Crested Terns (Thalasseus Bergii) are very common in Australia and are likely to be seen around the entire coast of Mainland
Australia and Tasmania.
Lesser Crested Terns (Thalasseus bengalensis), on the other hand, are far less widespread in Australia and normally only occur along
the coastlines of Queensland, Northern Territory and the northern half of Western Australia. This, in my opinion, means that many
Australian birdwatchers are not likely to be very familiar with Lesser Crested Terns and will rely on their field guides or comments
from other birdwatchers for their identification process for that species. The two species are very similar in appearance and a
common method used by many birdwatchers to separate the species is to identify by bill colour. On the surface this seems easy and
reliable but I contend that this method requires some care when assessing breeding-plumaged birds of both species and can, in fact,
lead to incorrect identification.
I have created an on-line photo gallery which is intended to provide a graphic presentation of the differences and similarities of
the bill colours of Crested and Lesser Crested Terns. Some tips on other diagnostic features are given but the gallery concentrates
mainly on bill colours.
To see the photo gallery go to:
http://ptiloris.smugmug.com/
Then click on the "Identification Guides" icon;
Then click on the "Crested Tern v Lesser Crested Tern" gallery icon.
To see the largest size images click on each main image; to return to the thumbnail page click on the image or click on the "close"
button in the top right-hand corner.
People using dial-up connections or slow broadband may find the images a little slow to load, sorry, but I prefer to use high
quality images in my galleries.
There are 38 images each averaging around 200kb.
Cheers
Bob Inglis
Sandstone Point
Qld
Australia
http://users.tpg.com.au/inglisrc/
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