We also continue to have people joining up to study birds and learn how to ring. There's lots to learn in the BTO training process; here's a very small example from a session last Sunday.
The Goldfinch opposite - yellow on wing & the head pattern are key to identification - can be sexed as a male. How? Male Goldfinches can be distinguished by a larger red mask that extends just behind the eye. In females, the red area is smaller.