BirdOriTrack: a new video-tracking program for orientation research with migratory birds

Resumen

Experimental research on the orientation of migratory songbirds is traditionally conducted using orientation funnels or automatic registration cages that record the directional activity of individual birds on paper or a computer. Most traditionally used funnel and cage designs do not permit investigators to observe detailed behavior of the birds and, therefore, we have gained little insight into the actual behavior of birds while they are exhibiting migratory restlessness and making directional choices. Such behavior can only be studied by direct observation or by video filming. Here, we present BirdOriTrack, a video-tracking program for extracting time-resolved, positional data of birds (and potentially other animal species) to determine their orientation relative to the center of a circular cage/funnel. With relatively inexpensive cameras, recording equipment, and cages, orientation experiments can easily be conducted and analyzed using BirdOriTrack. The program is designed to be flexible, allowing analysis of orientation behavior of birds of any size in different cage designs and in both controlled laboratory settings and field-based studies. To demonstrate the program's utility, we show the results of preliminary field experiments on several species of migratory birds captured at a migration monitoring station. BirdOriTrack is freely available at http://canmove.lu.se/birdoritrack. BirdOriTrack: un nuevo programa de video seguimiento para el estudio de orientación en aves migratorias Tradicionalmente la investigación experimental sobre la orientación de aves migratorias se ha realizado usando embudos de orientación o cajas de registro automático, que graban la direccionalidad de la actividad individual de las aves en un papel o un computador. La mayoría de diseños tradicionales de embudos y cajas no permiten a los investigadores observar detalles del comportamiento del aves mientras éstas exhiben inquietud migratoria y toman decisiones direccionales. Éste comportamiento solo puede ser estudiado por observaciones directas o filmaciones. Aquí presentamos BirdOriTrack, un programa de video seguimiento para extraer datos temporales de posiciones de aves (y potencialmente otras especies de animales) para determinar su orientación relativa al centro de una caja o embudo circular. Con BirdOriTrack, experimentos de orientación pueden ser fácilmente realizados y analizados usando cámaras de costo relativamente bajo, equipo de grabación y cajas. El programa esta diseñado para ser flexible, permitiendo análisis del comportamiento de orientación de aves de cualquier tamaño en distintos diseños de cajas y tanto en ambientes controlados de laboratorio, como en estudios de campo. Para demostrar la utilidad del programa, mostramos los resultados de un experimento de campo preliminar en varias especies migratorias de aves capturadas en una estación de monitoreo de migración. BirdOriTrack está disponible de manera gratuita en http://canmove.lu.se/birdoritrack. Disclaimer: Supplementary materials have been peer-reviewed but not copyedited. Fig. S1. The Graphical User Interface (GUI) of BirdOriTrack. Fig. S2. Setup at Falsterbo Bird Observatory, Sweden. Fig. S3. Outdoor setup at Braddock Bay Bird Observatory, NY, USA. Fig. S4. Indoor setup at Tovetorp Field Station, Sweden. Fig. S5. Demo movie of the orientation of four Blackcaps, each recorded by a separate camera for 6 min at 5 frames/s (2000 frames) and saved as a quad-view movie (click to view either an AVI version or a WMV version). Fig. S6. Demo movie of the orientation of three White-throated Sparrows recorded with one camera for 11 min at 3 frames/s (2000 frames) (click to view either an AVI version or a WMV version). Fig. S7. Demo movie of the orientation of four Lesser Whitethroats recorded with one camera for 6 min 40 s at 5 frames/s (2000 frames) (click to view either an AVI version or a WMV version). Fig. S8. Demonstration of how the positions of a bird are extracted using frame differentiation from video images recorded at 0.3-s intervals (3 frames/s). Fig. S9. Tracking results of the demo movie from Falsterbo Bird Observatory. Fig. S10. Tracking results of demo movie from Braddock Bay Bird Observatory. Fig. S11. Tracking results of demo movie from Tovetorp Field Station. Fig. S12. Compensation for camera distortion. Fig. S13. Activity measured with the relative radius r = 1 as unit. Fig. S14. Tracking results from bird 1 (upper left), bird 2 (upper right), bird 3 (lower left), and bird 4 (lower right) from the demo video from Falsterbo Bird Observatory. Fig. S15. Tracking results from bird 1 (upper left), bird 2 (upper right), and bird 3 (lower left) from the demo video from Braddock Bay Bird Observatory. Fig. S16. Tracking results from bird 1 (upper left), bird 2 (upper right), bird 3 (lower left) and bird 4 (lower right) from the demo video from Tovetorp Field Station. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.