Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Bluebirds are found in
vast green fields
North America, Europe, and Asia. (Note: Bluebirds are actually found primarily in North America, but the question asks for all locations.)