Benton County Swainson's Thrush

[Karan Fairchild]

Hi All-

This morning I heard a SWAINSON'S THRUSH calling several times, in the shrubbery near our house, in the eastern foothills of the Coast Range. Seems a bit on the late side for us, maybe others are still having them?

Karan Fairchild

6mi SW of Philomath

[Don Boucher]

Hi karan,

I heard Swainson's Thrush calls in the sky last night. In previous years, I've heard and seen reports of their nocturnal calls into the third week of October, but these reports are very few.

-Don Boucher

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[Mary Garrard]

A couple of nights ago I heard some Swainson’s calls in the early morning in the trees behind my house. Nice to hear them for probably the last time until spring!

Mary

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[howard bruner]

Hi Karan

I too am hearing unexpected numbers of SWTH - both on the night wing and in a variety of local places in the morning in and around Corvallis. 

H 

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From: mid-vall...@googlegroups.com <mid-vall...@googlegroups.com> on behalf of Karan Fairchild <alde...@peak.org>
Sent: Sunday, October 5, 2025 7:09 AM
To: Oregon Birds Online <ob...@freelists.org>; Mid-Valley Nature <mid-vall...@googlegroups.com>
Subject: [MidValleyNature:7915] Benton County Swainson's Thrush

 

[Karan Fairchild]

Thank you all for the comments about Swainson's Thrushes- it's been very interesting. It's nice to know they're still around in many places, and may be for some time!

Karan

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From: "Karan Fairchild" <alde...@peak.org>
To: "Oregon Birds Online" <ob...@freelists.org>, "Mid-Valley Nature" <mid-vall...@googlegroups.com>
Sent: Sunday, October 5, 2025 7:09:01 AM
Subject: Benton County Swainson's Thrush

[Joel Geier]

Others have commented on the phenology for Swainson's Thrushes.

I just want to add a bit on "detection probabilities."

From 10+ years of intensively monitoring Oregon Vesper Sparrows on nesting sites around Corvallis, Bob Altman, Lisa Millbank and I have learned that these birds are around for at least a week or more, on either end outside of what birders have generally regarded as the season for finding these birds.

The bar charts on eBird indicate that Vesper Sparrows are "rare" after the 3rd week of September. But if you know where to look (and have access, which is kind of key for this species), they can be found reliably in numbers, right up to the last few days of the month. On September 29th I found three Vesper Sparrows in southern Polk County, near Airlie. Two of them were color-banded birds that have been in the same area for several weeks. The other one was unbanded, but likely part of the same group that we've been seeing.

We occasionally have resights of banded birds into early October (I think October 2nd is our record late date). But get this: When we put GPS tags on some birds a few years ago, and managed to recapture two of them the next spring, it turned out that both of them stayed on their expected sites even farther into October.

I seem to recall October 6th as the actual night of departure -- close to a full week after we usually even bother looking for lingering birds. That's at least two weeks after what might count as a "common wisdom" departure date for birders.

It's not like two GPS-tagged birds is a big sample, where you might expect to get "extreme values." This might well be ordinary. The birds might well still be around, but hard to detect, even in focused searches by people who know their favorite spots.

Adding to this, as recently as September 21st, we banded an adult Vesper Sparrow that was still undergoing molt, in a big way. Physiologically, songbirds can't really migrate until they're past their molt. Or until they've built up fat reserves (which were scant at best, up until around the last week of September).

All of this is just to suggest, the windows on migration might be somewhat wider than we realize.

Happy fall migration,

Joel

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Joel Geier

Tampico Ridge north of Corvallis