A tiny geolocator has uncovered a hitherto unsuspected extra-long migration by a Scottish Red-necked Phalarope.
An RSPB tracking device weighing less than a paperclip has helped scientists uncover one of the world’s great bird migrations. It revealed that one particular Scottish Red-necked Phalarope migrated thousands of miles west across the Atlantic to the Pacific Ocean, a longer journey than that recorded for any other European breeding bird.
In 2012, the RSPB, working in collaboration with the Swiss Ornithological Institute and Dave Okill of the Shetland Ringing Group, fitted individual geolocators to 10 Red-necked Phalaropes nesting on the island of Fetlar in Shetland, in the hope of learning where they spend the winter.
After successfully recapturing one of the tagged birds when it returned to Fetlar last spring, experts discovered that it had made an epic 16,000-mile round trip during its annual migration, flying from Shetland across the Atlantic, south down the eastern seaboard of the United States, across the Caribbean, and Mexico, ending up off the coast of Peru. After wintering in the Pacific, it returned to Fetlar, following a similar route.
Prior to this, many experts had assumed that Scottish breeding phalaropes joined the Scandinavian population at their wintering grounds, thought to be in the Arabian Sea, yet the destination of this bird turned out to be the Pacific Ocean.
Red-necked Phalarope is one of Britain’s rarest breeding birds, being found in only on Shetland and the Western Isles. Its numbers currently fluctuate between 15 and 50 nesting males. Scotland marks the southern limit of its breeding range, but the species is far more abundant further north where it occupies wetlands around the northern hemisphere.
In a reversal of traditional gender roles, in summer, the male birds can be found incubating eggs and raising young, while the female uses her brightly coloured plumage to attract new partners. In winter, phalaropes congregate in large flocks at sea in regions where currents create upwellings of cold, nutrient-rich water to support the blooms of plankton on which the birds feed.
By continuing the project and retrieving more tags from phalaropes after the next winter migration, ornithologists hope to learn the extent to which the Scottish population may be impacted by future changes at sea, how the species might respond to any change and whether any negative impacts in these wintering areas can be mitigated by conservation management here in Scotland.
The RSPB’s Malcie Smith said: “To think this bird, which is smaller than a Starling, can undertake such an arduous journey and return safely to Shetland is truly extraordinary. This tiny tracker has provided a valuable piece of the puzzle in building a picture of where the phalaropes go when they leave our shores. We hadn’t realised that some Scottish birds were travelling thousands of miles to join other wintering populations in the Pacific Ocean. Intriguingly, if the usual wintering area of Scottish Red-necked Phalaropes is indeed in the eastern Pacific, then this Scottish breeding bird may be directly affected by periodic ‘El Nino’ events when these Pacific waters become warmer and the supply of plankton is greatly reduced. With that in mind, the project – which we will continue – will be vital when considering future conservation of this rare and special bird.”