Hi all
I've just been looking at terns at Darwin sewage works. There are a
few White-winged Black Terns, and still lots of Whiskered, which
will leave us in the next couple of months.
At this time of year many Whiskered have only a narrow band of
black going around the back of the head. Through inexperience and
perhaps wishful thinking, this has caused claims of birds in this
plumage as Black-naped Tern, though clearly their presence in a
sewage works or at a swamp should discourage this to a great
extent, or at least set the alarm bells ringing.
The field guides probably add to the problem though, with none
seeming to show birds with a clear 'band' appearance around the
back of the head. Photos in "Terns of Europe & North America" (pl.
173 - and to some extent pl. 178) show quite well this effect, and I
have a couple of photos from the sewage works myself that clearly
show the 'naped' appearance.
Interesting that people tend only to think of confusing Whiskered
with White-winged Black without realizing that some can confuse
the Black-naped in there as well. It also shows the fallibility of
relying on single-feature identification.
Happy birding
Niven
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