Unknown bird - description only

[Richard Larsen]

  I was hiking in Colorado around 12,800' on 8/19/20, 1000' above tree line, just tundra and rocks.  I almost stepped on a bird that walked away - did not fly.  It was black - or dark - thin - small to mid-sized - looked like a small chicken.  Slightly smaller than a robin, but much skinnier.  It walked with the line of beak-thru-rear held horizontal - not upright.  The lower backside was white, but I don't think this extended to the belly.  The stubby tail-feather were held upright, thus making the white area obvious.  My camera was not handy, so picture not available.  Certainly not a White-tailed Ptarmigan - it was smaller, much skinnier - and mostly black.

  The only thing that came to mind was a Black Crake - except they have different overall coloration, and live at low elevation wet areas in Africa, not a likely candidate.

  I would believe it was a member of the rail family.  Seemed bigger than a Black Rail, perhaps a Virginia Rail that got lost?

  Birder friends who are better than I have seized on the idea that I was hallucinating, but I was not.    

[Benjamin]

Likely a young/recently fledged bird. Certainly not a rail at 12800 feet.

[Phalarope713]

Yeah, definitely not a rail. Young White-tailed Ptarmigan sounds like a good match. You usually don't fine Dusky Grouse on the alpine.