So, I have Red Crossbills in my neighborhood most of the year, flying here, flying there, always 'chewp-ing'. Until today, they all sounded like one type. I've not spent enough time figuring out one type from another but today it sounded like two different types together calling at the same time. Along with about 10 that were calling the usual 'chewp', there were several that were trailing the group that sounded more like 'twit', almost on an upswing. I can't say whether or not there were two types of Crossbills today, but to my ears it definitely seemed so.
Cheers,
Amy SchillingerRenton, WAschillingera at hotmail.com