Date: 10/1/19 11:13 am
From: Lars Norgren <larspernorgren...>
Subject: [obol] Provenance of passerine migrants
Many common, widespread songbird species both nest in western Oregon
and pass through here en route to more distant breeding and wintering
grounds. The details of various populations remain unknown, and our
assumptions unsupported. I suspect that Red-eyed Vireos, Hermit Thrushes,
and Varied Thrushes being detected now are not local breeders, but arrivals
from hundreds of miles to our north and east. The paucity of passerine
detections in the Coast Range is of course an artifact of low observer
effort. But the effort is to a large extent limited because experience has
demonstrated that effort will not be rewarded . Heat units are low here (I
'm sitting in the silent D-firs and alders right now) and insects few. I
left sunny skies and (rising) temperatures in the sixties at Tillamook on
Sunday to drive through drizzle and sub-fifties in the Mountains to the
east. Willows on the banks of the Willamette or shores of Yaquina Bay offer
a great opportunity for migrants to put on fat.

 
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