Habitat model shows capacity for up to 1,000 bison in Banff

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Efforts to return bison to Banff National Park continue to move forward and a recent scientific study has shown the area identified for the species’ reintroduction could support up to 1,000 animals.

Researches from the University of Montana and Parks Canada officials collaborated on the paper, which was recently published online by the peer-reviewed journal PLOS One.

Parks Canada biologist David Gummer said the research assessed the potential habitat and carrying capacity in the Dormer and Panther valleys of Banff National Park for reintroduction of plains bison.

Carrying capacity, Gummer explained, is the upper limit of the number of bison that could theoretically be supported on the forage available on the landscape.

“It makes a lot of assumptions, but it is a very valuable approach to apply in a place like Banff where we don’t have (bison) out there to estimate these things directly,” he said. “It is also a really valuable example of how to estimate the habitat and how many you could support for any species reintroduction and it might be useful for other places in the world with the same problem This research actually helped inform the reintroduction plan.”

University of Montana researchers Robin Steenweg and Mark Hebblewhite were the primary authors of the paper, while Gummer, Brian Low and Bill Hunt were also involved.

The work analyzed the habitat in Banff National Park, specifically the two valleys where bison are planned for reintroduction, and developed a habitat model – called a habitat suitability model. It was based on a review of the literature about what habitat requirements bison have in other places where they are still on the landscape.

“The challenge in doing that kind of habitat assessment for Banff is that with bison not here at present, and with no detailed information on how the species would have historically used habitat in the wild on our landscape, it is challenging to evaluate the habitat,” Gummer said.

By taking the best information out there about bison habitat and combining it with details about the landscape in Banff, he said they were able to create maps of Banff National Park that show how much food or forage is available.

“Those maps are really valuable tools for Parks Canada because we can look specifically at the distribution of high quality habitat for bison and factor that into our reintroduction plan and future management actions,” Gummer said.

An important factor when determining carrying capacity is that the approach only considers a species using 25 per cent of available food on the landscape. So when researchers applied that approach to the areas in Banff being considered for bison reintroduction, they found that 600 to 1,000 animals could be supported.

Gummer said the research helped identify the Dormer and Panther valleys as ideal habitat for reintroduction. The combination of habitat quality, forage availability and space were highest for bison in those areas.

“It also gave us information on some of the surrounding areas in the park as well and what the habitat quality is in those areas,” he said.

“That really helps put this reintroduction area in perspective. In theory, it could support a significant number of animals and if successful it has great potential to contribute to plains bison conservation along with all those other sites in Canada and North America.”

Gummer said the upper limit of the carrying capacity should not be confused with a population target – it is not the goal to have upwards of 1,000 bison in Banff. What it does is reaffirm the feasibility of reintroducing bison in that specific location.

“Based on our habitat suitability model and estimates of nutritional carrying capacity, there appears to be sufficient habitat of high enough quality to support a relatively large population of plains bison year-round in Banff that could significantly contribute to improving their global conservation status,” stated the research paper.

An important factor when looking at carrying capacity is the season – as vegetation changes between summer and winter months. Gummer said the paper took that into account and created models for both.

“Bison are known throughout North America to shift distribution in response to season and weather conditions, so we created separate models for summer versus winter and even selected examples of years with different snow conditions,” he said. “The research reaffirmed there is habitat to support bison in both summer and winter.”

The paper was published in PLOS One – an online open access peer-reviewed scientific journal. Gummer said it is a good example of how Parks Canada is using science to guide all aspects of the reintroduction project.

In the abstract, the paper notes that plains bison in Canada are threatened and occupy less than 0.5 per cent of their former range.

“The largest threat to their recovery is the lack of habitat in which they are considered compatible with current land uses,” stated the report. “Fences and direct management make range expansion by most bison impossible. Reintroduction of bison into previously occupied areas that remain suitable, therefore, is critical for bison recovery in North America. Banff National Park is recognized as in the historical range of plains bison and has been identified as a potential site for reintroduction of a wild population.”

In the meantime, plans for the reintroduction to occur early in 2017 are proceeding according to schedule – as indicated by superintendent Dave McDonough at the annual planning forum in February.

Part of those plans include bringing four bison to Ya Ha Tinda Ranch in the national park, which is where Parks Canada trains its horses. It is also a popular area for backcountry horse users to travel through.

With that in mind, the four bison will be at the ranch so that horses that have never encountered a bison can do so in a controlled environment. Gummer said it is important to note that the four bison calves will arrive at Ya Ha Tinda mid-March and they are livestock, instead of from a wild herd.

“Feedback from equestrian users and our own equestrian specialists advised it would be highly advantageous for Parks Canada horses used for our operations in the field to get familiar with bison,” he said. “It is important to note that these four bison calves are a small transfer of bison as livestock between ranches. They will be maintained as captive livestock and will never enter Banff National Park.”

The bison that will be reintroduced next year will come from Elk Island National Park, likely in January 2017.

“We are on track and working towards that right now,” Gummer said. “Our focus is on preparing and documenting a lot of detailed planning for the reintroduction.

“That still involves detailed discussions with key stakeholders and the Province of Alberta, First Nations and having lots of discussions with bison experts to help form and shape the detailed reintroduction plan.”

The detailed environmental assessment for the reintroduction is still being completed and Gummer said he anticipates it will be available sometime this spring and will provide much more detail about the project.

Fencing is a detail of the reintroduction that has seen a lot of effort by Parks staff – with the issue of permeability a concern for stakeholders. Gummer said permeability for other species is a focus and Parks has been working on fencing that is not only effective for bison, but allows other species the ability to move in and out of the area.

Luckily, he added, fencing is an area other bison managers have learned a lot about already and experts made recommendations about what a fence would look like that is effective for bison, but also friendly for other species.

“We recognize this is an important consideration and that is why our current preparations for bison is testing some of that fencing in smaller experimental segments on the landscape,” Gummer said.

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