State big game biologists conduct two mule deer surveys every year.
Biologists are flying aerial surveys in the rugged terrain of the badlands to look at population demographics of mule deer.
"We determine a buck-to-doe ratio, which is expressed as bucks per 100 does. And then we're also interested in assessing this year's fawn production or fawns per does again expressed in fawns per 100 does," said Bruce.
Stillings says the fall aerial mule deer survey is the first indication of this year's mule deer fawn production.
"It'll give us a really good idea if we should expect population growth when we resurvey these areas again in the spring to determine population abundance," said Bruce.
In order to fly aerial mule deer surveys, leaves must be off the trees and no snow on the ground to get an accurate count.
"When you have snow on this broken terrain, when you're searching out white mule deer rumps, many times when you're looking from the air, when you have that scattered white, patchy snow across the broken landscape, it can make it really difficult to find those white rumps," said Bruce.
And there's a large area to cover when conditions are right.
"We'll have 6 different airplanes going out and doing these surveys. We have 26 areas that we've been surveying since as far back as the early to late 1950s. So each area ranges in size from as small as 7 square miles to as large as 17 square miles," said Bruce.
Biologists arrive at survey locations at sunrise to take advantage of the first couple of hours in the morning when mule deer are most likely to be out and observable.
Stillings said in 2012 there was record low mule deer fawn production. However, since 2013, fawn production has improved and population trends have increased.