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.

 

In summer 2024, seven bird call monitoring stations are operating 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 posted each morning by 9am EDT in a Vesper call archive.  See instructions for how to browse the archive. See 2024 Summer Data for data summaries.

 

In spring 2024, seven bird call monitoring stations operated from Port Isabel to Roma, TX (see map above), and two methods were tested for automatically detecting the distinctive low "brrrt" flight call of the Dickcissel (Spiza americana). In their spring migration, Dickcissels migrate from primary wintering grounds in Venezuela to breeding grounds across the heartland of North America. During the last week of April and first week of May, more than a million of these colorful sparrow-like birds may pass northbound over the Lower Rio Grande Valley of Texas. Nightly call totals from the monitoring transect were reported each morning at 2024 Spring Data.

 

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 minutes segment of this extraordinary audio recording that includes hundreds of the Dickcissel's low "brrrt" flight calls.

 

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