Common Tern

Sterna hirundo

Listening for this one

Not yet heard at the dock. We are listening.

Hear the call

Reference recording · 42 sec

Aviceda via Wikimedia Commons, CC BY-SA 3.0

What we're listening for

We have not picked up the Common 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 common tern is a seabird in the family Laridae. This bird has a circumpolar distribution, its four subspecies breeding in temperate and subarctic regions of Europe, Asia and North America. It is strongly migratory, wintering in coastal tropical and subtropical regions.

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