Hi, Jeff.

Finches seem to be among the few passerine birds, at least in this
region, that feed plant material to their young. Most seed-eaters
(sparrows, buntings, cardinals) feed insects to their young, so they
get a healthy dose of protein, including chitin, at least during the
breeding season. It may be that the finch diet of almost 100% seeds
needs to be augmented by minerals such as salt. They also eat a lot
of ash, and you can find crossbills and Evening Grosbeaks, at least,
feeding in fire pits in campgrounds at times. I should add that the
E. Grosbeaks I've seen doing this were also stuffing themselves with
spruce budworms at the time, so the ash wasn't a substitute for
animal matter in that case. Thus I may be completely wrong in this
speculation, but nevertheless the birds do eat minerals. Along with
this craving for salt is a craving for water - correlated or not -
that manifests itself in finches spending more time drinking than
other similar birds. That's just based on my own observations,
without any quantification.

Crossbills have been found drinking from mineral springs in
Washington and, apparently, poisoning themselves by doing so.

When the big invasion of finches was going on at Stevens Pass last
winter, there were great numbers of finches on the road, yet
seemingly very localized, as Rob observed. We saw large numbers of
Red Crossbills, Pine Siskins, and Evening Grosbeaks feeding at one
spot when we drove up in the morning, stopped the car next to them
and photographed them at pointblank range. They or others (surely
others) were at the same spot when we came back down about 4 hours
later. Several people wrote about the number of dead finches on the
road, and we saw the same.

Just this last weekend in Okanogan County we watched Red Crossbills
on a gravel road, and we could actually see them picking up little
pieces of gravel to swallow. Gravel is used by many seed-eating
birds, for example gallinaceous birds and pigeons, to grind up seeds,
but NOT usually used by the ones that crack the seeds and discard the
seed coat (sparrows, buntings, etc., as well as finches), so this
seems odd to me. Could they be eating the gravel to get minerals from
it?

Dennis

On Jun 20, 2008, at 12:00 PM, tweeters-
request at mailman1.u.washington.edu wrote:

> From: jeff gibson<mailto:gibsondesign at msn.com>
> To: Rob Sandelin<mailto:floriferous at msn.com>
> Sent: Thursday, June 19, 2008 12:53 PM
> Subject: Re: [Tweeters] Siskins and crossbills have a dispute
> over...gravel?
>
>
> Hi Rob.
>
> Crossbill's and Siskins both have a penchant for salt. I've read
> plenty about crossbills gathering road salt, and in 'big' crossbill
> years, I've seen them getting salt down at the tideline on the
> Olympic coast. I just looked up siskin's on the "Bent Life
> Histories' pages at Birdzilla.com ( an interesting source ) and it
> say's they have a 'salt habit' also, which I did'nt know.
>
> It's interesting that two finches that share wild population
> 'swings' would have a hankering for salt. My theory is that due to
> this genetic based addiction , that massive numbers of birds die
> from hypertension due to salt consumption, then the population
> rebounds. Hopefully an adult who know's what they're talking about
> will step in at this point.
>
>
> Jeff 'monkey brain' Gibson
>
> Everett Wa.

-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net



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