Date of Award
Doctor of Philosophy (PhD)
Ecology & Evolutionary Biology
Daniel F. Doak
Anthropogenic disturbance is the leading cause of species extinctions (Vitousek 1997, Pimm and Raven 2000, Ewers and Didham 2006). Modern ecologists are given the task of determining how to predict and then mitigate species’ response to such disturbances. Species with larger niches, and more behaviorally flexible species, are predicted to better succeed in novel environments in the face of large scale habitat changes (Mayr 1965, Ehlrich 1989, Sol 2002, Shultz 2005). Foraging behavior can be a good descriptor of species’ niches, and the variation in these measures can be used to quantify behavioral flexibility (Sol 2002). My dissertation utilizes the interface between animal behavior data and broad-scale ecological patterns. I collected foraging behavior data (~7,300 independent foraging observations) across 74 of 75 Australian honeyeater (Meliphagidae) species to quantify niche size and position. I used functional dispersion (FDis) to quantify niche size. Related species foraged similarly, and foraging behavior showed significant phylogenetic signal. Generalists utilized a variety of resource acquisition strategies, whereas species with small niches were either highly nectarivorous or insectivorous. In order to determine if foraging niche size can be a predictor of extinction risk, I tested whether niche size was correlated with exposure or sensitivity to climate change. I did not find niche size to be a significant predictor of these risks as assessed by others. However, synergistic effects between small niche size and anthropogenic disturbance and climate change may put these species at an elevated risk of extinction. I also found a strong positive relationship between species that are highly nectarivorous and species that make attacks to the air for invertebrates. Nectarivorous species supplement their diets with protein, and it appears that these species make costly aerial attacks to acquire protein quickly. Geographic range size was not correlated with foraging niche size, but it was weakly correlated with niche position. Specifically, species that glean and hang from leaves in forests with high canopies were found to have smaller geographic range sizes. This is likely driven by the fact that such forests occur over a limited area in Australia, and occupy only remnants of their former geographic extent.
Wagner, Sarah Katherine, "Foraging Behavior, Behavioral Flexibility, and Range Size of Australian Honeyeaters (Meliphagidae)" (2015). Ecology & Evolutionary Biology Graduate Theses & Dissertations. 72.