Life on the Alaskan Tundra
Adam Eichenwald combines conservation biology and ecology to explore the trophic cascades that gyrfalcons have on the arctic tundra
Native Alaskans call it, “leaf-out”. Unlike the gradual growth of buds and leaves in the continental USA, the Alaskan tundra has an instantaneous moment where nearly every grass, shrub, and tree suddenly decides to sprout. And so spring begins, the sudden emergence of green supplants the bleak winter colors and perpetual darkness. The tundra transitions to a landscape awash with light, and in turn, life begins anew for many of its avian species. Here on this vast but vibrant landscape, Adam stood on the day after leaf-out, ready to shift his research methods from finding ptarmigans to investigating gyrfalcon nests.
With the help of YIBS funding, Adam Eichenwald (MESC 18’) was able to take a multi-plane, two day trek from New Haven to Nome. Adam first arrived to the cold snows of spring (in May!) but now leaf-out marked the beginning of more light, warmer temperatures, and undoubtedly, more pleasant weather. With this change of the seasons, Adam could shift his focus from ptarmigan (a ground-dwelling avian prey species the size of a chicken) to gyrfalcons (a dominant raptor), collectively studying the predator-prey relationship of gyrfalcons, ptarmigan, and their impacts on native tundra landscape.
Adam merged two different disciplines of science, ecosystem ecology and population ecology, to study trophic cascades. His original hypothesis proposed that gyrfalcons have a landscape of fear effect on prey species in the ecosystem. Almost like concentric circles within a bullseye (Figure 1), an individual gyrfalcon expends energy to hunt for food – flying to the outer circle takes a lot more energy than flying within the inner circles. With less time spent on the outer fringes of its habitat, prey species like ptarmigan might be more likely to be present in the outer circles and less likely to frequent areas close to gyrfalcon nests. And since ptarmigans eat the buds off willow trees, locations with higher abundances of ptarmigan may be more likely to have misshapen willow trees!
However, nature is never so simple, mitigating variables like topography, vegetation, climate, or interactions with other mesopredators might distort these relationships. So to test these theories, Adam had several research techniques in his bag of tricks. He would walk transects – 300 meters out from a point on the road – looking for ptarmigans. He would also walk these transects from gyrfalcon nesting sites, as well as collecting bones found in these falcon nests so that further DNA sampling could identify the species of ptarmigan eaten recently. Finally, counting leaf buds on surrounding vegetation eaten by ptarmigan helped explain the presence (or absence) of ptarmigan on the landscape.
Despite the wide open nature of the tundra, walking transects around the Seward peninsula could bring a number of surprises around any bend. Musk-ox, moose, and bear were just a few of the many species Adam encountered in his field work. He even documented the fear he put into a red fox one day when it nipped a little too close to his heel on a lonely Alaskan road. But this very nature of untouched wilderness and proximity to wildlife is what Adam really loves. Cooking fresh-caught salmon from the stream behind the cabin, basking beneath the midnight sun, or working with a research team to repel down to gyrfalcon nests, the ostensible arctic solitude is teeming with life to be discovered! Being out in such a vast landscape serves to remind us all that we’re just another link in that massive food web, YIBS is eager to fund researchers like Adam to help us shed light upon how it all connects.
Adam Eichenwald is a MEsc Candidate in Dr. Os Schmitz Lab at Yale University. He can be reached at firstname.lastname@example.org with research questions and inquiries.
Edited by Ben Zukowski, YIBS Science Communication Fellow