Date: 6/5/19 8:15 pm
From: David Bailey <davidcbaileyoregon...>
Subject: [obol] Describing migrant shorebirds, was: Late Coos Shorebirds
Descriptors for migrant birds that inform the reader as to whether the
individual(s) are migrating (north south, or otherwise) are problematic to
assign, especially at the extreme date ranges for known migratory periods
of the population observed. After thinking on this, I would call a
Red-necked Phalarope seen suddenly on 18 or 20 June in Coos simply a late
Spring bird (assuming it was prior to solstice). We can't know without more
data on that individual whether it has just arrived in Oregon from the
north or even from the south. It could have been over-summering somewhere
nearby, who knows? As for calling birds in July "early Fall" birds, why not
just "early summer" birds if not showing evidential behavior suggestive of
a directional movement? If memory serves, I have learned that a significant
number of second-year shorebirds stay all that year-round on their
wintering grounds; some migrate north to a latitude somewhere short of the
population's breeding range and then stage for the summer before heading
back south.

Certainly hypotheses of what behavior the birds we encounter are engaged in
are important, but when describing the birds movement there is no inherent
need to give a concrete descriptor when the evidence for such behavior is
lacking or equivocal.

Please discuss.

David

David C. Bailey
Seaside, Oregon

On Wed, Jun 5, 2019, 17:34 Tim Rodenkirk <timrodenkirk...> wrote:

> Last Friday the 31st there was a large flock of 37 Whimbrel and one
> Marbled Godwit at Bandon Marsh. On the 2nd Richard and Margaret Alcorn had
> 45 Whimbrel and the one godwit still around. Whimbrel are sometime around
> all June so hard to say when the latest spring date is. The latest spring
> date for godwit in Coos is 18 June and earliest “fall” arrival 5 Jul.
>
> Also on the 2nd Daniel Farrar had a late Red Knot at the mouth of Tenmile
> Creek in NW Coos. The latest spring record for Coos was 4 June by Daniel at
> the same location in 2014.
>
> Yesterday, the 4th, there were five Red-necked Phalarope at the old
> Weyerhaeuser settling pond site on N Spit of Coos Bay. The latest spring
> date I know of for this species is 15 June and was a bird that had been
> around for over a week. The earliest arrival for this species is 24 June.
> However, in 2015 there were singles on 18 and 20th June- late or early
> birds??? Mid-June shorebirds can be difficult to call early or late
> sometimes and could even be birds that never make it to the breeding
> grounds versus birds already headed south from the breeding grounds.
>
> Today saw five Whimbrel at Pony Slough in North Bend.
>
> Listening for unfamiliar songs with my windows down as I drive around
> town- the first two weeks of June the best time for vagrants on the coast-
> since there is so much habitat they can show up just about anywhere...
>
> Merry late migration!
> Tim R
> Coos Bay
>

 
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