Small flock of Caspian Terns (Hydroprogne caspia) and Elegant Terns (Thalasseus elegans) near Drakes Estero this morning (9 August 2025).
There are five Caspians on the left side and one in the far background. Note their larger size and more robust bills. Here's a close-up to compare the two species:
It's helpful to compare their bills -- the Caspian has a more robust, red bill, with a bit of black towards the tip of the bill. In contrast, the Elegant has a longer, thinner bill that's often more orange (or yellow) in color, rather than red. It can also look like it is curved downward because of the shape of the ridge of the upper bill.
The length and color of Elegant Tern bills vary quite a bit, so here's a close-up of Elegant Terns:
2 comments:
Am I to understand that the Caspian and Elegant terns are different genus?
Hi, Bill!
That's right, there are several genera of terns in Sonoma/Marin counties. It can be helpful to know that, as the different genera have different characteristics. As an example, in addition to Hydroprogne and Thalasseus, you can also find Sterna (e.g., Forster's Tern, Common Tern, Arctic Tern) and Sternula (Least Tern). (There are also others!)
:) Jackie
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