This Mountain Plover Charadrius montanus was one of 287 seen
at the Turf Farm by H140 and H57, 11 miles west of Pearsall, Frio
County, Texas on December 25, 2013. Many of the birds were feeding in fairly close proximity to one another, and some of them exhibited a threat display whereby the tail was fanned and quivered almost constantly. CLICK HERE to see a short video clip of this behavior.
Another observation facilitated by this activity was that the upper tail coverts and tail appeared contrastingly gray on all the birds behaving in this manner - I've never noted this effect before, and I have previously obtained a number of good flight photos of this species - click here to see them (bottom of the page):