Surprisingly a Seagull can stay in flight for 6 months at a time without needing to land and they can also sleep while floating and gliding in the air.
That's amazing that they can sleep in the air and continue flying and gliding for 6 months but some seagulls may land sooner if they get tired.
Baby seagulls can begin to fly as early as 6 to 8 weeks old although they might not fly non stop until they get a bit older.
I've seen some seagulls take off on flight and then land 5 to 10 minutes later if they were going a short distance but researches have found that the seagull if needed can stay in flight for the 6 months at a time before landing.