The recording below was from a small flock of migrating Redwing as they flew overhead this morning. The middle call in the group of three on the sonogram below, is distinctly different to the normal Redwing 'seeep' flight call from the two birds around it, and is more like a Waxwing like thin 'trill'. Not a call i've noticed or heard from Redwing before. The Redwing making the 'trill' call can be heard again shortly after, but this time more distantly as the flock heads away from me.
Redwing flight calls sonogram 14/10/10Redwing (Flight Calls from flock) Lutley Wedge 14/10/10 by Lutley Birder