the topic is usually the first sentence, so it is:
Based on a rigorous review by a team of U.S. Fish and Wildlife Service biologists of previously released preliminary data, the Service has compiled an expanded report of the birds rescued and collected during the response to the Deepwater Horizon oil spill.
Explanation:
have a good day and don't stress out too much its only school (:
The main idea of the passage is "Federal field biologists patrol coastal waters and marshes daily searching for wildlife in distress, including thousands of coastal shorebirds, wading birds and migratory species, so that way they can preserve and aid them."
