How do you know it's only once a month? Are you with him and observing him 24/7? How long has he been doing this? What, exactly, does he do with his foot that makes you believe he is putting it in his beak to stop the tongue movement? Have you looked inside his beak? Has he been to the vet in the last 6 months? Does he pluck? What is his diet, exactly? Is he alone in his cage? Does he chew on the bars? Is the cage made out of a safe material with no chips? I am not trying to be difficult or give you a hard time, mind you, I am just trying to get as much information as I can.