Preliminary Assessment of Thermal Imaging Equipped Aerial Drones for Secretive Marsh Bird Detection

Abstract

Rails are a highly secretive group of marshland obligate species that are difficult to consistently survey and detect. Current survey efforts utilize either call-playback or autonomous recording devices, but the low detection probabilities for rails create challenges for long-term systematic monitoring. Between 8 April and 16 May 2022, we flew a small aerial drone equipped with a thermal camera to survey for six species of rail (Back Rail [Laterallus jamaicensis]; Yellow Rail [Coturnicops noveboracensis]; Sora [Porzana carolina]; Virginia Rail [Rallus limicola]; Clapper Rail [R. crepitans]; King Rail [R. elegans]) along the Gulf Coast of Texas in order to assess the feasibility of long-term drone monitoring. We successfully conducted 34 flights and detected rails 55.5% of the time at known occupied points. We achieved 27 total rail detections, including 12 Black Rail/Yellow Rail detections. Of the birds detected, 81% exhibited no response to the drone’s first approach. We intend for this preliminary data to shape future survey protocol for secretive species occupying difficult to navigate terrain.