Citizen science reveals widespread impacts on birds from the deepwater horizon oil spill

Northern Gulf of Mexico coastal habitats support millions of birds during at least one part of their life cycle making it a globally recognized area of conservation importance. On 20 April 2010, the Deepwater Horizon oil rig exploded about 65 kilometers from the southeast coast of Louisiana, spewing an estimated 4.9 million barrels of crude oil into the northern Gulf of Mexico. Currents brought this oil to shore, impacting 2,580 km of shoreline and placing dozens of waterbird species at high risk of exposure. We trained and mobilized citizen scientists to assess the frequency and extent of oiling on coastal waterbirds from Louisiana to the Florida panhandle. We combined the dataset resulting from these citizen science surveys with additional observations submitted to eBird. Dozens of volunteers assessed 60,403 birds in oil-impacted and non-impacted sites between May and November 2010. Among 33 waterbird species, including species of high conservation concern such as Least Tern, Wilson‘s Plover, and Reddish Egret, 982 individuals showed evidence of oiling. Spatial and temporal patterns of oiling rates corresponded with the spread of oil and subsequent capping of the well with the highest rates of oiling seen in southeastern Louisiana in June and July. During this period, 17% of wading birds were found with oil, higher than other foraging guilds. In addition to providing an independent assessment of oiling frequencies during the Deepwater Horizon disaster, this study highlights how citizen scientists can mobilize quickly to collect valuable data at large spatial scales.