We have a corncob holder that we use in winter to feed the birds.

Starting in spring I shift it to holding nesting fluff. This year I found some nice natural cotton that is made just for this purpose, and the goldfinches have started to take it yesterday.

First photo is a newly moulted male gathering some.

Second photo is a female doing the same.

The dark stuff below is alpaca fur, the lighter color has been taken but the darker is less popular.
I bought both types of fluff this year on Ebay.

I took both photos thru my wavy window glass.

Since the finches have their new breeding feathers, there is lots of action around the house now of them flying around and making finchey sounds.

Cornell University (the same as where the Red Tailed Hawks cam resides) is a great place to learn about birds... they even have recordings of their songs and calls.
this link is of the Goldfinches:

.