Populations of this bird of the Boreal and Taiga regions are poorly monitored by existing surveys. The best source of data for status assessment come from the Christmas Bird Count (CBC), which covers a good portion of the wintering range in southern Canada and the United States. However, the Common Redpoll is well known for its large biannual irruptions prompted by seed failure at high latitudes causing the birds to move south in search of food (Knox and Lowther 2000a). These biannual irruptions are apparent in the large fluctuations seen in the CBC annual index graphs (see table below). CBC results suggest a large increase in population but have poor precision and may be dominated by birds that breed in Alaska, the core of the North American breeding range for the species. Considering the ongoing wide biannual irruptions in Common Redpoll, these CBC results may reflect shifts in population distribution rather than changes in the numbers of individuals. With these caveats in mind, the Common Redpoll is assessed as having shown a large increase in numbers in Canada since 1970 but the reliability of this assessment is low. The Common Redpoll is currently considered to be at an acceptable level relative to its national population goal (see Canada graph below).
Additional information on: Christmas Bird Count (CBC)
