Ian,

I have observed Elegant Terns doing the same process. I have photographed Elegant Terns at Marin Headlands in California where the young that are traveling with the adults are begging for food despite the fact that they are many miles from where they bred. http://birdcentral.net/etern.htm

Reminds me of my relationship with my parents.

Jim Rosso
jlrosso at aol.com