Arctic shrubs have expanded dramatically in northern Alaska over the past century, resulting in significant changes to albedo, ecosystem function, and wildlife habitat. In the early spring, tens of thousands of ptarmigan migrate from wintering areas south of the Brooks Range to the northern foothills and Arctic Coastal Plain, where they form large aggregations in tall shrub patches. At this time, ptarmigan are greatly influenced by the availability of tall willows, which offer both food and protection from predators. As shrub expansion continues to increase the height and abundance of willows, ptarmigan should experience an increase in winter and spring habitat availability.
Whilst potentially benefiting from shrub expansion, ptarmigan play an active role in altering the architecture and productivity of arctic shrubs through heavily browsing them. A trophic feedback loop may result, where selective browsing by ptarmigan curtails the expansion of preferred willows, while indirectly enhancing the expansion of other, competing shrubs. For Katie Christie’s Ph.D. research, she investigates the spatial extent and magnitude of browsing by ptarmigan in the arctic, and their influence on the architecture and productivity of arctic willows. I also conduct aerial surveys over a mosaic of riparian and upland habitat types to quantify the spring distribution and habitat associations of ptarmigan in northeastern Alaska.
In the high arctic of North America, climate change is already having dramatic effects on landscapes and herbivores. Ptarmigan may serve as an ecosystem “indicator” species, providing a glimpse at what life may look like in a changing arctic world.