Narrative:

Just after liftoff; we ingested a large hawk in our number 1 engine. The engine continued running; but a vibration of 2.4 was noted on the vibration gage. We elected to declare an emergency and return for an overweight landing. Aside from the aforementioned; it was a totally routine flight.

Google
 

Original NASA ASRS Text

Title: A B737-800 flight crew declared an emergency and returned to their departure airport after ingesting a large bird in the left engine on initial climbout.

Narrative: Just after liftoff; we ingested a large hawk in our number 1 engine. The engine continued running; but a vibration of 2.4 was noted on the vibration gage. We elected to declare an emergency and return for an overweight landing. Aside from the aforementioned; it was a totally routine flight.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.