Many birds migrate to and from their wintering &  breeding grounds at night, 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 have been monitoring bird calls from Port Isabel to Roma, TX (see map above). Nighthawk 3.0 software is being evaluated for its accuracy in automatically detecting nocturnal flight calls of Least Sandpiper, Black-and-white Warbler and Dickcissel. Nightly automatic detections of these species, if there are any, are automatically posted each morning by 9am EDT to an archive.  See instructions for how to browse the archive. See Data for species detection summaries.

The picture below shows a time vs. audio frequency spectrogram of night flight calls during a dense migration over Harlingen High School South just before midnight on 28 April 2023. Clicking the spectrogram begins playing a 26-minute segment of this extraordinary audio recording that 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. Through the recording one can hear the low tremolo of a Lesser Nighthawk that is nesting on the roof.