith et al, 2000). Bison Calves were the true eye-catcher in the many herds of Bison observed at Yellowstone; they were born in May as their size was still very petite as they stayed in close contact with their mothers at all times (Green, 1993). Calves are able to keep up with their herd in as little as 3 hours after they are born, but their mothers still maintain a close watch on them as they are suspect to becoming the prey of wolves or grizzly bears (Wolff, 1988). In a study conducted in Wood Buffalo National Park, the herd would take many different precautions in order to protect their calves such as: the mother and calf would walk in the front of the herd when there was a wolf sighting, and the bulls would take up the back of the herd to offer more protection (Carbyn and Trottier, 1988). The “Landscape of Fear” study conducted in Yellowstone after the introduction of wolves into Yellowstone demonstrated that female Bison with Calves were in fact noted to show more vigilance than in previous years when wolves were not in the park (Laundre et al, 2001).

As in all animals fitness is extremely important making protecting the young of the herd an even more important task. The mothers of the Bison Calves along with the Bulls of the herd will put themselves in the path of any predator that comes in the way of them and their young. Even if an adult Bison is killed in the process, their overall fitness will still prosper as the young of the herd have been saved by his/her actions (Fuller et al, 2007). Bison Calves are normally weaned off of their mothers when they are around 6 months old in which they start to fend for themselves, and defend their territories from any predators (Green, 1992). While observing the Bison Calves a hypothesis was drawn: Until Bison Calves are weaned from their mother and can defend themselves, they will spend majority of their time interacting with their mother, and less time performing behaviors that don’t require interaction with their mother.

METHODS & MATERIALS
The site of observation was in the Lamar Valley of The Yellowstone National Park in Wyoming. The first three hours of observation took place at a temperature of 65-70 degrees with an overcast cloud cover between the hours of 9 a.m. and 12 p.m. The last hour varied from overcast to a light-moderate rain with temperatures cooling off as evening set in at approximately 5:30 p.m. The materials needed for this observation were very minimal as the area in which the observation took place was set up. Dr. Krenz was the van driver who found us the best herd of Bison to observe to answer questions and hypothesis. Binoculars were used to keep track of the Bison Calves as they were free to roam wherever they pleased. Scopes were another viewing tool used as the...
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