Tracking the flyways of Openbills using satellite telemetry

Asian Openbills were trapped from their nests by hand net during the night. Being colonial breeders, the birds built several nests in the same tree (Fig. 7a). The birds were given physical examinations for health status. Oropharyngeal and cloacal swabs were collected and kept in separate tubes of viral transport media, and 1–2 ml of blood was collected from the wing vein or jugular vein. All birds were screened at the study sites for influenza viral infection by detection of the influenza viral antigen in swab samples using immunochromatography (BioChek, London, UK). Other aliquots of swab samples and blood specimens were sent for further complete investigation of H5N1 HPAI infection at the Virology Laboratory, Faculty of Veterinary Science, Mahidol University. None of the Openbills screened was infected with the H5N1 virus.

Tagging of the Asian Openbills: (a) An overcrowded colony of Openbills with several nests on each tree; (b) Tagging an Openbill with a satellite transmitter and a ring band

Five healthy adult Openbills negative for influenza viral antigen were selected from colonies in the three study sites for flyway monitoring by satellite telemetry. Each of these Openbills was tagged with a ring band and fitted with a 35-g-solar power PTT-100 or a 40-g solar Argos/GPS PTT-100 satellite transmitter (Microwave Telemetry Inc., Columbia, MD) on its back with a Teflon harness (Bally Ribbon Mills, Bally, PA) (Fig. ​(Fig.7b).7b). The solar PTT-100 transmitters operated at a frequency of 401.650 MHz with a standard duty cycle of 10 h on and 24 h off for recharging the batteries. The solar-powered Argos/GPS PTT-100 satellite transmitter was attached to a tiny GPS receiver for locations with higher accuracy [29]. This transmitter package weighed about 0.06% of the birds’ body weights. The birds were freed at the capture sites within 1 h after tagging. The activated satellite transmitters attached to the Openbills emitted ultra-high frequency signals that could be detected by special ARGOS receivers on a polar-orbit weather satellite. The data on locations of the tagged birds were retrieved from the emitted signals, recorded and relayed to a ground station in the United States every two days, and subsequently to the server of Argos CLS Company (Toulouse, France). The data on bird movements at location classes 1, 2 or 3 according to Argos was analyzed in our data manipulation laboratory, and further mapped with Google Earth Program version 7.1.5 (Google, Mountain View, CA, USA) to obtain the real-time location of birds with a precision of less than 1500-m error. If the emitted signals lost for longer than one month, it implied that the transmitter-tagged bird was sick or dead, then the flyway monitoring was terminated.