If you have a flock of goldfinches that have been hanging around all winter and summer, and notice females have all but disappeared, nesting is underway. When they are hungry, the female whistles to the nearby male in a call that sounds like teeteeteetee, and hubby shows up with some partially digested seeds which he kindly regurgitates for her. Perhaps it's because they are so attached to the thistles. As goldfinch fans know, these birds are love thistle seed. But they also make great use of thistle down which, mixed with some spider and caterpillar webs, make the bulk of the nest lining.
Goldfinches are easy to keep year round, even in our cold climate.
Just provide a thistle feeder and keep it loaded with niger, a kind of thistle seed that stores sell. This has us observing and trying to communicate with these amazing birds. Any information would be most appreciated. We have been using crow calls for years and have had at least three. They should be fairly easy to find at hunting supply stores, although they might be easier to locate in the Midwest and West where crow hunting is fairly common.