Mule deer have been dying off in parts of Wyoming for some time. But until recently, it was unclear how acute the problem was. That’s because the Game and Fish Department wasn’t getting an accurate count of how many deer there were. Now, the agency is trying out a new method for estimating deer populations. It’s much more expensive … but officials say it’s worth the cost because it will help them maintain a healthy deer population. Wyoming Public Radio’s Willow Belden reports.
WILLOW BELDEN: It’s a sunny morning in the Platte Valley. A group of researchers from the Game and Fish Department and the University of Wyoming have parked their trucks amongst the sage brush. Their project for today is to put GPS collars on mule deer.
BELDEN: You catch mule deer with a helicopter. The helicopter shoots a big net at them … and then flies the deer back to the researchers, two at a time. The animals are blindfolded, and their legs are tied together, so they can’t flail around much. But that doesn’t stop one of them from voicing his displeasure.
AMBI: mule deer making mule deer noises
BELDEN: The female stays quieter, as the researchers hoist her up and weigh her.
AMBI: scale clanking
BELDEN: They lay her down on a tarp, draw a blood sample (to see if she’s pregnant) and check for lice. They do an ultrasound on her rump to measure body fat. And finally, they get to the main task: putting a GPS collar on the doe’s neck. Once that’s done, she’s ready to be released. The researchers remove her blindfold and loosen the leather straps binding her legs.
AMBI: straps being loosened
BELDEN: The deer takes a startled look around and then bounds off behind a rock outcropping.
From now on, her GPS collar will give off regular signals, which will let Game and Fish track where she is. The agency has collared dozens of deer as part of their new system for estimating the size of the herd.
In the past, Wyoming used computer simulations to estimate deer populations. They’d plug in hunter harvest numbers and other data, and the computer would generate a number. But the public thought those numbers were too low.
Tom Ryder is assistant chief of the wildlife division at Game and Fish. He says the public was right – the agency was over-estimating the number of deer. And he says that’s a big problem, because Game and Fish uses those numbers to set hunting quotas.
RYDER: If you are inaccurate in your herd estimate, and you increase your quotas for deer harvest, you may actually be taking more deer through hunter harvest than the population can withstand through time…
BELDEN: …and Platte Valley residents say that’s been happening. Which is bad for the deer, and bad for local businesses. Valerie Condict and her husband are outfitters in the area … and they say they’ve had to reduce the number of hunting trips they lead.
VALERIE CONDICT: We have clients that usually come year after year and hunt with us – some of them have been coming six, seven, eight, nine years – and quite a few of those elected not to come back and hunt until they saw an improvement in the quality of the deer.
BELDEN: So Game and Fish is trying to bring the Platte Valley deer population back up to where they want it. They’ve drafted a new management plan, which calls for improving mule deer habitat and capping hunter numbers. To figure out where to cap the numbers – and even to determine how many mule deer the landscape can support – they need an accurate count. And that’s where this new technique – called a sightability survey – comes in. Will Schultz, the wildlife biologist at the Saratoga Game and Fish office, is overseeing the sightability survey.
WILL SCHULTZ: We use a helicopter with two observers, and we’re physically counting the deer that we observe.
BELDEN: As in, counting ALL the deer – not just a sample. They fly back and forth for days on end to cover the entire territory. Of course, they still miss some deer. So they use the GPS collars to estimate their margin of error.
The technique isn’t new. Idaho has been using sightability surveys since the 80s … and other states have adopted the method as well.
Mark Hurley of the Idaho Department of Fish and Game says his state has been happy with the results.
MARK HURLEY: No survey protocol is perfect, but as far as we’re concerned this one is probably the best.
BELDEN: This is the third year that Wyoming is trying out the model in the Platte Valley, and officials from Game and Fish say they’re getting much more accurate deer counts than they did with the old method. They’d like to start trying it out on other herds throughout the state.
But there’s a problem: cost. Again, Tom Ryder with Game and Fish.
RYDER: The sightability survey is running about fifty thousand dollars per crack. At that type of a cost estimate, the department can’t afford to fly that intensive a survey in every single deer herd in the state, every single year.
BELDEN: The good news is that once you have reliable baseline numbers, you can do the sightability surveys less often – say, once every five years. In between, you can do computer simulations. And that may even out the cost over the long term.
Game and Fish plans to try out the technique near Pinedale and Glenrock next … and could start using it across the entire state in the future.
For Wyoming Public Radio, I’m Willow Belden.