Monday, 20 April 2015

B.O.T.D. Hoary Redpoll

Hoary Redpoll (Acanthis hornemanni)

Common Redpolls and Hoary Redpoll can be confusing to differentiate because they look alike, share similar ranges and have similar songs and calls. The Hoary Redpoll is almost always seen with flocks of Common Redpolls and is generally paler and less streaked, with a stubbier bill. Some Hoary Redpolls are nearly impossible to differentiate from Commons, however, because of individual  variation within both species and some overlap in identifying features. Both redpoll species are remote northern nesters and "predictable unpredictable" winter visitors to southern Canada. Like many finches, they can be abundant one year and almost absent the next. In the south, they tend to be more abundant every second winter, reflecting cyclic lows and highs in seed availability in their normal (northern) range. Things were much simpler when the two redpolls were considered a single species.

Redpolls are widely  adapted to life in the cold. They have a high level of food intake, in part because of a special storage pouch in the esophagus (the esophageal diverticulum), which allows them to carry large quantities of energy-rich seeds.

Lone Pine Publications: Birds of Canada