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Science and Innovations

AZGFD Tracks Mule Deer Movement Near Flagstaff

Arizona Game and Fish Department

The Arizona Game and Fish Department put radio collars on twenty mule deer near the San Francisco Peaks north of Flagstaff, to track their movements over the next three years. The data will identify wildlife corridors where deer travel from one place to another, and may eventually lead to highway projects that create safer roads for both drivers and deer. KNAU’s Melissa Sevigny spoke with biologist Jeff Gagnon about the federally funded experiment.

Melissa Sevigny: Can you give me an idea of how widely the mule deer in northern Arizona are roaming and places where they might be trying to cross highways?

Jeff Gagnon: If you took human development out of it, those animals would be able to travel as far as they needed t to survive. In the case of some of the animals in Wyoming, some of those mule deer can go 100 miles or more between their winter and summer ranges. In our case because of the highways like I-40 and I-17 those animals are really limited on their ability to move. They don’t try to cross roads that often and when they do cross roads the risk of getting hit by a vehicle is pretty high.  

So why put radio collars on mule deer, what can you learn from that kind of information?

Basically whenever we collar an animal we learn something, you’ll learn movement paths and habitat that they select…. In this particular instance we’re looking at corridors… We know they may spend time in winter range or summer range, but we don’t know how they get there, and the reason that’s important… The key goal is to keep habitat fragmentation is happening, so if an animal gets blocked from moving from its summer to winter range, it can’t survive as easily, so we try to find ways to promote that movement.

Habitat fragmentation, what is that?  

Basically it’s taking an area an animal lives in and cutting down into an area where it’s harder to survive. For example, for us, if we live in an area where we can get to the local restaurant for food, and be able to go get resources at the grocery store, and then someone puts a wall in the way, then you wouldn’t be able to get to the grocery store and now you have to go to the local Circle K, and eventually if you get chopped down further and further you might be stuck in your house at some point and you can’t survive at all. That’s what habitat fragmentation can do to wildlife, it makes it harder for them to survive as the areas they live in get smaller and smaller and they can’t get out of them.

And this is happening because of highways, fences, roads, things like that?

Highways, fences, roads, development, can even be railroads, canals. There’s a lot of things that can happen that keep animals from moving around their habitat normally and get to areas easier for survival.

How can this data potentially lead to fewer collisions on the roads with mule deer?

One of the things we’ve done in Arizona is we’ve used GPS data to look at where to put wildlife crossings for wildlife to get across roads safe. One of the better examples of that in our state is highway 93 near Hoover Dam, where we had bighorn sheep getting hit by cars. Now what you’ll see there is these overpasses, and we had six thousand or more sheep cross those in the first four years, they were working really well. That’s the best example of how we use GPS data to reduce the potential for animals to get hit on the road, but also keep that habitat fragmentation from happening. Ideally with a project in Flagstaff… if there’s an area on one of the highways where animals are getting hit, having that data makes it a much more powerful tool to help make a decision to do something like that.

Jeff Gagnon, thanks for speaking with me today.   

Thank you.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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