Foraging behaviour and flight dynamics of rhinoceros auklets (Cerorhinca monocerata) experimentally dosed with diluted bitumen

Seabirds have long been used as "bioindicator" species in eco-toxicological monitoring, but most studies related to oil pollution have involved conventional crude oils. The majority of current Canada's oil production involves highly viscous oil sands bitumen, which must be diluted in order to enable transport through pipeline (i.e. "dilbit") but virtually nothing is known about dilbit toxicity in birds. I used GPS-accelerometers in free-living Rhinoceros Auklets (Cerorhinca monocerata) combined with internal and external dilbit dosing to investigate effects on reproduction, foraging and diving behaviour. There was no effect of treatment on retrieval rates, mass change of adults during deployment, or chick mass gain. Chicks raised by externally-dosed birds had reduced wing growth at day 25 compared to internally-dosed or control birds. There was no difference in trip length in relation to treatment. Within their daily time-activity budget, internal-dosed birds spent less time diving and more time swimming compared to external-dosed birds, with control birds being intermediate. We used accelerometers to calculate wing-beat frequency (WBF), wing-beat amplitude (WBA), overall dynamic body acceleration (ODBA) and pitch; for each of these metrics, there was substantial overlap in values between treatments. I discuss why our dilbit treatment had few significant effects and suggest future directions for research on dilbit.