Field-testing a new miniaturized GPS-Argos satellite transmitter (3.5 g) on migratory shorebirds

Smaller bird species, including many shorebirds, are difficult to track throughout the annual cycle because of technological limitations (tag weight and accuracy) and logistical constraints (the improbability of recapturing tagged individuals). Such limitations impede both conservation efforts and general ecological understanding for these species. To help advance tracking technology for birds <300 g, we tested for the first time a newly-developed technology, the smallest available (3.5 g) certified GPS-Argos satellite transmitter. We also tested a full-body harness attachment for the tags on long-distance migratory shorebirds that undergo substantial mass changes before and after migration. Of the 38 GPS-Argos tags that we deployed on three species, we received data from four tags. Although we had little success with the tags, two of the successful transmissions revealed potential breeding locations for the federally-threatened Red Knot Calidris canutus. Success of the full body harness was based on transmissions or observations of birds carrying them after completion of a migration. Although there may be risks for researchers who test cutting-edge technology and methods, feedback between researchers and manufacturers during field tests of new devices, and among researchers during tests of new attachment methods, are important steps in the advancement of tracking technology. Our testing and results directly contributed to engineering refinements of the PinPoint GPS-Argos satellite transmitter, the development of new generations of the tag, and subsequent successful deployments.