Please see the Nature article I linked to and note that every instance of "composition" refers to change in the composition. Some examples: - "bird community c

Please see the Nature article I linked to and note that every instance of "composition" refers to change in the composition. Some examples: - "bird community composition also reacting promptly to the introduction and removal of feeding stations" - "food resources provided by the British public have altered the composition" - "feeding practices appear to have contributed significantly to the changing composition" - "the composition of bird communities exploiting garden bird food has changed" - "Changes in community composition" The paper also contains 20+ uses of "effect" as a noun. Affected is clearly the intended word. The reporter made a mistake. To "effect something" is to "cause it to occur" and in this case, bird feeding hasn't caused population composition to occur, but rather has changed the existing population composition. BTW, I sent a DM to the reporter. I'll report back if he replies.