I look at a lot of birds every year, and I don’t see many
that are as cool as this one, a leucistic Black Turnstone (Arenaria melanocephala). This striking bird is wintering at the end
of Sandy Point, north of Bellingham, Washington, in a flock of its relatives,
and I finally got around to checking it out in February. I found the flock
feeding on rocks at the mouth of the marina there.
What a bird! From a distance it looked entirely white, but
at close range elements of the pattern became visible, most of them very
subdued. The more or less straight line across the breast identified it as a
Black rather than a Ruddy Turnstone (Arenaria
interpres), which has a bilobed pattern of black there. There was also a
Ruddy with the flock.
By comparing the bird with a normal Black Turnstone, I could
see how much the melanin pigment was reduced on this bird, yet it wasn’t
entirely absent. The darkest areas of normal pigment were on the rump and tail,
but tan areas all over the bird, most readily seen in flight, gave me a good
hint of typical Black Turnstone pattern.
The bird is definitely leucistic, not albinistic, because it
has normally pigmented eyes. Albinism is the complete absence of melanin pigment.
Because that pigment is what gives brown eyes their color, when it is lacking in
an albino, the blood vessels in the eyes give them a bright red color. Leucism
is a reduction of all pigments, but not necessarily their absence.
The bird presumably grew most of its feathers in July and
August, the time of fall molt in Black Turnstones, so they were about six
months old in February and showing their age. In comparison with nearby normal
birds, the primary feathers were distinctly more worn. The tertials, the long
feathers that overlie the primaries, were very worn, much more than on the
other birds.
The bright orange legs of this bird contrasted with those of
normal Black Turnstones, in which they are brown to dull orange. Presumably in
normal birds, melanin masks what would be bright orange otherwise. The legs of
Ruddy Turnstones are bright orange, and one wonders whether they would remain
exactly the same in a leucistic bird.
Its behavior appeared to be the same as that of the other
birds, and they must have accepted it as a flock member. However, when the
entire flock flew away, startled by a jogger coming down the beach, the white
bird flew in the opposite direction with two of the black ones rather than with
the flock.
Such birds are extremely rare, and I feel fortunate to have
seen this one. One thing special about it is that it could never be mistaken
for another turnstone, thus always recognizable. If we could recognize all
birds individually, we would know a lot more about them!
The white turnstone’s presence is being monitored closely,
so we may know when it has departed for the north, assuming some local falcon
doesn’t pick it out of the flock. It is well known that birds of prey will home
in on odd-looking birds, as they are easiest to follow in a twisting, turning
flock.
If it does persist into spring, local birders will be
watching closely for it late next summer, when Black Turnstones return here
from their breeding grounds in the Yukon/Kuskokwim River delta. Let’s hope it
makes it back.
Dennis Paulson
