There are areas in western Washington where iron oxide is particularly
concentrated in surface and near-surface waters. Whatcom County is rather
notorious among public works folk who try to find new domestic water
supplies without pesky iron. The next time you drive around the area north
of Lynden, notice some of the roadside ditches; they are loaded with iron
oxide. And I'm sure there are areas with iron concentrations in Skagit
County where most of the birds winter, as well.

Thus, it's not too surprising that many of the birds become stained. What
is very puzzling to me, however, is why only the heads and necks become
stained. Their bellies must be regularly exposed to the same staining, as
they waddle about the fields and mud flats and swim in iron rich backwaters,
but the bellies seem to remain nice and white.

Are we sure that this ferrous coloration is indeed staining rather than
pigmentation? And are we sure that it is resulting from iron and not from
organic color?

Dave Nunnallee
dnun461 at ecy.wa.gov
Bellevue, WA