Why do researchers want to put satellite collars on polar bears?

Satellite collars can give researchers information about the bears that they cannot get any other way. The collars provide a data-rich glimpse into the lives of single polar bears that gives us a representative sample of whole populations. Even Inuit who see the bears regularly do not see the same bear all the time, nor do most travel as far from shore as polar bears do. Indigenous knowledge is a valuable supplement to the vital information that collars provide but does not entirely replace them.

As the sea ice declines due to climate change, collared bears show us how their movements and activities may be forced to change with the changing conditions. This gives us important, real-time data on population responses to ongoing sea ice loss from carbon emissions—information that could serve as alarm bells to wildlife managers and policy makers.

What data do researchers collect?
Scientists collect location information, activity rates, and temperature data. Some collars record how much time a bear is spending in the water. The collars tell us such things as what habitat a bear is using at any given time. They also allow us to follow family groups and learn more about cub survival.

What bears are collared?
Only adult female bears can be safely collared – the necks of adult males are too thick, so a collar would just slip off over their heads. Younger bears are likely to grow rapidly, and current collars cannot accommodate those changes. This means we have less information about the movements of male and subadult bears, but more about females.

How do researchers put collars on bears?
The bears are first tranquilized with a sedative that make the experience safe for them and for the researchers. While the bears are tranquilized, researchers obtain various kinds of information, including the animal’s weight, length, and body condition. They also take blood samples that provide even more information, much like an annual doctor’s visit for people. Before departing, researchers carefully fit the collar on the bear. Back at base, researchers are able to confirm successful deployment by checking on collar movements. Some females simply do not like collars and pull them off once awake. In those rare cases, the research team goes back to the capture location and retrieves the collar for use on another bear.

What are collars made of?
Flexible, synthetic material that sheds water and ice and stays flexible in cold temperatures but is strong enough to withstand Arctic marine conditions for at least one year.

How long does the battery in a collar last?
A battery could last long enough that a collar deployed in one spring capture season could still be operating in the capture season of the following year (most polar bear work is done in the late winter and spring when the ice is solid, and the days are long). But collars can also fail and sometimes the bears remove them. So, if they last 12 months, scientists are pretty happy.

How do the collars come off?
The basic and most reliable release mechanism has a clock, and researchers can set the day that they want it to drop off. They usually set the timer so that the collar will fall off shortly before the batteries are drained and the collar is no longer transmitting. In addition to the timed-release mechanism, the collars are attached with steel nuts and brass bolts. In a salt water environment, this system eventually corrodes, causing the collar to fall off even if the release mechanism fails. Once they fall off, a GPS location allows researchers to find the collar (if in a retrievable spot), download any stored data, retrofit, and send it out again.

How many bears are collared each year?
This varies according to project goals, how well-funded a project is in a given year, and how successful researchers are in catching adult females.

How do collars affect the bears?
Scientists have no evidence that life-threatening injuries have occurred due to collaring from studies across the Arctic and over several decades. The most comprehensive study of this question found that “…collaring had no effect on polar bear recovery rates, body condition, reproduction or cub survival.”

Polar Bears International (PBI) appreciates the data that comes from collars, but we also appreciate that this method of data-gathering is intrusive. We understand that tranquilizing and collaring the bears runs counter to Inuit cultural attitudes about how to treat wildlife. For those reasons, we are concurrently supporting the development of less-intrusive monitoring methods.

Both small GPS ear tags and a new effort led by PBI and 3M to create better adhesive GPS tags look promising. If successful, this would allow researchers to track males and subadults for the first time.

What is PBI’s position on collaring bears?
PBI believes that the data provided by collars is not currently obtainable any other way. We believe that this data is critically important to the monitoring and management of the bears. We are supporting the development and use of other technologies, practices, and knowledge sources. We hope that in the future these may enable us to get similar results without using collars.

Rode, K. D., Pagano, A. M., Bromaghin, J. F., Atwood, T. C., Durner, G. M., Simac, K. S., & Amstrup, S. C. (2014). Effects of capturing and collaring on polar bears: Findings from long-term research on the Southern Beaufort Sea population. Wildlife Research, 41(4), 311. doi:10.1071/WR13225

Back