New Study Reveals How Climate Change Is Reshaping the Breeding Season for Arctic Falcons

The Arctic is warming faster than almost anywhere else on Earth. A newly published study is one of the first to compare across the entire Arctic how that warming affects two of the region's top predators. The research, published in Global Change Biology, brought together researchers from more than a dozen institutions, including Michael Henderson, Program Manager for The Peregrine Fund's Gyrfalcon & Tundra Conservation Program. Together, they compared breeding patterns in Peregrine Falcons and Gyrfalcons at monitoring sites across the Arctic, from Alaska and Canada to Greenland, Iceland, Scandinavia, and Russia.

Two Species, Two Different Lifestyles

Peregrine Falcons migrate long distances each year, while Gyrfalcons typically stay in or near the Arctic year-round. That difference in lifestyle turned out to matter a great deal. Researchers analyzed thousands of nest records collected over decades and found that both species tend to hatch their young earlier in years with warmer spring temperatures. But Gyrfalcons, as year-round residents, adjusted their timing more strongly than the migratory peregrines. Because Gyrfalcons stay close to their breeding grounds, they can fine-tune their nesting schedule to match local conditions season by season. Peregrines, arriving from wintering grounds much farther south, appear to rely more on internal seasonal cues that are harder to adjust on short notice.

A Surprising Twist: Warmer Summers, Fewer Young

One of the study's more unexpected findings was that warmer summer temperatures were linked to fewer surviving young in both species. Researchers hadn't predicted this result in a region known for being cold. One possible explanation is heat stress: young birds in the nest may struggle to regulate their body temperature during unusually warm spells, particularly in exposed nest sites with little shade.

Why This Matters for Arctic Conservation

Taken together, the findings suggest that climate change isn't just shifting when Arctic falcons breed. It may also be reshaping how successful that breeding is, in ways that differ depending on a species' life history. As Arctic warming continues to speed up, resident and migratory species may respond in increasingly different, and less predictable, ways.

The Peregrine Fund's long-term Gyrfalcon & Tundra Conservation Program has monitored Arctic raptors on Alaska's Seward Peninsula for more than a decade. It was one of many long-term efforts across the Arctic that made this study possible. The team's continued monitoring will help track how these patterns unfold in the years ahead.