Why Do We Capture and Collar Polar Bears?

Ask An Expert: Why do we still capture and collar polar bears for research?

Q: If we’ve been monitoring polar bears for decades, why do researchers still need to capture and track polar bears?

The polar bear lives in a rapidly changing environment. The sea ice, which is the species' most important habitat, is disappearing and changing. It seems intuitive to think that the best management is to leave nature alone. But for a completely protected species in a changing climate, that is not enough.

In Norway, nature management is based on knowledge. The information we gain from our research is used for population assessments, traffic regulations, emergency preparedness, land use and measures to reduce conflicts between polar bears and people. It is used to understand how climate change is affecting the species and to distinguish between natural fluctuations and real warning signs; between what is natural variation and what is a sign of a population under pressure.

Seeing a bear from a distance tells us that it exists – but not how it is doing.

To get meaningful numbers on polar bear survival and reproduction, it is important to physically handle a number of animals each year. Capture is still necessary to collect biological samples and reliable information on reproduction, age structure, survival and area use using GPS (tagging).

Our monitoring work is carried out by helicopter, and on board there are two biologists, a veterinarian, a pilot and a technician. We immobilize the polar bear from the helicopter with a small dart containing a drug that causes the animal to fall asleep after three to ten minutes. It is then safe to land, and we can tag the bear with an ear tag and a microchip and by tattooing a number on the underside of its lip. Having multiple ways to identify a bear is important because they may lose tags or a tattoo may not be readable. It also allows us to learn more about male bears, who can’t wear collars because their necks are too thick and pointed — the collars slip off. This year, for example, we learned that a 9-year old male bear travelled from Svalbard, Norway, to the east coast of Greenland where it was shot by local hunters, identified by the ear tags.

We also take measurements and samples of blood, fat and hair. Through these samples we can gain knowledge about body condition, health, nutrition, immune activity, physiology, stress, disease and environmental toxins. This is information that cannot be read from a photograph, a binocular observation or a track in the snow. Once we have the data we need, the bear is given a drug that neutralizes most of the active substance. Most polar bears are up and walking 10–15 minutes later.

Collars give us a unique insight into the lives of polar bears

Some adult females are fitted with satellite collars that allow us to track where the animal moves. We can follow migrations over long distances, even when they are in areas where we cannot observe or capture them. This allows us to identify important habitats and understand how bears are adapting to a changing Arctic. Without this knowledge, we would largely have to guess. For example, we learned that a female was able to navigate across a glacier crisscrossed with deep crevasses. We have also seen that bears can swim many hundreds of kilometers.

In this year’s fieldwork in Svalbard…

• 41 polar bears were examined

• 6 females received collars

• 50% of females had cubs, and they were mostly in good shape

The results so far indicate that the polar bears in Svalbard have fared well, even though there is less sea ice.

From our long-term research, we know that…

• Adult females have a survival rate of around 97 percent from one year to the next.

• 1 in 3 cubs survive the first year of life: high cub mortality is a natural part of the polar bear life cycle. Cubs die of starvation if the mother does not provide enough milk. Polar bear mothers live on the edge after five months without eating in early spring before they start hunting again. In addition, male bears will kill cubs in the competition for females.

• 10-15 year-old mothers have cubs that do better than younger or very old mothers do.

• 20+ year old-mothers have fewer cubs.

Avian flu detected for the first time in a polar bear in Europe

Polar bears don’t seem to be often affected by disease. However, epidemics are a potentially serious threat to a species where survival of adult individuals is initially high. This month, the Norwegian Veterinary Institute detected bird flu in a one-year-old male polar bear, after tourist guides reported a dead polar bear. This is the first time the virus has been detected in polar bears in Norway and Europe. Several polar bears have been found to have been infected with bird flu in both Canada and Greenland.

Environmental toxins can also lead to death. These substances are used in industry, agriculture and clothing production, and they travel to the Arctic with air or ocean currents. We still know too little about how the total load of environmental toxins affects each individual polar bear and the population over longer periods. Investigations of such levels, and how they affect individuals, are therefore an important part of our work.

In the coming years, we will have increased focus on diet studies, to better understand how polar bears have been able to stay in good shape, despite the rapid warming of the air and water, and the loss of sea ice and glaciers.

Having too little knowledge is a risk

This year's fieldwork has so far shown no signs of a dramatic decline in the population in Svalbard. But there is also no reason to sit back. When habitats are changing as rapidly as they are now, having too little knowledge is a management risk.

Every handling of a polar bear must still be justified, and it is important to acknowledge that research involves intervention. Immobilizing and handling a polar bear causes stress, and we take that seriously. However, our experience, which is also supported by other research, shows that the methods we use pose a low risk of permanent injury or death. This does not mean that risk does not exist, but that it must be assessed against what we gain: the knowledge that enables us to manage the species better.

The conclusion should still be clear: without capturing, we would have far less knowledge about how polar bears actually cope. And without that knowledge, management is weaker. The goal of monitoring is to know enough to protect the polar bear as best as possible.

Jon Aars is a chief scientist and Dag Vongraven is a senior advisor with the Norwegian Polar Institute. This article originally appeared in Svalbardposten. It has been translated from Norwegian. https://www.svalbardposten.no/forvaltning-isbjorn-norsk-polarinstitutt/hvorfor-vi-fortsatt-forsker-pa-isbjorn/615069