The shadows of the two men are not the only ones that move over the sunlit face of the artemisia.

There, too, are outlined the wings of birds--large birds with sable plumage and red naked necks, whose species both know well.
They are _zopilotes_--the vultures of Mexico.
A score of such shadows are flitting over the sage--a score of the birds are wheeling in the air above.
It is a sight to pain the traveller, even when seen at a distance.

Over his own head it may well inspire him with fear.

He cannot fail to read in it a forecast of his own fate.
The birds are following the two men, as they would a wounded buffalo or stricken deer.

They soar and circle above them, at times swooping portentously near.