As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FUMES THROUGHOUT AIRCRAFT IMMEDIATELY AFTER LIFTOFF. AIR RETURN TO IAH. REF L/P 8947603, PERFORMED MM TASK 05-51-26-800-801-C1 AND REPLACED RECIRCULATION AIR FILTERS REF 21-25-01-000-801. NO FAULTS NOTED. - FOUND BIRD INGESTION IN NR 1 ENG