Perhaps paramount in importance when it comes to studies of migratory birds has been the development of ever-smaller pieces of hardware that allow us to attach equipment to birds in a way that doesn't impede their everyday lives. While we know a lot about where migratory shorebirds breed and where they spend the winter, we still need to know more about their migration routes and the timings of their migrations. This information can be gained by attaching geolocators (small data logging units) to birds and here, NJA's vice-president for research, David Mizrahi offers us the latest insight from this technology:
FIRST EVER GEOLOCATOR RESULTS FOR A SEMIPALMATED SANDPIPER SHOW REMARKABLE YEAR-LONG ODYSSEY
Biologists from Manomet Center for Conservation Science, New Jersey Audubon, U.S. Fish and Wildlife Service, Kansas State University, the Wildlife Conservation Society, the Canadian Wildlife Service, Simon Fraser University, the Government of Nunavut, and Université de Moncton have coordinated the first effort to use geolocators to understand the migratory pathways of this species.
Geolocators record changes in ambient light levels, especially the rapid changes apparent at sunrise and sunset. Typically, daylight length is used to determine latitude, while the midpoint between sunrise and sunset is used to determine longitude. Recording light levels over time produces data that can be used to estimate locations of a bird throughout the year. To retrieve data from a geolocator, the bird must be recaptured.
Analysis of the data from the geolocators is key to understanding what the tiny units have recorded during the past year. The map [below] shows the first ever track of an entire year in the life of a Semipalmated Sandpiper from the eastern Arctic, the population which appears to have decline significantly over the last 30 years. This particular bird, a male, flew a total distance of ~16,500 kilometers, (~10,300 miles) in the past year. He also made a remarkable six day, 5,250 kilometer (nearly 3,300 miles) nonstop flight across the Atlantic Ocean from James Bay to South America, before moving on to his wintering area in Brazil.
Semipalmated Sandpiper with geolocator fitted to its leg [photo DavidMizrahi/NJA]
Data mapped from a recovered geolocator, fitted to a male Semipalmated Sandpiper (click on picture for a larger version) [photo David Mizrahi/NJA]
You can help!! Adult Semipalmated Sandpipers will be returning through our area in the coming weeks, with juveniles appearing through September and October. Keep a close eye on birds and report any that you find wearing colored leg flags, taking care to record the alphanumeric symbols as accurately as possible. Sightings can be reported via the bird banding website and your reports will go toward providing researchers with valuable data on these birds [photo by Mike Crewe].