A high-tech satellite tag on the bird, first fitted in Dublin Bay in the Republic of Ireland, tracked it as it headed north to feed on the shores of Sanday in Orkney.
The GPS device, powered by a tiny solar panel, recorded the bird’s migration before it crashed on Sanday Island.
But it continued to signal and began traveling again, pinging its locations as a campsite, a pizza restaurant and then a residential street in Ealing West London.
Researchers are offering a £100 reward for returning the device, which is worth around £1,000.
They believe it was found off the Sanday coast and picked up by a holidaymaker who then flew back south to the UK capital.
Professor Stu Bearhop, from the College of Life and Environment at the University of Exeter, said the trackers are like tiny plastic building blocks powered by a tiny solar panel.
They are being stuck onto the large and distinctive black and white waders as part of a program with Dublin Bay Biosphere and are expected to fall off in spring.
Prof Bearhop said: “They are really interested in how best to conserve these birds and which habitats they need to make the most effort to conserve.
“So it’s really focused on what’s happening in Dublin, but we end up with birds in Iceland, the Faroe Islands, Shetland, Skye and some other places.”
The research is being conducted by graduate student Steph Trapp, who says the marker fell from the bird on April 7th.
It lay on a beach in Sanday until the end of May when it started moving again and eventually landed in London.
“Obviously the bird isn’t quite down there yet,” she said, “so we think someone must have found the tag while on vacation in Sanday and picked it up.”
“It feels a bit odd to be able to track their entire vacation, but the tags are programmed to record a fairly accurate GPS location every few hours.”
She added, “If we get it back, we can put it back into another bird in the winter of next season and get a larger sample size.”
Meanwhile, conservationists are investigating the discovery of a dead hedgehog on Barra that could threaten the island’s ground-nesting bird population.
It cost millions of pounds to remove hedgehogs from the Uists after a number were released in a garden to control snails in 1974.
A spokesman for NatureScot said: “We have received a report of a hedgehog being killed on the road in Barra on June 9th. It is the first evidence on the island. Trappers employed by NatureScot are currently on Barra setting up a network of live traps and camera traps to see if there are any other hedgehogs present. Two trappers’ tracking dogs are used to track down hedgehogs. All captured hedgehogs will be relocated and released in a safe place. Abandoning mammals on islands can cause great harm to native wildlife and is treated as a serious wildlife crime.”