Myrtle Warblers Take 6,800-Mile Detour to Gulf Coast as Tiny Tags Sharpen Migration Maps
Updated
Updated · The Conversation · Sep 6
Myrtle Warblers Take 6,800-Mile Detour to Gulf Coast as Tiny Tags Sharpen Migration Maps
2 articles · Updated · The Conversation · Sep 6
Summary
Dozens of multisensor geolocator backpacks showed Anchorage-breeding myrtle warblers flew east across Canada and then south to the Gulf Coast, overturning expectations that they wintered mainly along the Pacific Coast.
The 6,800-mile round trip was reconstructed after researchers recaptured tagged birds a year later and downloaded pressure, light and wind data from Tic Tac-size devices.
Barometric geolocation improves on older light-level tags by using air-pressure changes and weather matching to pinpoint stopovers and flight timing more precisely, especially around equinoxes when light-based estimates weaken.
The circuitous route may reflect ancient post-glacial range expansion encoded in migration behavior, while future tagging of California-wintering birds could explain why some warblers appear to follow a different path.