"Only a couple things can happen," he continued. "They can arrive and if there's lots of oil still in place and they land in it and get covered in oil they're likely not to fly off again. If they land and don't find food, maybe they'll move on--that's probably the best-case scenario. If they land and find food that's been coated in oil or other toxicants and ingest it they're likely to get sick or impact their survival over the winter and maybe even reproductive cabability. What happens if the large portion of the population that comes down here to winter dies?"