Redpoll identification

With a cold NNW wind blowing today and a high of -11°C / 12°F (!), wind chill factors plummeted to unbearable depths. Raptor migration also reached its absolute nadir - zero migrants recorded - so let's turn to something more rewarding: redpoll identification.

The problem is well-known: two species, Common and Hoary Redpoll, which are very similar in appearance. Adult males are distinctive, but great care is needed to separate females and immatures of these two species. Overall, Hoaries are paler, with shorter bills, pale rumps (vs. streaked in Common), less streaking on undertail coverts, fainter flank streaking, frosty streaking on the back with pale rear scapulars, and more white on secondaries and coverts.

The photo at the top shows two Common Redpolls in the upper right, with a pale bird on the left that's a candidate for Hoary.

Here is a larger image of the paler bird. (Clicking on these photos will blow them up even further.) Note how pale overall this bird is, with pale rear scapulars, a pale face, and broad white edges on the greater coverts.

The very top photo I cropped to show this bird with some obvious Common Redpolls for comparison. Below is another crop of the same photo, showing what I think are two more candidates for Hoary Redpoll (lower center). The angle on these birds, however, makes their case a harder one to make.

Compare these two birds with the two lower birds on the outsides, and note how much paler they are.

Here's another pale bird, probably one of the three.

Here is the same photo, a little enlarged, with a Common Redpoll in the top left for comparison.

Note that paleness combined with a round, fluffy appearance is not sufficient for calling a bird a Hoary. This is a rather pale Common Redpoll with a round, thick-necked posture suggesting Hoary. Note the longer bill, however, and the absence of white tips on the lower mantle (scapulars). Also, the head is browner than on the three paler redpolls.