A once in a lifetime opportunity has literally dropped out of the sky in Massachusetts, where bird watchers have spotted an incredibly rare Steller’s sea eagle along the banks of the Taunton River. Native to the Kamchatka Peninsula in the far east of Russia, these colossal raptors have never previously been seen on any Atlantic coastline.

Easily recognizable thanks to their striking orange beaks and snow-white tails, Steller’s sea eagles have a wingspan that can reach 2.5 meters (eight feet) and are among the largest birds on the planet. Numbering just a few thousand, these amazing creatures breed along the coastlines and islands of the Sea of Okhotsk and the Bering Sea, sometimes migrating to Japan or Korea in winter.

However, writing on his blog The Birdist earlier this week, Nick Lund, who represents Maine Audubon, announced the appearance of this incredible flying behemoth on the east coast of the US. “The size stands out -- a pair of juvenile Bald Eagles perch just above it but are dwarfed by the Steller's,” he wrote.

The same bird originally appeared in Alaska back in August 2020, where local birders made note of a white spot on its left wing. Even more surprisingly, in the spring of this year, word got out that a Steller’s sea eagle had been spotted in Texas. It seems highly likely that this was the same individual, yet its distinctive wing pattern could not be confirmed because it was only seen perched rather than in flight.

In July, however, the same bird was reported in Quebec and New Brunswick, before going off the radar until last month, when it re-appeared in Nova Scotia. Speaking to the New York Times, Lund explained that the eagle’s tour of Canada was “like an elephant walking up out of Africa into Scandinavia [or] like getting a call that the Rolling Stones are playing in a field behind a warehouse in the next town over.”

By showing up in Massachusetts, however, the bird has now entered uncharted territory for its species and looks set to spend Christmas almost 8,000 kilometers (5,000 miles) from home.

As rare and unexpected as this sighting may be, it isn’t all that uncommon for birds to stray from their range and become vagrant. In most cases, vagrancy occurs when a bird becomes thrown off course or disoriented due to unusual weather, or because of some internal navigation error.

Speaking to NPR, Alex Lees, a lecturer of conservation biology at Manchester Metropolitan University, explained that this eagle probably ended up in Massachusetts due to "a failure to switch off the instinct to disperse or a failure of its navigatory apparatus."

According to Lees, the fact that the bird hasn’t returned home in well over a year means that it probably never will.