Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences


Breeding Parameters, Climate Change, Isotopic Niche, Stable Isotopes


Oliver P Love


H Grant Gilchrist




Resource limitation drives fitness-related decisions and constrains the ability of organisms to invest in energetically demanding life history stages. Environmental factors (e.g., temperature) play an important role in affecting resource availability and quality which can downstream effect the ability of individuals to invest in energetically demanding life history stages, including reproduction. Human-induced climate change is generating increasingly variable environmental conditions, impacting the abundance and distribution of prey items and therefore the ability of individuals to successfully reproduce, and these effects are especially pronounced in the Arctic. However, it is currently unknown whether Arctic organisms possess the ability to adjust foraging decisions and prey selection to overcome newly emerging environmental constraints. Quantifying stable isotopes in the tissues of consumers provides a minimally invasive method of inferring foraging niche; however, has yet to be validated as a method of predicting population-level resiliency to climate change. Seabirds are a useful system to test these linkages in because they are wide-ranging, predominantly oceanic-based group, reliant on marine-based resources and they are often widely distributed across polar regions. Using common eiders (Somateria mollissima), an Arctic diving seabird, as a model organism, this thesis examines the linkages between environmental variation, isotopic variation in foraging niche, and breeding parameters, as a means of predicting the resiliency of Arctic seabirds to the effects of climate change. Using a long term data set from a focal breeding colony, I found significant inter-annual and inter-breeding stage variation in isotopes and isotopic niche. Although environmental cues only weakly predicted variation in isotopic niche, variation in isotopic niche was a key predictor of breeding probability. Given that variation in isotopic niche has fitness-related impacts, I then took a species-wide approach to assess inter-colony variation in isotopic niche by sampling 8 breeding colonies across the distribution of eiders. While common eiders are a generalist species overall, individual colonies had significantly different foraging strategies and levels of generalization. Taken together, these results suggest that common eiders are likely to be resilient in the face of climate change, but some colonies may be more at risk from the ongoing effects of climate change. This thesis provides the first steps towards developing a minimally invasive method for foraging flexibility as a means of assessing the resiliency of Arctic seabirds to climate change.