Caspian Tern

Hydroprogne caspia

Listening for this one

Not yet heard at the dock. We are listening.

Hear the call

Reference recording · 6 sec

Joost van Bruggen via Wikimedia Commons, CC BY-SA 4.0

What we're listening for

We have not picked up the Caspian Tern at the dock yet. The microphones stay on day and night, so the first time one calls within earshot it will appear here.

How these counts work

5 microphones listen from the dock, day and night. They only count birds from a fixed regional list of 226 species, so a bird that cannot occur here is never added by mistake. Every species has its own confidence bar, and that bar rises when the wind picks up and the audio gets noisy. A bird is not counted until it turns up again across several short listening windows that together cover at least ten minutes. Because the bar sits that high, when this page calls a bird rare, it really is rare.

All of the microphones sit at one spot, our dock, so these counts describe what is audible from that shoreline, not the whole lake. A bird that stays quiet here, or sings out of earshot, can be nearby and still never reach the numbers.

These records are generated automatically from the audio, and no person reviews them one by one. The software is not perfect and sometimes tags the wrong bird, most often on a faint or distant call. Read each as a bird the microphones detected, not a sighting someone checked by hand.

About the bird

The Caspian tern is the world's largest species of tern, with a subcosmopolitan but scattered distribution. Despite its extensive range, it is monotypic of its genus, and has no accepted subspecies. The genus name is from Ancient Greek hudro-, "water-", and Latin progne, "swallow".

From Wikipedia, CC BY-SA 4.0 Read more on Wikipedia →