Camera Critters: Hoary Redpoll

Frequently during the winter here in Minnesota, as well as many other northern states, we experience bird irruptions. An irruption is when a species of bird heads south in greater numbers then usual and floods the area. Most the time the cause of the irruption is a lack of food source in the typical winter range. Irruptions are often confused with invasions. An invasion is when a species moves into an area where it is not typically found.

This past year we had an irruption of several different types of northern finch. These included white-winged crossbills, pine siskins and redpolls. Most of these species could be found south of the Twin Cities this winter and in some cases I read reports about sightings in Iowa or even further south.
As is typical most of the redpolls which we saw down in the southern part of the state during the irruption were common redpoll however if you looked at the groups of redpolls carefully you might get lucky to spot a hoary redpoll, although all of the ones that I spotted were in the northern portion of the state. These pictures where all taken in January up at the Sax Zim Bog area.

Common redpolls are pretty hardy for such a small bird. They have to be, since they spend most of their lives up in Canada, but they have nothing on the hoary redpoll. Hoarys spend the breeding months up on the northern arctic coast of Canada and Alaska, further north then many of the common redpoll, and they winter mainly in Canada, with occasional forays into the northern United States.
Since hoary redpoll are often mixed in with common redpoll they are often difficult to Identify. The first thing to look for is a bird that looks more pale then the other redpolls. Since common redpoll can often look pale, especially depending on things like the light and the angle of view, it is necessary to look a little more closely in order to determine if it is a hoary or a common. The next thing to look at is the bill. Hoary redpoll have a smaller more conical bill where the common redpoll has a longer more pointed bill. If you compare the bill on the bird pictured above, which is a common redpoll, to that of the one above it you should be able to see the difference.

However it is often difficult to see and judge the bill size on small birds that are moving around, when you are in the field. So there are other things that you can look for when trying to decide if a bird is a hoary or a common. If you look at the common redpoll photo again you will notice that it has significant black streaking running down its sides. In the picture above you will notice that hoary redpoll have very little streaking and what they do have is very fine.
If you are really lucky you will get mooned by the bird, which is one of the best ways to distinguish between the two types. The common redpoll typically has black markings on the undetail coverts which it can be identified by. The hoary usually has little to no marking on the coverts. Hoary redpolls also usually have a white rump compared to the common redpoll which has a streaked rump.