Carduelis pinus

After taking a break from visiting the back yard, Pine Siskins have been around again in the last few days. I have been surprised at how deep yellow the feathers are for many of the birds we see. It's normal to see the yellow in the wing bars and tail feathers, but I have not noticed yellow in the general body to the extent we see them. Are these young? Males? I need to do some research.
 
Note added on 8/16/2010: Apparently there is a fairly rare form of the Pine Siskin (1% of them) called a "Green-Morph". Now I don't see anything that looks like green here, just a yellow bird. But if you look around at other web sites, check out what people are calling a "Green-morph" Pine Siskin.