158 



THE CONDOR 



Vol. XX 



In two of the sets the eggs were all individually embedded in the baked 

 earth to a depth of one-eighth to one-fourth of an inch, evidently having set- 

 tled when the surface of the ground was reduced to soft mud by rain-water col- 

 lecting in the slight depressions. As the ground dried the eggs were fixed in a 

 perfect mould or matrix, from which they could not roll. In fact they could 

 hardly be disturbed at all by the sitting birds. The only nesting material was 

 a small quantity of fine, dry rootlets and dead ' ' crowns ' ' of gramma grass, the 

 eggs in some instances being slightly embedded in this lining. As it is also 

 present in all other depressions on the prairie it is highly probable that here as 

 elsewhere it was deposited about the eggs by the wind and not through the 

 agency of the birds themselves. (See figure 25.) The protective coloration of 



Fig. 25. Eggs and nest of Mountain Plover, as photographed May 20, 1917, about 



TWENTY MILES EAST OF DENVER, COLORADO. EACH EGG HAD SETTLED IN THE SOFT MUD 

 WHICH WHEN DRIED FORMED A PERFECT MOULD OR CAST FROM WHICH IT COULD NOT ROLL. 



the nest and eggs, as well as of the rear view of the birds themselves, even 

 when in motion, is unsurpassed. In no instance, except one hereinafter noted, 

 was the bird seen to leave the nest, nor was any nest found except in the im- 

 mediate vicinity of moving birds. 



The site of the first pair of birds located and worked on May 13, 1917, was 

 visited and carefully searched on three subsequent trips, always revealing one 

 or both birds in practically the same spot, but never the nest. 



On May 20, during a rain storm, we noticed two birds running at a dist- 

 ance of about thirty yards from the road. Stopping, four of us spent more than 



