Satellite tracking for polar bear science and conservation

WWF’s new Wildlife Tracker offers a glimpse into the everyday lives of polar bears across different parts of the Arctic. It shows the incredible distances some bears travel, the relationship between polar bears and sea ice, and even gives insights into important events, like the first time females emerge from dens with their young cubs. Yet, this is only the tip of the iceberg of information that can be gained from following individual polar bears through time and space via satellite tracking.

Studying polar bears in the field

Satellite tracking has been a tool in the polar bear research and conservation toolbox for nearly 50 years. Although their scientific name, Ursus maritimus, means sea bear, in many other languages, the translation of polar bear is ‘ice bear’. Unlike most sea mammals, polar bears spend most of their time on top of the ocean rather than in it. One would think, therefore, that they should be one of the most straightforward marine mammals to observe and study.

But studying polar bear populations is far from easy. Polar bears are, for the most part, solitary. They also travel long distances and far from places inhabited by people. Finally, they are found only in the Arctic, where limited infrastructure and extreme weather make research logistics extremely challenging and expensive.

To successfully gather location data for an individual polar bear over time via satellite, the bear needs to be located, temporarily sedated, and fitted with a GPS tracker in the form of a logging device attached to a collar that is secured around the bear’s neck. Periodically, the logger beams the bear’s geographic location up to a satellite and the satellite beams it back down to a researcher’s computer.

Over time – weeks, months or even over a year – a detailed picture about the movements of that bear emerges. If multiple bears from the same subpopulation wear tracking devices at the same time, their movements can be compared. Patterns start to form. Over multiple years, scientists build an idea, supported by data, of how bears live in that part of the Arctic. Finally, over decades, tracking information can be used to paint a comprehensive portrait of how polar bears are coping in the midst of the climate crisis.

How tracking data reveals the impacts of the climate crisis

Much of the science about how polar bears are responding to the dramatic loss of their sea ice habitat comes from multi-decade-long research programs that include satellite tracking. For example, tracking of polar bears on Svalbard shows that some previously important denning sites on islands can no longer be reached by female polar bears, because the sea ice connection forms too late in Autumn and the bears are instead faced with hundreds of kilometres of open water.

The addition of a small salt-water sensor to GPS loggers helps to confirm when bears are in the ocean instead of on top of it. Bear behaviour has even been followed over generations to reveal captivating, yet troubling insights: “where her grandmother once walked on the frozen ocean, this female polar bear now has to swim” – Dr Jon Aars, Norwegian Polar Institute.

A combination of satellite tracking and wearable cameras has recently been used to describe behaviour of fasting polar bears in Western Hudson Bay. This declining subpopulation is being pushed closer to the edge of survival as sea ice melt causes bears to extend their fasting period over summer months. The technology revealed that while some bears rested and conserved energy, others roamed, snacking on land-based food sources. Nevertheless, all ultimately lost weight at similar rates. There is no easy solution to avoid starvation.

Both Svalbard and Western Hudson Bay have benefited from long-term tracking research programmes, and bears from these locations are currently featured on the WWF Wildlife Tracker. Researchers consider the information gained from satellite tracking to have made extremely valuable contributions to management and conservation of polar bears in the last several decades and deem it essential to continue. But the method is not without limitations.

Satellite tracking is one tool in the conservation toolbox

One major challenge of satellite tracking polar bears is cost. Satellite tracking devices and associated data downloads are relatively expensive, but these are dwarfed by field costs needed to locate suitable bears for tracking in the vast Arctic seascape. This means only a small fraction of a subpopulation can be monitored this way at any given time. For instance, tracking 20 bears out of a subpopulation of 2,000 unavoidably reveals only part of a picture. Further, only adult female polar bears can be tracked via GPS devices attached to collars. Young bears are still growing so collars cannot be fitted without risk of becoming too tight, and adult male bears have necks that are thicker than their heads, so collars slip off too easily.

Coastal Indigenous communities have lived alongside polar bears for thousands of years and have a wealth of Indigenous Knowledge about these animals and their ecosystems. Across some communities there are concerns about using satellite collars on polar bears, due to the chemical sedatives used, possible changes in behaviour following handling by researchers, the collars interfering with the bears’ ability to hunt, and the chance of collars causing abrasions and injuries, amongst others.

Conservation needs the best available information

Right now, the Arctic is undergoing a human-caused transformation. Do polar bears, which have been shaped over hundreds of thousands of years to be Arctic specialists, also have the capacity to be master adapters to the climate crisis? We don’t know, but we do know that in some parts of the Arctic, the changes are too fast for the bears to keep up. To inform management and conservation actions for polar bears, we need the best available information.

Along with science and Indigenous Knowledge, new tools such as eDNA from polar bear footprints in snow, and GPS trackers that can be attached to fur or via small ear tags are being developed to add to our collective toolbox. We must continue to learn from one another and work together to understand and safeguard polar bears in this changing world.

By Melanie Lancaster, Senior Specialist, Arctic species for WWF Arctic Programme