[Tweeters] Swainson's Thrush Arrival in Western Washington

Gary Bletsch garybletsch at yahoo.com
Thu Apr 12 07:28:55 PDT 2012


Dear Wayne and Tweeters,
 
Although I don't think I'd call it an "imitation" of Swainson's Thrush song by a Song Sparrow, I know exactly what Brad is talking about. Taken from the perspective of a human listening in on the birds, an imitation is what it amounts to.
 
Very often at the Game Range on Fir Island, and sometimes at a few other spots, I have heard Song Sparrows utter a single, whit-like note, always given as part of their song. In fact, I just heard it on Sunday on Cockreham Island.
 
Hearing the pseudo-SWTH for the first time this year, I was reminded of all the times I'd been with other birders who had called out "Swainson's Thrush," bringing about an all-out effort to find the bird. It always turned out that the "whit" they heard was given at the same time as a Song Sparrow's song. Eventually, everyone in the party would come to agree that they'd been hearing one note in the sparrow's song, a note that can sound uncannily like the "whit" of a Swainson's Thrush. I do think it's rather thoughtless of the sparrow to do this, right when we are trying to find our first SWTH of the year, but that's the sparrow's choice, I guess.
 
It would be interesting to find out whether this indeed constitutes mimicry, but I would defer to the scientists to figure out how on earth to ascertain such!
 
Yours truly,


Gary Bletsch
 
Near Lyman, Washington (Skagit County), USA
 
garybletsch at yahoo.com
 
"Nun," sagte ich, "wenn ich ein Taugenichts bin, so ist's gut, so will ich in die Welt gehen, und mein Glueck machen." Und eigentlich war mir das recht lieb, denn es war mir kurz vorher selber eingefallen, auf Reisen zu gehen, da ich die Goldammer, welche im Herbst und Winter immer betruebt an unserm Fenster sang: "Bauer, miet' mich, Bauer, miet' mich!" nun in der schoenen Fruehlingszeit wieder ganz stolz und lustig vom Baume rufen hoerte: "Bauer, behalt' deinen Dienst!"

--- On Thu, 4/12/12, Wayne Weber <contopus at telus.net> wrote:


From: Wayne Weber <contopus at telus.net>
Subject: RE: [Tweeters] Swainson's Thrush Arrival in Western Washington
To: "TWEETERS" <tweeters at u.washington.edu>, "BRAD WAGGONER" <wagtail at sounddsl.com>
Date: Thursday, April 12, 2012, 12:31 AM







Tweeters,
 
Brad Waggoner is bang-on in describing the pattern of Swainson’s Thrush arrival in western Washington.  I have kept track of spring arrival dates (and fall departure dates) of birds around Vancouver, BC since the late 1960s, and our arrival dates agree strongly with those in western Washington.
 
Every year, few if any Swainson’s Thrushes arrive before early May. However, there are enough records in mid- to late April to indicate that, some years, there are a few birds that arrive in advance of the main influx, perhaps as a “spring overshoot” during a period of warm temperatures and southerly winds.  Out of 32 years with arrival dates, 10 were in April, and 22 in May.
 
The mean arrival date for Swainson’s Thrushes at Vancouver is May 6; the earliest ever, April 16; and the latest ever, May 20.
 
Brad is also correct that Swainson’s Thrushes virtually NEVER sing when they first arrive. They are often on their territories for 2 weeks or more before they start to sing, and it is rare to hear one singing before mid-May. This habit of a delayed start to singing is also found in other “brown thrushes” such as Hermit Thrush and Veery, and is in contrast with most songbirds, which even sing on migration before they reach their breeding grounds. The brown “Catharus” thrushes don’t do that.
 
I will differ with Brad on one point; I’ve never heard a Song Sparrow make a call anything like the “whit” note of a Swainson’s Thrush. However, I will point out that most birders are not skilled at identifying birds by songs and calls (I don’t mean to include Brad!), and I have heard birders swear that they were hearing singing Swainson’s Thrushes, only to find on investigating that it was some other species. If you report a Swainson’s Thrush in April, it would be best if you saw the bird, and saw it well--  and even then, it’s easy to confuse a quickly-seen Hermit Thrush with a Swainson’s Thrush.  And if you do report a Swainson’s Thrush in April, expect to be questioned--  it’s unusual!
 
Wayne C. Weber
Delta, BC
contopus at telus.net
 
 
 


From: tweeters-bounces at mailman1.u.washington.edu [mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Brad Waggoner
Sent: April-11-12 7:47 PM
To: tweeters
Subject: [Tweeters] Swainson's Thrush Arrival in Western Washington
 
Hi All,

Just a word of note as far as to the arrival of Swainson's Thrushes here in Western Washington. As one that attempts to keep bird records here in the state of Washington, any Swainson's Thrush reported before the 3rd week in April would need to be fully documented for it to make a state record. I would personally probably make that even later in the month just based on my experience. They just do not arrive in our area really until the first of May.

What I have noticed is that Song Sparrows do an absolutely perfect Swainson's Thrush-like call note. Whether this is a note uttered prior to the start of a song or is just a one note call, I can't say for sure. I just know that I have been fooled many times by this imitation. 

Another thing I have noticed is that if I am lucky enough to detect or see a Swainson's Thrush in the early days of May, they have not been singing. Uttering their call notes, perhaps, but not singing. I normally don't hear them until mid May or after when they are establishing territories.

Just my two cents worth...............

Cheers and good birding,
Brad Waggoner
Bainbridge Island
mailto:wagtail at sounddsl.com


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