The Common Redpoll is a small songbird in the finch family. It is a Holarctic species, breeding in northern regions of Eurasia and North America and migrating further south in winter. Redpolls are boreal finches that breed in open coniferous forests across Canada and Alaska. They are irruptive winter visitors that sometimes stage massive southward migrations when seed crops fail on their breeding grounds. Despite being common in some regions, redpolls can actually be quite difficult to find in others depending on the year. So are Common Redpolls actually rare? Let’s take a closer look.
What is the range and population status of the Common Redpoll?
The Common Redpoll has an extremely large range across northern regions of North America, Europe, and Asia. Its global population is estimated at 160 million individual birds. Over half of the global population breeds in Canada and Alaska. In Europe, there are estimated to be 39-72 million pairs. In Asia, the population is estimated at 10-100 million pairs. So in terms of overall numbers, the Common Redpoll is clearly an abundant species. However, the fact that they are irruptive winter migrants means that their abundances can fluctuate dramatically between regions and between years. When food sources are plentiful in the north, they may not migrate very far south at all. But when boreal seed crops fail, they can stage massive southward migrations bringing large numbers into areas where they are rarely seen. So the Common Redpoll has a deceptive global distribution – they are common circumboreally but can be quite rare outside of their core breeding and wintering grounds.
What causes irruptions and winter movements of Common Redpolls?
Common Redpolls are irruptive winter migrants, which means their migration patterns are inconsistent and largely dependent on food supplies. Redpolls primarily eat seeds from conifers and birches. When seed crops are plentiful on their northern breeding grounds, the redpolls may not migrate very far south for the winter. But when conifer seed crops fail in the north, it can spark a mass southward migration known as an “irruption” into more southerly parts of their wintering range. The sporadic nature of these irruptions is what causes redpolls to be common in some years and places, but nearly absent in others. The timing and magnitude of these winter movements are quite variable both across years and regions. For example, during an irruption year, large numbers may move from northern Canada into the northern U.S. but relatively few make it further south into the central or eastern U.S. So food availability controls redpoll movements, and this explains why they can be so unpredictable in winter distributions.
Where are Common Redpolls most abundant?
During the breeding season, Common Redpolls are most abundant across Alaska, Canada, Scandinavia, and Russia where suitable open coniferous habitat exists. They strongly prefer spruce and birch forests, which provide food as well as nesting sites. The densest breeding populations occur in northern Manitoba, Ontario, Quebec, and Newfoundland and Labrador in Canada. In Alaska, they are widespread and common nesters.
Outside of the breeding season, winter habitat use depends on irruption magnitude and food supplies. In non-irruption years, most redpolls may stay in the northern parts of their breeding range year-round. In major irruption years, any areas with abundant birch or conifer seed crops can attract wintering flocks, sometimes as far south as northern U.S. states. But the most consistent and densest wintering populations tend to occur in Alberta, the Northwest Territories, Ontario, Quebec, New York, and Alaska where conifer forests predominate. So while nomadic in winter, the core of their population remains centered in northern boreal regions year-round.
In what parts of its range is the Common Redpoll rare?
The Common Redpoll is most likely to be rare along the southern periphery of its normal winter range. In mild winters, most birds may stay in the far north and only occasionally disperse south of Canada. For example, redpolls are rare and irregular winter visitors in many northern U.S. states such as Wisconsin, Michigan, Minnesota, and New England. Farther south into the central U.S. they are even rarer, being nearly absent most years in Iowa, Missouri, Illinois, and Ohio. Along the Pacific coast, they are similarly rare and sporadic in winter in Washington, Oregon, and California. At the extreme southern limits of their range such as the Rocky Mountains and southeastern U.S., redpolls are exceptionally rare vagrants even during irruptions. So while redpolls are common birds of the far north, they become increasingly rare and irregular farther south, especially outside of irruption years. The winter distributions simply cannot be predicted very far in advance due to their nomadic nature.
What are the habitat requirements and food sources for Common Redpolls?
Common Redpolls have very specific habitat needs and food preferences that drive both their breeding and wintering distributions:
Breeding Habitat
– Open coniferous forests dominated by spruce, tamarack, and birch trees. They rarely nest in pure stands of pine.
– Forest openings, edges, clearings, and early successional habitats with abundant young trees.
– Northern boreal transition zones between forest and tundra.
Winter Habitat
– Any habitat with abundant birch or conifer seed sources such as spruce, larch, hemlock, and pines.
– Weedy fields, roadsides, suburban backyards, and feeders stocked with nyger seed or small black oil sunflower.
Food Sources
– Seeds from conifers and birches make up over 90% of diet. Key foods are spruce, pine, larch, birch, alder, and hemlock seeds.
– In winter, they also eat buds, catkins, berries, and some insects to supplement diet.
– At bird feeders, they prefer nyger and small black oil sunflower seeds.
Redpolls are finicky birds that rely on very specific boreal habitats and seed types. This likely explains why their populations fluctuate so much and movements can be difficult to predict outside of their core range. Even within their normal winter range, it takes an abundant and widespread crop of birch and conifer seeds to attract and hold large numbers of redpolls. Without access to these key food sources, redpolls simply won’t stay long even when they do irrupt southward. Their specialized ecology is key to understanding redpoll rarity and irruptive behavior.
How do populations and distributions of Common Redpolls vary between years?
There is dramatic annual variation in Common Redpoll numbers and distribution patterns throughout their range:
Breeding Grounds
– Breeding densities vary annually across the boreal forest in response to food supplies and nesting conditions.
– In peak years, densities can reach 300-400 pairs per square kilometer locally.
– In poor habitat or food years, breeding densities may be just a few pairs per square kilometer.
– Nest success also varies annually – inclement weather can reduce reproductive output.
Wintering Grounds
– In non-irruption years, most redpolls overwinter in Alaska and Canada with limited southward movement.
– During irruptions, large flocks appear farther south in the northern U.S. or even the Atlantic coast.
– The frequency, periodicity, and magnitude of irruptions are irregular and impossible to predict.
– Migrant numbers vary dramatically between winters in a given southern region.
Causes of Annual Variation
– Fluctuations in boreal seed crops, especially conifers, drive breeding success and winter movements.
– Weather conditions like drought, early frost, snow cover further impact food availability.
– Predation pressure, nest parasitism, competition, and disease can reduce breeding output.
– Weather severity may directly control overwinter survival and reproductive success.
So in summary, redpoll numbers and distributions are highly variable and directly tied to food supplies and weather. Without abundant boreal seed crops, populations can decline and southern irruptions fail to materialize. These small finches are adapted to a harsh and fluctuating northern environment.
What are the trends in Common Redpoll populations over the long term?
Despite short-term fluctuations, the overall population trend for Common Redpolls is stable and possibly increasing:
Breeding Bird Survey Trends
– Data from 1966-2019 shows a survey-wide increase of 0.81% per year.
– Trends are significantly positive in western and eastern boreal Canada.
– Alaska shows a non-significant increase of 0.36% per year.
– Evidence points to a slow, long-term population expansion.
Christmas Bird Count Trends
– Redpolls show a significant national increase of 2.1% per year from 1966-2015.
– All regions show increases, especially the northern U.S. and boreal Canada.
– Irruptive spikes are visible but the baseline is still increasing.
Partners in Flight Estimates
– Their boreal population estimate is 260 million redpolls, confirming great abundance.
– The overall population objective is “maintenance” given their common status.
Boreal Habitat Trends
– Climate change may slowly increase available spruce-birch boreal habitat over time.
– Natural disturbance patterns continue to maintain suitable habitat.
– Anthropogenic threats are still localized compared to the vast boreal forests.
So while irruptive behavior makes redpolls seem ephemeral, when viewed long-term their populations appear stable to increasing in the core of their boreal range. The outlook seems positive for this tough northern finch.
Conclusion
In conclusion, the Common Redpoll is an abundant boreal songbird but remains rare and irruptive south of Canada. Their populations fluctuate dramatically between years and regions due to their dependence on boreal seed crops. While their numbers crash periodically, the long-term trend is stable to increasing as boreal forests persist. So redpolls exemplify how a species can be globally numerous while still being a rare and irregular visitor along the southern edge of its range. Their unique irruptive nature adds an element of mystery and excitement when these gregarious northern finches occasionally stage a winter invasion. So while not rare in their Arctic and subarctic strongholds, redpolls are certainly still a prize sighting for birders when they do make a rare southerly appearance in irregular winters. Their unpredictability makes them a special winter treat across much of North America.
Region | Breeding Season Abundance | Non-Breeding Season Abundance |
---|---|---|
Alaska and Northern Canada | Abundant | Common to abundant |
Boreal Forests | Common | Uncommon to common |
Northern U.S. States | Rare breeder | Rare to uncommon |
Central and Eastern U.S. | Non-breeder | Very rare |
Western Mountains | Non-breeder | Very rare |
This table summarizes the abundance and status of the Common Redpoll across different regions of North America during the breeding and non-breeding seasons.