What Is A "Superflight?"
Where Did These Invaders Come From?
Was the 1997-98 Irruption More Significant for Some Winter
Finches Than Others? |
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Every winter, birders across the continent hope the season will
bring an influx of finches from the north, and the
1997-98 winter season presented us with perhaps the most outstanding
finch year in recent history. Starting in mid-September, these species--Pine Grosbeak, Purple Finch,
Red Crossbill, White-winged Crossbill, Common Redpoll, Hoary Redpoll, Pine Siskin, and Evening Grosbeak
as well as the Red-breasted Nuthatch--began moving south from their
typical northern winter ranges in what is called an "irruption." These irruptions are
thought to be associated with broad-scale changes in food seed supplies in their
northern range, possibly after a particularly successful breeding season.
The 1997-98 irruption may well have been the largest in a decade. |