Will climate change push gyrfalcons out of Sweden?

The gyrfalcon is adapted to live in the extremely harsh environment of the High Arctic. This powerful raptor can stay alive in –50°C, even during strong winter storms and almost complete darkness. But as TOM ARNBOM writes, climate change looks poised to outmanoeuvre Earth’s largest falcon. In Sweden, one of the gyrfalcon’s most southerly outposts, numbers are decreasing dramatically—and the decline may be a preview of the birds’ future in the High Arctic.

We are in the heart of Sweden’s Sarek National Park, far, far away from any road. It’s a wild and beautiful mountainous tundra landscape. Suddenly, we notice something dark approaching at high speed. It takes only a split second before all that remains to be seen is a cloud of feathers.

I will always remember this rare moment when I witnessed a gyrfalcon attacking a ptarmigan (a northern grouse) at more than 200 kilometres per hour. The power of this bird is enormous. But sadly, the power is no match for the climate crisis. This falcon evolved to withstand harsh, frigid weather, but its environment is rapidly becoming wet and warm.

With a wingspan that can reach 1.3 metres, the gyrfalcon is the world’s largest falcon, and it is found in all Arctic states. Gyrfalcons in the really far north have almost pure white feathers, while further south, they take on a more brownish colour.

Winter is the hardest time of year for gyrfalcons in the High Arctic. It becomes much harder for them to find enough prey because most other birds migrate south, leaving only ptarmigans.

The struggle to adapt to a warming climate

Of course, the gyrfalcons are not the only species struggling to adapt to higher temperatures. Polar bears must now cope with the loss of sea ice, and the Arctic fox has to compete for prey with the red fox, which has been migrating northward. The Arctic fox has also been hit by more frequent winter rains that affect the survival of its prey species, such as hares, ptarmigans and rodents: when heavy winter rains freeze over, an almost impervious crust forms that prevents hares and ptarmigans from digging down to hide from ferocious winter storms. The crusts also prevent them from finding food because the ice is too hard to break through.

But the gyrfalcons have an additional problem: they start breeding in early spring, often in old raven nests, on steep cliff faces or in gorges. But spring rains combined with strong, cold winds can kill the chicks.

We might be the last generation lucky enough to observe wild gyrfalcons in this part of the Arctic.

WWF, Birdlife Sweden and other partners are working together to monitor the number of breeding gyrfalcons in the Swedish Arctic. About 30 years ago, there were approximately 50 breeding pairs in northern Sweden. The biggest threat back then was people collecting eggs or chicks to keep or sell. The population slowly decreased, dwindling to about 30 pairs by 2015. Then in 2020 and 2021, we noticed a more dramatic drop. Many known nest sites were abandoned or contained only a single gyrfalcon. Only five known breeding pairs were found in 2021.

The reasons for this are not known, but climate change—several winters with considerable rain and strong storms—is the most likely culprit. The winter air temperature has increased by 3°C since 1960 in this part of Sweden. In Iceland, there are also indications that gyrfalcons have developed lead poisoning from eating ptarmigans injured by shotgun bullets. The injured birds are easier prey.

If we are lucky, this downward trend might be temporary. But sadly, it does not look good for gyrfalcons here. We might be the last generation lucky enough to observe wild gyrfalcons in this part of the Arctic.

For gyrfalcons, as with the polar bear and Arctic fox, the effects of climate change on populations are most visible and substantial at the southern end of the species distribution. Therefore, gyrfalcons in the High Arctic are likely still doing okayؙ—but the experience in Sweden should be taken seriously. It may be painting a picture of what we can expect in other parts of the Arctic soon.