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Henderson, Michael – Effect of nest-site characteristics on Gyrfalcon reproduction in a changing landscape

Michael Henderson in Alaska - drop off at remote nest location (by helicopter)

Drop off at remote nest location

The most prominent issue facing Arctic specialists, including Gyrfalcons (Falco rusticolus), is the uncertainties of climate change, making the future of populations hard to determine. This is in part because the northern latitudes are seeing the most dramatic changing including an increase in shrubs, changes in the timing of snow melt, temperatures, and the intensity of precipitation. These may have indirect implications on Gyrfalcons by shifting prey availability or direct implications by exposing birds to harsh weather, particularly nestlings that are not capable of evading the threat on their own. Gyrfalcons, being a top avian predator, can act as a sentinel that reveals the health of the ecosystem it calls home.

Camera install

Camera install

When faced with a dangerous stimulus or a changing environment, a bird can respond in two different ways. First, they can respond physiologically by increasing the secretion of stress hormones (corticosterone), which encourages immediate survival but has been shown to influence subsequent fitness and survival.  Another physiological cost could also be a reduction in body condition due to negative stimuli. The second way a bird can respond to their environment is behaviorally. Adults may choose a nest that has protective properties, such as a large over hang, to protect nestlings from inclement weather. Additionally, an adult can invest more time and energy into caring for young, which can have costs to subsequent reproduction efforts.

Gyrfalcon chicks

Gyrfalcon chicks

I hypothesize that there are certain nest-site characteristics that can act as a buffer against the negative impacts of weather. Evidence for my hypothesis will be higher productivity, a more consistent nest temperature, reduced parental investment, lower levels of stress, and high body condition for nestlings reared in nests that have protective qualities, compared to nests that are exposed. This research will help inform predictive models aimed to project population health of Gyrfalcon populations and could have implications for mitigation efforts in the form of protective structures being added to vulnerable nests and areas of Gyrfalcon range.