'Extremely rare' bird mysteriously migrates to Marin (Cal)

[intrepidity]

https://www.sfgate.com/news/article/rare-willow-warbler-bird-Marin-17542693.php

A small, 11-centimeter songbird has turned Marin County upside down.

The Eurasian bird — known as the willow warbler — was spotted at the Rodeo Lagoon in the Marin Headlands on Oct. 18 by William Legge of Mill Valley, the Marin Independent Journal reported. It’s thought to be the first-ever sighting on the North American mainland of the warbler, which has since brought excited members of the birdwatching community from across the United States to Northern California.

Willow warblers are delicate gray-green birds that typically breed in Europe and migrate to southern Africa for the wintertime, according to the Wildlife Trusts. They’re considered unusual for molting their feathers twice a year — but it’s even more unusual that one suddenly appeared in Northern California.

“For reasons that we're not quite sure yet, this one decided to fly west,” said Chris Overington, executive director of the San Francisco Bay Bird Observatory. “It's an extremely rare bird for the West Coast.”

Once word got out, the birdwatching community immediately took action. “Several hundred birders have continued some surveillance of this vagrant songbird since Tuesday,” the Golden Gate National Parks Conservancy website said Oct. 21.