Landscape scale thermoregulatory costs from sublethal exposure to Deep Water Horizon oil in the double-crested cormorant
2020
Dorr, Brian S. | Mathewson, Paul D. | Hanson-Dorr, Katie C. | Healy, Katherine A. | Horak, Katherine E. | Porter, Warren
Toxic effects of heavy oiling to wildlife are well known from oil spills, although sublethal oil exposure effects are poorly understood. We used Niche Mapper™, to compute spatially and temporally specific energetic and behavioral impacts of repeated sublethal oil exposure to double-crested cormorants (Phalacrocorax auritus). During winter (October-March) cormorants exposed to 13 g, 39 g, and 65-78 g of oil, had on average a 31%, 59%, and 76% predicted increase in total resting energetic requirements (RMR) compared to unoiled birds, respectively. Increased RMR resulted in a mean (±SD) predicted increase in time spent foraging of 36 (±13) min·d⁻¹. During the breeding season (April-September), cormorants had on average a 29%, 57% and 73% increase in total RMR and the mean predicted increase in time spent foraging was 131 (±49) min·d⁻¹. Thermoregulatory effects of sublethal oil exposure may cause greater impacts to bird populations than is currently understood.
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