Use of External GSM-based Transmitters for Seabirds: Preliminary Results and Recommendations for Future Wind-power Studies

Researchers have tracked raptors and other bird taxa using GPS-based transmitters with success using tags attached by Teflon-coated ribbon harnesses. Unfortunately deployment of similarly styled harnesses on seabirds has been... [ view full abstract ]

Researchers have tracked raptors and other bird taxa using GPS-based transmitters with success using tags attached by Teflon-coated ribbon harnesses. Unfortunately deployment of similarly styled harnesses on seabirds has been unsuccessful with the possible exception of some land-based gulls. Presumably this is due to harness and transmitter interference with foraging behavior (i.e. pursuit- and plunge-diving) via hydro- and aero-dynamic influences, plumage integrity (loss of waterproofing), and poor harness fit during migration when birds experience rapid changes in body mass. Consequently, researchers have had to deploy surgically implanted platform terminal transmitters (PTTs), which have lower precision and higher power requirements compared to solar-powered GPS transmitters and may contribute to mortality in some species. Although data from PTT transmitters can inform about broad-scale migration patterns, GPS-derived data have the necessary precision to capture fine-scale movement patterns, allowing researchers to better relate the influence of weather, resource availability, and hazardous conditions (e.g. structures, pollutants, etc.) which may predict conflict with offshore wind installations. To assess this level of data resolution with free-ranging marine birds we used a newly developed 32g solar-powered transmitter which logs hourly GPS locations (accurate to 3m) and transmits them to cellular towers. We tested new attachment techniques using custom-molded silicone harnesses and 3D printed transmitter adapters with the goal of eliminating the need for implanted transmitters. In April 2016, we deployed 10 of these devices on Northern Gannets (Morus bassanus) and 3 on Surf Scoters (Melanitta perspicillata) along the mid-Atlantic US coast to test the technology. Attachments and data captures were successful to date with high overall retention rates in both species. Long-term success is currently being assessed. Preliminary data have corroborated previous PTT tracking data from these species. Gannets spent 36% of their time offshore (>5.5km) flying at an average 13.3m (±18m) altitude. Four individuals traveled directly through Wind Energy Areas (WEAs) over the course of their migration north and one remained for several days within 3.7km of the WEA. Surf Scoters appeared largely restricted to areas close to shore, corroborating long-term PTT tracking data, with the exception of two individuals that traveled offshore between Cape Cod, MA and Bay of Fundy. This trip was completed within 6 hours and birds achieved a maximum estimated altitude of 330m. While this pilot work has shown promising results, improvements on transmitter design are needed to i) reduce aero- and hydro-dynamic influences, ii) improve attachment longevity, and iii) enhance altitudinal data accuracy with accelerometer sensors. These data will be instrumental in modeling habitat use, mortality risk, and the impact of weather on flight behavior for these species in the face of multiple proposed offshore wind-power facilities along the US Atlantic coast.