Pine Siskin
by Mim White
Title
Pine Siskin
Artist
Mim White
Medium
Photograph
Description
Every couple of years, Pine Siskins make unpredictable movements called irruptions into southern and eastern North America. Though they�re erratic, these movements may not be entirely random. Banding data suggest that some birds may fly west-east across the continent while others move north-south. For more, see this post from Project FeederWatch.
Following a large irruptive winter flight, some individuals may stay near a dependable food source and breed far south of the normal breeding range.
Bird-banding projects are invaluable for tracking migrating birds, even though few bands are ever recovered for small birds like siskins. Nearly 675,000 Pine Siskins were banded between 1960 and 2011; fewer than 2,000 were later found. By contrast, about one-quarter of the nearly 5,000,000 geese banded in the same period were recovered.
Pine Siskins get through cold nights by ramping up their metabolic rates�typically 40% higher than a �normal� songbird of their size. When temperatures plunge as low as �70�C (�94�F), they can accelerate that rate up to five times normal for several hours. They also put on half again as much winter fat as their Common Redpoll and American Goldfinch relatives.
Pine Siskins protect their eggs from cold damage, too. The nest is highly insulated, and the female remains on the nest continuously, fed by the male throughout brooding.
Pine Siskins can temporarily store seeds totaling as much as 10% of their body mass in a part of their esophagus called the crop. The energy in that amount of food could get them through 5�6 nighttime hours of subzero temperatures.
Uploaded
January 19th, 2016
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