A CIÊNCIAS researcher is taking part in an estimate of the polar bear population in a remote region of Greenland

Tiago André Marques, a professor at the Faculty of Sciences (CIÊNCIAS ULisboa) and a researcher at Centre of Statistics and its Applications (CEAUL) of the University of Lisbon, is taking part in an study published in March, which uses aerial surveys to provide the first estimate of the polar bear population in eastern Greenland, one of the most remote and least studied regions of the Arctic.

The results indicate an estimated population of 2,275 polar bears, revealing a significant number of individuals for a species classified as vulnerable and highly dependent on sea ice.

The study, led by researchers from the University of Washington and published last month in the scientific journal Endangered Species Research, is the first detailed survey of this subpopulation, which has never before been quantified.

Monitoring campaigns in eastern Greenland have so far been hampered by the region’s extreme isolation – comprising 1.5 million km² of sea ice – as well as by adverse weather conditions and the logistical challenges involved in carrying out field operations.

To obtain robust and representative data, the team carried out over 15,000 km of transects – routes along which sightings of the subject under study were counted and recorded – totalling 106 hours of flight time over 26 days between March and May 2023. During these flights, 84 groups of bears were sighted, comprising a total of 108 individuals, enabling the collection of essential data for the analysis.

Next, to calculate the total population abundance from this data, a field ecology method known as distance sampling was applied; in practice, this involved estimating the number of bears in the area based on a set of predetermined flight paths and the distances recorded to the animals sighted.

Polar bears are currently found in around 20 internationally recognised subpopulations spread across the Arctic. However, not all of them have been studied to the same extent, and there are still significant gaps in our scientific understanding of several of these subpopulations.

This new estimate helps to improve our overall understanding of the species’ status, and future research will combine this information with data on movement, survival and reproduction, providing a more comprehensive picture of population dynamics and resilience to climate change.

Dependent on sea ice to hunt seals – their main source of food – these animals face an uncertain future as their habitat shrinks, raising concerns about their ability to adapt.