On their breeding grounds Hoary Redpolls, like Common Redpolls, hang out in patches of scrubby birch and willow. In winter, Hoary Redpolls are occasionally seen with flocks of Common Redpolls and I always scan flocks to look for the scarcer Hoary. The two Redpolls look very similar to each other. The Hoary Redpoll is paler overall, whiter on the chest and displaying little or no streaking on flanks. Hoarys appear bulkier, probably due to greater feather mass and fluffier plumage. Their bill is shorter and stubbier and surrounded by denser feathering at base so that it appears even smaller.
This winter the Hoarys have been reported more frequently than in recent past winters. I was lucky to have one pose for me yesterday just for a second. Below is the Hoary and the Common, both females. You can see the difference when they are side by side.
|Hoary Redpoll (Acanthis hornemanni)|
|Common Redpoll (Acanthis flammea)|