Closely related bird species occurring in different continents are always a special challenge for keen birders. It is not too long ago, that ornithologists found out, that a Least Tern (Sterna antillarum) was found in East Sussex. This was new to Britain and the Western Palearctic. Also on other sites along the western coast of Europe and Great Britain, you might have chances to see (and compare) 2 small terns of the genus Sternula. Sternula is a genus of small white terns, which is often subsumed into the larger genus Sterna. Least Tern was formerly considered to be subspecies of Little Tern but is now regarded a valid species besides the Little Tern, Sternula or Sterna albifrons.
In the case of a small Tern in East Sussex, a Little Tern, Sternula albifrons, with a distinctive ‘squeaky’ voice was discovered in a tern colony at Rye Harbour, East Sussex, in June 1983. The bird returned annually until 1992. Although it was dismissed initially as an odd Little Tern, comparison of sound recordings of the call with those of the North American form Sterna antillarum, together with the noticeably greyer rump and central tail feathers, led to the eventual realization that it was a different species (or at that time one of the New World races of Little Tern), known as ‘Least Tern’. Research into the calls of all races of Little Tern eliminated other possibilities and it was eventually accepted as an individual of the North American antillarum/athalassos/browni group. Although its distinctive advertising call drew attention to the bird in flight, when silent it was not separable from the many Little Terns present. It was seen to display and present fish to Little Terns, suggesting that it was a male, but there is no evidence that breeding took place.
Both species are never easy to separate in identification. Thus the images in the gallery of Least Tern (Sterna antillarum) shot at Pea Island NWR/ North Carolina/ USA might help to identify. More of the identification of Sternula Terns in Asia/Africa you find in that blog concerning Saunder’s Tern, Sternula saundersi, and Little Tern.
In order to meet the growing demand for top images of the rarer species of Palearctic Bird-lens.com has specifically made trips to remote places in Europe but also to other parts of the world. This to do everything to ensure excellent photos of the Birds of the Western Palearctic. The yield of pictures also of rare Western Palearctic birds is very good. The beautiful pictures that you see in the gallery are just first impressions of what you will find behind the tab “Picture- Store” very soon are. Just give a notice if you need a picture of a bird before the new images are online.