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Ecological Impacts of the Banff Bison Reintroduction

Over the past couple of months, I've started working on a very exciting new research project that will (hopefully) form the majority of my PhD thesis. The reintroduction of bison in Banff National Park, where they previously occurred until extirpation by excessive hunting 150 years ago, has caught the attention and imagination of many. After all, how cool would it be to be hiking in Banff and come around a corner to see a herd of bison peacefully grazing in a valley? Speaking from experience, having spent 9 days near the bison soft-release pasture, I can say: very very cool. Another human aspect to this project is the cultural significance of bison to First Nations people in the area; restoring bison to their traditional homes is another small step of the reconciliation process.

Aside from the general awesomeness, though, there is a lot of behind-the-scenes research, planning, and management that has happened, and continues to happen. Now that the bison have officially been released from their pasture into the larger, unfenced reintroduction zone, many are watching to see what they do next. From an ecological perspective, this reintroduction comes with a lot of questions to be answered. How will the bison impact other species in the park, from the plants they browse and graze to the insects, birds, other large ungulates, and of course, predators? Bison are often referred to as "ecosystem engineers", due to their significant impact on all trophic levels in their habitats. From simply eating (grazing on grasses, browsing on low shrubs) and walking around, to wallowing, trampling, and even defecating and dying, bison affect the entire ecosystem. Previous research has showed that these huge animals put areas under intensive grazing and browsing pressure, and while large numbers of bison may overwhelm the ability of plant communities to recover from this, lots of prairie plant species are very resilient to grazing and actually thrive under heavy pressure. Bison may promote the plant species diversity in an area and increase the abundance of rare plants by suppressing the growth of grasses, which tend to out-compete other ground cover plants, allowing forbs to grow more. They also graze at lower levels on shrubs than most deer and elk, so shrubs will put out taller stems that bison can't reach but that provide tasty snacks for longer-necked ungulates. Bison dung enriches the soil and their urine improves soil nitrogen content; dung also attracts bugs which in turn support lots of insect-eating birds. And the bison themselves (if they can be caught) provide large meals for predators, such as wolves and bears, and scavengers like coyotes, foxes, mustelids, and birds.

My role in this project comes from the ground up. Banff National Park has had 150 bison-free years to reach its current state, but we expect that to change with the presence of these big bovines. In July, I spent a week and a half travelling the bison reintroduction zone and conducting detailed vegetation surveys, creating a baseline inventory of what the shrub and grass occurrence, abundance, and biomass look like now. However, ecological research isn't a short-term investment, so this is just step one of a long-term study that will involve repeating our surveys in a few years, once the bison have had a chance to use the area, and seeing what has changed. With my data, I will be able to detect changes in where and how much grass occurs, the biomass of woody shrubs in the area, the formation of bison wallows, and possibly even changes to the riparian zone along the Panther River where the bison access to drink or cross.

I'm very much looking forward to digging into my data and starting the analysis, building a picture of the pre-bison reintroduction zone. But what will really be cool is when we go back in a few years and re-survey; that's when the bison-mediated changes will become evident and when we can really quantify the effect that North America's largest land animal has on its environment. In a time where species conservation is full of stories of declines and losses, it's a real privilege to be involved with a project that is actively looking to restore species to where they once were.

And hey, look - my research and I made it onto TV! Thanks to Global Morning Calgary for having me on to chat about bison ecology in Banff.

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