An amateur photographer has set the bird-watching world a-twitter after he accidentally took what appears to be the first photograph of a rare blue rock thrush in the United States.

Michael Sanchez, from Vancouver, Washington state, set up his camera at Hug Point in Oregon at dawn on April 21 hoping to capture photographs of a waterfall on the Pacific Northwest coastline.

As he waited for the sun to rise over nearby cliffs, Sanchez spotted what appeared to be a blackbird hopping in the foreground. Sensing the light was good, he took a few shots.

When he checked his camera later, he noticed the bird was not black but had mysterious blue and chestnut-coloured plumage. The next day he posted the photograph to his Facebook