Many birds migrate at night to and from their wintering & breeding grounds, and during these nocturnal flights many utter short vocalizations to keep in touch (audio example below). This project involves a transect of listening stations across the Lower Rio Grande Valley of South Texas (LRGV) that monitors the night sky for such migratory bird calls. Seven stations are currently operating from Port Isabel to Roma, TX. Most are located at schools and offer options for student participation. Automatic call detectors are being evaluated for their accuracy in detecting and identifying nocturnal flight calls. And nightly automatic detections of several species are posted each morning by 9am EDT to an archive. Call detection summaries provide a unique insight into the migration timing of some of the species being acoustically monitored across south Texas. This project welcomes participation from additional schools, businesses & institutions in the LRGV.

The audio link above plays a 26-minute segment of avian night flight calls during a dense migration over Harlingen High School South. The audio was recorded just before midnight on 28 April 2023 and includes hundreds of the Dickcissel's low "brrrt" flight calls, constant whistle notes from Swainson's Thrush, and calls of many other night migrating birds. Throughout the recording one can hear the low tremolo of a Lesser Nighthawk that is nesting on the roof.