Putting GPS collars on big game animals such as elk and deer helps wildlife biologists collect data about herd migration patterns they can use to gauge herd health, recognize wildlife needs and identify actions to take to mitigate human-wildlife interactions.
But for Brad Weinmeister, a wildlife biologist with Colorado Parks and Wildlife who has done field work like deer and elk collaring for 26 years, the gathered data often raises more questions than answers.
Weinmeister and his colleagues set out in mid-December for a deer-collaring project in Game Management Unit 741, a stretch of land southwest of Durango and south of Hesperus. It’s a new location for research, and the mission was to collar 30 members of a deer herd with a population size of 5,000 animals.
Every spring, typically in May, the herd migrates over 40 miles to summer in the countryside near Silverton. They travel the exact same route up and over the mountains every spring and return to the lower elevations of La Plata County every fall.
Weinmeister said previous studies have revealed winter closures in the game management area enforced by the U.S. Bureau of Land Management and CPW are important to the deer herd in question. The closures give deer acres of undisturbed natural habitat to roam all winter long.
The collars deployed this winter will remain fixed to the deer around their necks for two years. A timed detachment mechanism will release, the collars will drop off and Weinmeister will track them down for recovery.
Another 30 deer are planned to be collared next winter as the research continues.
The deer collaring will help wildlife biologists such as Weinmeister piece together how the animals live and survive on Southwest Colorado’s landscape and how they interact with people.
Data is mostly collected on a monthly basis, but Weinmeister can drill down into data points collected every two hours to monitor deer movement across U.S. Highway 160. He said he can essentially narrow it down to the hour of the day an individually collared deer crossed the highway.
That information helps interdepartmental mitigation efforts with entities such as the Colorado Department of Transportation to mitigate vehicle and wildlife collisions, he said.
Weinmeister finds it interesting the herd southwest of Durango travels the same route to Silverton year after year.
“Deer are very habitual in that they travel on the exact same path on these movements,” he said. “I’ll see movements like this with most animals where they’re moving on the exact same path. So there’s a learned trait there.”
Weinmeister said it would be fun to backpack through migration routes to learn more about the habitats on the ground. He hasn’t taken on such an endeavor, but he has done flyovers across portions of migration routes.
Aircraft are also generally an important tool for CPW’s collaring efforts. CPW published a news release on Dec. 1 noting collaring flights scheduled to take place across the Western Slope.
In addition to the collaring in Game Management Unit 741 and 74 in La Plata and San Juan counties, CPW scheduled work to collar 75 elk calves in December and 120 pregnant cow elk in March, focusing on the “Bear’s Ears herd in Northwest Colorado, the Avalanche Creek herd in the Roaring Fork Valley and the Uncompahgre herd west of Montrose.”
The research on pregnant elk calves is conducted in the early winter, which is also early in the elk’s gestation period, to prevent harm to the animals involved, according to CPW.
CPW Wildlife Researcher Nathanial Rayl said in the release the collected data from such efforts is critical to proactively manage elk populations.
“Elk, moose, deer and pronghorn prefer cooler temperatures and are actually less stressed than if we were to capture in the summer when they may overheat and die,” he said. “The deeper snow cushions the animal and helps prevent injuries, and they don’t run as far, making capture easier and quicker. Conducting this work in the winter also allows us to gather critical information about pregnancy and body condition.”
Weinmeister said his collaring efforts in the greater Durango area also provide insight into the mortality rates of deer populations over time. After eight hours of zero movement, the biologists receive a special notification indicating an animal has likely died.
“These animals are wintering, they are struggling to survive at that time,” he said. “Their nutrition, their food intake, is limited and they’re typically burning more calories than they’re taking in. If we have a hard, wet winter, typically (deer) mortality increases.”
In December, Weinmeister and other biologists relied on a helicopter to get to the herd southwest of Durango. From there, a crew member armed with a net gun would target the deer for immobilization.
The helicopter would then land and deploy two biologists, who would restrain the captured deer and blindfold it before collaring and releasing it, he said.
The collars are simple hardware a little smaller than a person’s fist. Weinmeister said they are equipped with GPS technology, a battery pack and a storage unit on the bottom of the device.
The devices are attached to collars that fit around an animal’s neck. Biologists attach them so they aren’t too tight and aren’t loose enough to rub against the animal.
Retrieving collars, which have timed automatic detachment mechanisms, can be interesting on its own because it’s hard to predict where a collar might have dropped. One would be surprised at where animals have came and went, Weinmeister said.
“I had a bighorn sheep that had a radio collar on it that got caught in an avalanche,” he said. “I went out to pick up the collar. It was about 6 feet up in a tree. Because that’s just the depth of the snow when that avalanche slid.”
He also said tracking movement patterns has reinforced the idea the animals all have unique personalities.
cburney@durangoherald.com
