Our initial dataset of flight calls was collected through a series of nocturnal monitoring stations in Nova Scotia and identified by John Kearney of the Listening Together Project. (See Credits for more information.)

Identification was based on contextual information and experience, using the Old Bird guide as a foundation.

For more resources on nocturnal flight call identification, see this bibliography of NFC resources.


It is important to recognize that the calls on this site are presumed or putative calls. Some are likely misidentified.

Since nocturnal flight calls can be plastic and highly similar between species, they often defy 100% certain identification, especially during autonomous nocturnal monitoring. Because of this, identification of nocturnal flight calls is far from a solved problem: it is a work in progress. It has even evolved over the course of identifying the sounds contained in this guide.

This website is a "first crack" at making nocturnal flight call identification more accessible to the public. We hope to add more information and make corrections as time goes on.

Philosophy on uncertainty

The goal of this website is not only to provide information to the public, but also to encourage research into nocturnal flight call identification.

Toward this goal, we include putative identities for calls belonging to challenging bioacoustic complexes, such as the "Zeep" complex. This necessarily introduces errors in identification.

Instead of leaving uncertain calls unidentified, our philosophy is to account for the inevitable errors using appropriate scientific and statistical methodology. This approach enables scientists to make use of nocturnal flight call monitoring while simultaneously striving toward better identification.