Thursday, February 24, 2011

Barely Spotted Towhees Get Super Spotted Visitors

Spotted TowheeMale Spotted Towhee, Beaverton, Oregon, 19 February 2011 by Greg Gillson.

 

The Spotted Towhee above is typical of the "Oregon Towhee" (Pipilo maculatus oregonus), the subspecies of Spotted Towhee found west of the Cascades in Oregon, Washington, and coastal SW British Columbia. It is the least spotted of all Spotted Towhee populations with reduced white on the wings, scapulars, and tail. Compared to all other races it truly is barely spotted.

 

Spotted TowheeFemale Spotted Towhee, Beaverton, Oregon, 18 February 2011 by Greg Gillson.

 

Above is the grayish-brown female Oregon form of Spotted Towhee. She is even less spotted than the male. Both sexes of the Oregon Towhee have deeper brown (less orange) sides than other forms of Spotted Towhees.

Because the winters are mild where this form breeds, these towhees don't undergo a north-south migration, and most birds are thought to be residents, but there are some seasonal movements in and out of some locations.

These aren't the most artistic photos I have of Spotted Towhees--you can see a piece of the base of the bird feeder in two shots, and I'm looking down on the birds rather than the preferred level photo angle. But there they are, right outside my window. So, I can sit here and type a few lines and stand up, turn around, and snap another photo.... Oops, there, I did it again! I can't get any work done here--I love it!

But I wanted to show you the above birds first, so that I can show you the next photos. The birds below are apparently the "Nevada Towhee" (Pipilo maculatus curtatus), the form of Spotted Towhee found east of the Cascade crest from interior southern British Columbia and Idaho, south to northeast California and central Nevada.

The Nevada Towhee may winter sparsely in their breeding territories, but most seem to migrate to Arizona and southern California, and Sonora, Mexico.

I can find no documented occurences of Nevada Towhees in western Oregon. Thus I present the following photos.

 

Spotted TowheeSpotted Towhee, Beaverton, Oregon, 18 February 2011 by Greg Gillson.

 

The photo above is an apparent male Nevada Towhee, perhaps the first documented occurence in western Oregon. However, there are two of them. The following bird is even more spotted, super-spotted, if you will.

 

Spotted Towhee
Spotted Towhee, Beaverton, Oregon, 18 February 2011 by Greg Gillson.


 

Notice that these birds have more spots on the wing and scapulars. The outer tail feathers are edged in white and the tail spots are very large. The orange sides are a bit paler than the Oregon form.

You may notice that the primary wing feathers of all these birds are more brownish and worn than other blackish feathers of the wing, back, and tail. These molt limits indicate these are all one-year-old birds. Next fall they will molt their wing feathers and enter full adult plumage, never again to be aged by plumage.

On the female Oregon Towhee and the lower Nevada Towhee, you can see some white pin-feathers in feather sheaths on the face near the eyes, indicating active body molt.

At least for the Oregon Towhee, adults probably remain on their home territory year round. Young of the year venture out and establish their own territories. Thus, it is possible that come spring, these young birds will move on to better breeding territory than my backyard. Since there are no adults here now at all, maybe the habitat is not good enough for breeding. We'll have to wait and see.

The two Nevada Towhees above will no doubt migrate back over to the proper side of the Cascades here in a few weeks.

We have discussed Spotted Towhees before.

Addendum:

This female, and slightly aberrant (see rusty crown patch) Nevada Towhee put in a one-day appearance on 23 February 2011.

 

Spotted TowheeSpotted Towhee, Beaverton, Oregon, 23 February 2011 by Greg Gillson.

 

5 comments:

  1. Greg, you might check your Pyle about SPTO page 537. Interior group.

    ReplyDelete
  2. This post generated much discussion on the Oregon Birders OnLine (OBOL) email group, specifically in my identification of these highly-spotted birds as _curtatus_.

    There are several subspecies that fit this general appearance, including _montanus_ and _arcticus_.

    There are two points of view, equally valid.

    One: In over 150 years of collecting and banding, these other forms have never been documented in Oregon (and only once in SE Washington to 1953). And _curtatus_ is the common form east of the Cascades.

    Two: Other birders seem to notice highly spotted towhees in winter at their feeders, too. Since NO FORM of highly spotted towhee are documented in western Oregon, there is no telling what form these may actually be.

    The Oregon Towhee has dark outer webs on the tail feathers and a "thumbmark" of white on the tail corners. The highly spotted towhees I photographed could match a number of interior forms of towhees, including the only other one known from Oregon, the Nevada Towhee, with white web on outer tail feather and terminal spot equal to half the length of the exposed tail feather, beyond the tail coverts. Unquestionably, there are two forms in my photos.

    Why have these highly spotted towhees never been documented before in western Oregon if they are apparently so common now? Could it be that the wintering range of some of the eastern/northern forms have changed? Or were they here and just missed all this time?

    And why should subspecies even matter to amateur bird watchers anyway? That sounds like a good discussion for a future post!

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  3. Hey Greg, I am having the same experience and offer a possible explanation (guess):

    http://wildfidalgo.blogspot.com/2011/03/spot-check.html

    We sit at the northern reach of Puget Sound just inside Deception Pass. I agree we should not get too caught-up in subspecies and just enjoy the experiences. I have added you to my blog roll if that's OK. Thanks.

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  4. Greg, thank you very much for the additional info posted on my blog. I was going to update the post, then decided there was enough to justify a new post:

    http://wildfidalgo.blogspot.com/2011/03/hitting-spot.html

    Thanks again,
    Dave

    ReplyDelete
  5. The spotted towhee in our yard appears to have lost it's tail. Have you ever seen this and any idea what may have happened?

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