Tweeters:

How much variation is there in the size of Pine Siskins?

I had two on a feeder at the same time, but one was 50 per cent larger than
the other. The smaller was more of a classic siskin: typical size, trim,
yellow on edges of feathers in wings and sort of on the side of rump, deeply
notched tail, beak not as thick as a finch, very finely streaked head. The
much larger siskin also had the yellow, the deeply notched tail and the same
beak, but was much more plump and heavily streaked on the back of the head as
well as the back itself. Both were sitting with their backs at not quite a 45
degree angle to me, on either side of a tube feeder, and I had a good long
opportunity to look at them. The size difference did not appear to be caused
by the feathers on one being puffed up.

The size difference was so striking I first thought the larger bird had to be
some other species, especially because this fall I have seen only an
occasional siskin at the feeder, always by him/herself.

Eric Stahlfeld
StahfeldE at aol.com