Where the Bison Roam: The Status of Bison in North America

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Marisa Lubeck: Welcome and thanks for tuning in for this episode of CoreCast. I’m Marisa Lubeck. Bison are an icon of North America. Images of buffalo herds roaming wild through the open plains have been symbolic throughout American history; however, bison today are restricted to less than one percent of their original range according to new research by the USGS, Department of the Interior and various other private and governmental agencies. I’m here with Peter Gogan, USGS scientist on the bison specialist committee. Good afternoon, Pete.

Peter Gogan: Oh, thank you Marisa.

Marisa Lubeck: Bison are an iconic species. I understand at one time, more than tens of millions wandered the plains from Northern Mexico all the way up to Alaska. How many bison live in the wild today?

Peter Gogan: There are some 430,000 bison in North America at this time, but the vast majority are in private ownership and raised for meat production. They are selected for their tameness and body conformation.

There's a saying in the bison breeding world, rump not hump, which shows what kind of body conformation they’re looking for. There are about 20,000 bison in conservation herds. Those are the herds managed by public agencies and private conservation organizations.

Marisa Lubeck: Is there only one species of bison in North American, and where are these animals mostly located?

Peter Gogan: There is only one North American species of bison, but there are two subspecies. The Plains Bison of the continent's grasslands and the Wood Bison of the Boreal Forests. Most bison are located in the western half of the continent with herds extending from Northern Mexico to Alaska.

Marisa Lubeck: Are bison in any danger of extinction, and what are some of the major threats that they face today?

Peter Gogan: American bison are not in danger of extinction. However, Plains Bison do show evidence of introgression of cattle genes, which means they’ve been hybridized with cattle. And this has been found even in many of Department of Interior Herds.

Also, some of the larger herds including Plains Bison in Yellowstone and Grand Teton National Parks, and Wood Bison in Canada’s Wood Buffalo National Park have been infected with livestock diseases. This creates special challenges in management of the animals.

Marisa Lubeck: Why is it important to maintain genetic diversity in these populations? It seems to me that 20,000 are quite a fair number.

Peter Gogan: That is a fair number if they were all in one herd. However, the isolated nature and small size of many of the bison herds, makes them potentially vulnerable to in-breeding depression. And this has already been documented in the Texas State bison herd.

The animals started to show very low reproductive success and very low calf survival, which are both characteristics of in-breeding depression. And it was getting to the point because there were no young animals being brought into the herd, that most of the herd was becoming quite old. Recently the State worked with a private bison owner to bring in some animals from a different location to reverse the problem, there in Texas.

Marisa Lubeck: In a recent report on bison that you co-authored, you talk about how bison shaped the landscape of North America. What do you mean by this?

Peter Gogan: Over their original distribution, bison influenced the structure, composition and stability of the plant and animal communities. This is such that they would eat some of the vegetation, mostly grasses and leave forbs and other plants for other species such as prong-horned antelope.

There were estimated hundred million bison wallows all over the plains of the continent that had a major effect on the hydrology and runoff of water from rains and snow melt. In some cases the ponds created by wallows were used by a couple species of toads as breeding areas.

Also, there are a number of grassland bird species that in the combination of bison grazing and fire created the habitat that these species needed for nesting success.

Marisa Lubeck: What were some of the major findings of this report?

Peter Gogan: The report recognizes that international cooperation across Federal, State and Provincial Governments and North American tribes and first nations are necessary to enhance the conservation of the species. Also that special attention is needed to maintain the genetic diversity in bison herds, with no evidence of cattle hybridization especially if these herds need to have satellite herds established so that genetic material is protected from any catastrophic events.

Some herds with history of cattle hybridization do contain unique genetic material and those also warrant conservation. Also, the known and potential livestock diseases pose a particular challenge to management and conservation of bison throughout the continent.

Marisa Lubeck: Pete, can you explain about the bison management working group that has been developed by the Department of the Interior and the USGS' role within this group?

Peter Gogan: The working group began as a grassroots organization where the natural resource managers for National Parks and US Fish and Wildlife refuges got together to discuss common concerns regarding management and conservation of bison within each of their units. Meetings would include Park Service and Fish and Wildlife Service Personnel along with some academics and some USGS personnel.

And we would meet on an annual basis. The meetings were quite successful typically at a park or refuge where we would look at the facilities that they had for management of bison and discuss the specific issues.

These went on for about 10 years and then the Secretary of Interior’s Office decide to create a bison conservation working group, which includes higher level people from within DOI agencies, especially National Parks Service, Fish and Wildlife Service, Bureau of Land Management, and also representatives from other Federal agencies such as the Forest Service and Department of Defense. And that group has really only just begun its work. It has had just a couple of meetings and is just right now setting out its agenda and timetable for its objectives.

Marisa Lubeck: After studying bison so extensively, what are the things that you admire or find exceptionally interesting about these animals?

Peter Gogan: The thing that I noticed especially about bison is that when you’re around them or near them, you really can’t help notice them. They are a strong presence on the landscape and my eye especially is drawn towards them. You can’t really ignore bison when you’re anywhere near them or even in seeing a large herd in the distance. They are just an impressive animal.

Marisa Lubeck: Thank you for speaking with us today Pete.

Peter Gogan: You’re more than welcome Marisa.

Marisa Lubeck: This podcast is a product of the US Geological Survey, Department of the Interior. I’m Marisa Lubeck. Thanks for tuning in.

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