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. This project involves a transect of listening stations across the Lower Rio Grande Valley of South Texas that automatically monitors the night sky for such migratory bird calls.

During 2024, seven stations monitored bird calls from Port Isabel to Roma, TX (see map above). Nighthawk 3.0 software and other detectors are being evaluated for their accuracy in automatically detecting nocturnal flight calls of Least Sandpiper, Black-and-white Warbler and Dickcissel. Nightly automatic detections of these species were automatically posted each morning by 9am EDT to an archive.  See instructions for how to browse the archive and see data for species detection summaries. In 2025, additional monitoring stations and species will be added.

The audio link below 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.