Bridger Creel
a bird’s eye view: using tree swallows (tachycineta bicolor) to assess the effects of aquatic metal contamination on riparian insectivores in the upper clark fork river superfund site.
Bird populations are declining worldwide, with insectivorous populations shrinking at a faster rate than other groups. Many avian insectivores rely heavily upon emergent aquatic insects that are more nutritious than terrestrial prey types due to the presence of essential highly unsaturated fatty acids. However, this reliance on aquatic prey allows perturbations in aquatic ecosystems to propagate to riparian avian insectivores. In systems impaired by metal contamination (e.g., heavily mined areas), birds can be exposed to aquatic metals via trophic transfer from aquatic insects or metals can lead to a loss of important aquatic prey if insects succumb to metal toxicity before or during metamorphosis. It is simple to predict the effects of a single metal on this aquatic-terrestrial trophic linkage, but ecosystems impaired by mine-waste contamination are commonly afflicted by elevated environmental concentrations of a mixture of many metals. Thus, when a mixture of metals is present in the aquatic ecosystem, it is difficult to predict whether insectivorous riparian songbirds will primarily be affected by metal exposure through their prey, or the loss of nutritionally important aquatic prey. The Upper Clark Fork River (UCFR) in Western Montana represents the largest Superfund site complex in the United States due to aquatic mine-waste contamination in and along the river forming a gradient of metal concentration (primarily Pb, As, Se, Zn, Cu, and Cd). Tree swallows (Tachycineta bicolor) are an aerial insectivore that relies very heavily on aquatic prey and have been used extensively as a model system to study songbird response to perturbation. In the UCFR, we are assessing Tree swallow response to aquatic metal contamination by measuring differences in blood metal concentration, dietary reliance on aquatic prey, breeding success, and two physiological bioindicators of stress across nine sites. Investigating patterns of association between songbird metal accumulation, diet, and tree swallow health/fitness will provide a more holistic understanding of the ecological impacts of mining contamination on riparian consumers.
Bridger Creel received their B.Sc. in Ecology and Evolution from the University of Montana in 2019. In undergrad they gained broad experience in ecology, studying photosynthetic bacteria to African wild dogs. After graduating, they spent several years conducting avian research with The University of Montana Bird Ecology Lab (UMBEL) and Raptor View Research Institute and worked with The Clark Fork Watershed Education Program to instruct Missoula area elementary students on the impacts of historic mining practices. These experiences sparked their suite of interests in environmental toxicology, and food web ecology and stress physiology as they relate to avian conservation. This has led them pursue a PhD in collaboration with UMBEL and Drs. Creagh Breuner Ben Colman, studying how metals from mining contamination accumulate in the riparian food web and impact songbirds. When not studying birds, Bridger takes to the mountains and valleys surrounding Missoula to ski, bike, skateboard, and look for more birds.