Update: from May 05, 2011: an adult almost in full alternate plumage aspect:
Update: from May 05, 2011: a selection of birds of various ages and plumages/molt stages:
May 24, 2006: this photo is from August 2005; a very pale-headed (molting) adult:
This one from May 24, 2006 has somewhat reddish legs:
This juvenile Black Tern (Chlidonias
niger) was at Benbrook Lake, Tarrant County, Texas
on September 18, 2002. In flight it appeared to show a gray band
along the flanks from the darker shoulder patch to the rear of
the wing (contrasting with the white belly), as expected for the
Nearctic form surinamensis. However, the pattern of black
on the head appears virtually identical to the norm for nominate
niger. The head pattern for surinamensis is typically
less-full, with a shorter extension of black down the nape, and
with much more white in the crown - often looking white-streaked-black
rather than the opposite, and thus being much closer to the head
pattern of White-winged Tern (C. leucopterus). Compare
this bird to the two perched juvs in plates 185, 187 of TERNS
by Olsen and Larson.
While surinamensis has been documented in Western Europe,
niger has not yet been documented in the Americas (update: - there are two claims of niger
from Barbados) - surely it occurs here at least as often as C.
leucopterus? This individual demonstrates more variation in
surinamensis than previously described. In addition to
the different flank markings, there may be a difference in the
patagial coverts (leading lesser underwing coverts):- contrastingly
dark in surinamensis, but uniform with the other underwing
coverts in niger - as first pointed-out by Anthony McGeehan
in BIRDING WORLD:
Update: Sept 21, 2002: added to
bottom of page some comparative images of niger, surinamensis,
and Chlidonias leucopterus, thanks to Norman Van Swelm who kindly sent
me some interesting comparative images from the Netherlands:
a) juvenile C. n. niger, October:
b) juvenile C. n. niger, October:
c) Claimed juvenile C. n. surinamensis, November, in the
Netherlands. I have been informed that this sighting has not
been submitted or reviewed by the Dutch RBC - my apologies if
I created the impression it was a formally accepted record - but
it IS a good candidate:
d) adult and Juv. C. n. niger, October:
In this zoom (below left) of the rightmost niger above,
note the pale but visible patch of gray on the flanks immediately
to the right of the dark shoulder patch; note the different extent
and shape of this gray on the flank compared to the surinamensis
above, and this one from Texas in Aug(below right, by Martin Reid):
e) juvenile C. n. niger from England in September (by Martin
Reid) - it too has a small amount of light gray on the flanks
behind the shoulder patch:
Finally here is a juvenile White-winged Tern (C. leucopterus)
from England in August (by Martin Reid):
