A Character Index for Redpoll identification

[edited 12 and 14 Jan, 2008, adding comments about the index] I’ve been thinking about redpolls more, and had another, more careful, look at Troy’s 1985 paper, which is filled with interesting observations and some serious “food for thought”. First of all, Troy identified redpoll specimens using a character index, which is a well-established method … Continue reading A Character Index for Redpoll identification