Whilst working through the tern roost at the Krom River estuary in the Eastern Cape south of Port Elizabeth on Sunday, 13 March 2005, Jean-Marc Strydom came across a tern which worried him. It showed a full black cap and bright orange bill which all bode well for it being a Lesser Crested Tern Sterna bengalensis (this would have already meant a range extension of a few hundred kilometres as they do not normally occur much further south than just south of Durban), but the one thing that really worried him was the fact that it was showing a pink flush to the breast, a feature he was not aware of in this species.
The bird was also ringed (green over yellow on the left leg, white on the right) and on passing the ring combination on to Tony Tree, the bird was eventually tracked down to the Banc d'Arguin in Mauritania. It is apparently one of a study being made on a mixed pair of Sandwich Tern Sterna sandvicensis and Lesser Crested Tern Sterna bengalensis and their offspring over several years.
The hybrid tern photographed on the Krom River estuary.
It seems the information received on this bird was incorrect based on the following comments received:
From Laurent Raty of Belgium:
The parent bird on the pictures here:http://www.surfbirds.com/cgi-bin/gallery/display.cgi?gallery=gallery11&start=575
...is the same individual (green over yellow on the left tarsus, white on the right tarsus, metal on the right tibia).
It's not a bird from Banc d'Arguin in Mauritania (as the webpage indicates), but from Banc d'Arguin in France. Last time I heard, this bird
was unidentified and of unknown parentage - but it had been DNA-sampled, so things may have changed.
From Pierre-André Crochet of France:
As Laurent rightly pointed out, this bird is NOT the offspring of a mixed bengalensis X sandvicensis pair. It is a bird caught and ringed as an adult. It's identity is unknown: it is most similar to bengalensis, but with a white rump (pointing to elegans). It could conceivably be an atypical bengalensis (with a whitish rump), an atypical elegans (with a shorter and paler bill than usual, and a shorther crest; ok that's many atypical features...) or, perhaps more likely a hybrid, but not necessarily with sandvicensis.
I still have the DNA samples on my desk, and I'm waiting for samples of pure elegans and bengalensis to start the analyses.