[Tweeters] Tweeters] mtn/urban birds

[Michael Price]

Hi tweets

Fascinating thread. Dennis mentions Red-breasted Sapsucker's occasional
vertical winter movement from mountain to sea level in winter. The pattern
in Vancouver BC is that this happens in severe winters but hardly ever in
mild ones. As was explained to me by the late, irreplaceable Kevin Bell,
the sapsuckers move down to sea level when the cold is sustained long
enough to reach the roots to freeze the movement of sap in the trees. So
that's why there's a two- or three day interval between the arrival of a
sustained Polar regime and the sapsuckers heading downhill. If the Arctic
air lasts long enough, you'll get an influx of RBSA at sea level.


Been around long enough to remember when you could still find some of our
Sooty Grouse at sea level in North and West Vancouver BC. These guys bucked
the trend by going up to the higher altitudes in winter where, like
ptarmigan, they can stand atop the deep snow to feed on spruce buds. Which
makes them taste like turpentine--what a friend told me. Gah.

best, m
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