Subject: [Tweeters] Finches Eating from Road Surfaces
Date: Jul 21 14:38:23 2010
From: Scott Carpenter - slcarpenter at gmail.com


Although not in Washington, I recently came across a mixed flock of Pine
Grosbeaks, Pine Siskins, and Cassin's Finches eating something from the
surface of a dirt/gravel road in a national forest. The location was in
Routt County, Colorado, along CR 38 between the town of Steamboat Springs
and Buffalo Pass in the Zirkel Wilderness. The location was much closer to
Buffalo Pass than Steamboat Springs.

My guess, though I don't know for sure, is that this road is not salted
during winter, leading me to believe these birds were eating either dirt or
rocks. They were definitely ingesting dirt and rocks, though perhaps their
goal was to ingest something attached to the dirt and rocks. My guess that
the road is not salted is based on the fact that the road is in a national
forest, it has gates (and signs) for closing it during the winter, it is in
a high elevation area that receives a large amount of snowfall, and the
generally poor condition of the road (one of the worst I've been on, with
big rocks, craters, etc.). Of course, I could be wrong. Along the lines of
salt consumption, perhaps the birds are after minerals delivered by the snow
melt? Or perhaps they are simply after grit to aid in digestion of seeds?

Photos of this, including the road surface, can be seen at:
http://www.westerngrebe.com/PineGrosbeak/

Scott Carpenter
Portland, Oregon

On Mon, Jul 19, 2010 at 9:39 AM, Kelly McAllister
<mcallisters4 at comcast.net>wrote:

> I've seen flocks of Pine Siskins and Red Crossbills on US 2 near Steven's
> Pass, during winter. I've also seen what I thought was unusual bevavior of
> "winter finches" under bridges. A pair of Evening Grosbeaks were totally
> absorbed in eating the dirt under the Indian Creek bridge, US 12, near
> Rimrock, a couple of summers ago. I approached very close and they paid no
> mind to me at all. Also on US 12, this past spring, a flock of Red
> Crossbills gathered under the Cora bridge on the Cowlitz River and pecked
> around among the rocks under the bridge. I think that Richard Carlson is
> probably correct that these attractions to particular patches of what
> appears to be gravel or bare dirt is salt-seeking behavior. I wonder if the
> roadside patches that Christy saw the birds frequenting might have been some
> kind of stockpile locations for gravel mixed with salt or maybe they were
> places where run-off water, laden with salt, pooled up and evaporated. There
> are some interesting dynamics here that I'd like to better understand.
>
>
>
> Kelly McAllister
>
> Olympia, Washington
>
>
> ------------------------------
>
>
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