With a pack established by two naturally migrating wolves and their litter of pups born in spring 2021 in Colorado, Colorado Parks and Wildlife (CPW) biologists were interested in the opportunity to use and add collars as a part of our gray wolf monitoring toolkit.
Although three total tracking collars have been on members of the known wolf pack in North Park, Colorado, the collars are no longer functional.
One very high frequency (VHF) collar was deployed on wolf F1084 in Wyoming in 2017. The battery on the collar had a lifespan of 5 years and is no longer functional.
Two additional collars have been put on wolves in northern Colorado by CPW staff. Wolf 2101 had a collar attached in the spring of 2021 and wolf 2202 received a collar in the spring of 2022. Both collars had GPS (satellite) as well as VHF (radio) technology. Disappointingly, the GPS and VHF functions on both wolf collars have failed.
What are GPS and VHF collars?
Developed in the 1990s, GPS collars have helped revolutionize wildlife monitoring and research because they collect (and store) a high quantity of location information. They also provide information about animal movement patterns and survival.
CPW has used tracking collars for numerous wildlife monitoring and research projects in Colorado, including elk, deer, and cougars. VHF and GPS technology can even be used for transmitters deployed on birds, fish, and reptiles.
For the wolves in North Park, the GPS technology collected location points at a predetermined interval, stored them, and then communicated the data via satellite to CPW biologists. (CPW did not know exactly where a wolf was in real-time. Staff could view the newly collected location data every few days.) VHF radio collar technology has been around since the 1950s and works by the collar emitting detectable radio pulses that are transmitted on specific radio frequencies. To locate the collared animal, biological staff use equipment to detect the intensity of the radio pulses to locate the animals in the field.
While useful, tracking collars have limitations and imperfections.
The lifespan of GPS collars (e.g., how long it is collecting data or transmitting a signal) depends on how much data is collected. Typically, collecting more data results in a shorter collar lifespan. The lifespan of a collar is often shorter than a wolf’s lifespan, but not always. Collars continue to collect data and can tell us when an animal has died (stopped moving), so even if an animal dies before the collar does, they are still collecting and transmitting important information.
Once on an animal, collars can fail for several reasons. For example, there may be manufacturing defects that cause the battery to prematurely fail, or the collar may stop communicating with satellites, thereby preventing GPS data from reaching biologists.
There is a tradeoff between the complexity of the collar and its longevity. The more technology that is incorporated into the collar, the increased likelihood of failure. Simpler collars may be more robust and have a longer lifespan, but limited functions (e.g., VHF only).
Additionally, collars get beaten up, chewed by animals, and can fail from being out in the elements on a wild animal.
Confirming collar failures can be challenging. Close proximity to the animal in relatively open landscapes are best for signal detection. It may require several attempts locating and detecting a collared individual to confirm its collar status.
There are no immediate plans to collar additional animals at this point in time. Using helicopters to capture animals in the heat of the summer presents logistical challenges in addition to concerns about animal welfare. Because gray wolves have been relisted under the Endangered Species Act, CPW will need to coordinate with the U.S. Fish and Wildlife Service to conduct future capture operations. CPW plans to deploy more collars in the future for research and monitoring. CPW also plans to collar all of the animals that are used in the active reintroduction.
Where do we go from here?
Although unfortunate, what happened with these collars is not all that uncommon. Importantly, CPW does not plan to collar all wolves in Colorado because it would not be possible, and collars will not provide real-time location information. This highlights the need to diversify wolf monitoring and research tools.
This experience also demonstrates that it is important to develop conflict minimization strategies and programs that are not entirely reliant on having collar location information.
To confirm a wolf sighting, field biologists rely on observations like signs of tracks and scat. CPW also has a wolf sighting form available on our website and we encourage people to fill it out if they believe they have seen a wolf in their area. We ask that any photos or videos be included with these reports if available.
Written by Travis Duncan. Travis is a public information officer for Colorado Parks and Wildlife in Denver. He has lived in Colorado for nearly 20 years and loves the outdoors.