Stories

Secrets in the snow

Studying polar bears and other elusive Arctic wildlife through their footprints

Date: February 21, 2024
Author: Elisabeth Kruger and Natalie Reich

Polar bears—iconic symbols of the Arctic and beyond—are as elusive as they are majestic. But understanding how they’re faring is of utmost importance to scientists. These apex predators serve as a bellwether for the health of many other species and the ecosystems of the region’s oceans. In other words, if polar bears are thriving, we can infer that other wildlife in their habitat is healthy, too.

Conventional methods for collecting DNA samples from these bears to learn more about their status are both inefficient and costly. Fortunately, we’ve developed an exciting new way to gather this critical information that only requires the footprints that polar bears leave behind in the snow.

In a landmark study published in Frontiers in Conservation Science, WWF, and collaborators have unveiled an innovative method for extracting DNA from the snow tracks of three elusive carnivores, including polar bears. The new technique involves retrieving trace amounts of environmental DNA—known as eDNA—shed from the footpads of these animals in the snow, enabling the identification of individual animals.

WWF’s work in the Arctic is focused on protecting and restoring the ecosystems that wildlife and the people of the region depend on.

The climate crisis and conservation challenges

Polar bears face unprecedented challenges due to the climate crisis. Rapidly disappearing sea ice threatens their homes and food sources. The International Union for the Conservation of Nature (IUCN) predicts a significant decline—over 30%—in the global polar bear population by 2050. The study highlights the urgent need for effective conservation strategies.

eDNA: a game-changer

All animals shed DNA, including by sweating and breathing, as they move about their environment. Conventional methods for tissue collection typically involve locating bears by helicopter and either capturing them to retrieve samples or using a biopsy tool to safely collect DNA from a distance—both time consuming, expensive, and difficult practices. The breakthrough in this study involves non-invasive collection of skin cells from pawprints embedded in the snow, providing an additional tool for monitoring and understanding polar bear populations. Using eDNA sampling together with other monitoring methods provides more data that gives us a much clearer picture of the health of a given polar bear population.

The significance of snow tracks

Polar bear habitats are massive, and finding polar bear tracks is significantly easier than finding an actual bear. By collecting cells from snow tracks, scientists can retrieve eDNA without interacting with animals. The method has been refined through fieldwork in Alaska, Norway, and Sweden, leading to a protocol for collecting and preparing snow from tracks for laboratory analysis.

The hard-to-study polar bears

Studying polar bears poses numerous challenges, given their solitary nature, vast ranges, and limited accessibility for scientists. The data deficiency in many subpopulations complicates conservation efforts. The newly developed eDNA method offers a cost-effective and efficient way to gather crucial baseline data for understanding trends and implementing conservation interventions.

Participatory conservation

This technique is not limited to scientists; there is potential for other groups, including community members, volunteers, and other wildlife trackers to actively participate in monitoring and managing these bears. This approach supports WWF’s goals in the Arctic of bringing people with diverse backgrounds, experiences, and skills together in the preservation of these majestic creatures and their habitats.

The hope for impact

The eDNA method fills a critical gap in data gathering, offering a new way to collect information crucial for assessing genetic diversity and population resilience in the face of environmental changes and challenges like a rapidly warming planet. The technique also holds promise for studying other elusive species that leave pawprints in the snow, and scientists have already successfully used it with the Eurasian lynx and snow leopards—the other species talked about in this study. By expanding the toolbox for data collection, researchers aim to enhance conservation efforts and develop less invasive methods in collaboration with local communities.

An important advancement for conservation

Snow pawprint eDNA collection represents a significant leap forward in the conservation of elusive Arctic carnivores. As climate change continues to threaten these species, the people of the Arctic, and our oceans, innovative approaches like this provide hope for a future in which better data leads to more effective conservation strategies for polar bears and other wildlife. Through collaboration among scientists, conservationists, and local communities, we can unlock the secrets hidden in the snow and work toward a healthier Arctic for people and the planet.

Learn more about WWF's work on polar bears and in the Arctic.