38 BULLETIN 107, UNITED STATES NATIONAL MUSEUM. 
The adult nuptial plumage, characterized by the slate-gray head 
and neck, with the clear black crown and throat, is often worn until 
October; and the time of the postnuptial molt varies greatly in 
different individuals. This molt is probably complete, though I have 
not been able to trace it fully. Sooner or later a winter plumage is 
acquired, which is not very different from the nuptial plumage, 
except that the lower parts are purer white and there is more or less 
white in the chin and throat; perhaps these are sometimes wholly 
white, but more often the black predominates. This adult winter 
plumage, which is very different from the first winter, is apparently 
worn from October to March, when a limited prenuptial molt pro- 
duces the spring plumage. 
Food.—Nothing seems to have been published on the food of this 
species except the following unsatisfactory note by Mr. Gosse (1847) : 
The gizzards of all that I obtained were filled with a finely comminuted sub- 
stance, rather dry, of an unctuous appearance, and mingled with short silky 
filaments. A close examination with a lens failed to determine its nature; but 
I believe it to have been principally vegetable. 
Behavior.—The same writer tells of their behavior: 
The ponds of the cattle pens are the favorite resorts of this little grebe. I 
have been most familiar with it at the pond of Mount Edgecumbe, which, 
though not more than an acre or two in extent, used to be speckled with a good 
number of these miniature ducks, their little black heads and the tops of their 
backs alone being visible above the surface. On the slightest alarm they dive 
with the quickness of thought, and so vigilant is their eye and so rapid their 
motion that, ordinarily, the fowling piece is discharged at them in vain. It is 
commonly said of some birds that they dive at the flash of the pan; but 
though I always used percussion locks I could never succeed in hitting one until 
I formed a screen of bushes, behind which I might fire in concealment. I then 
found no difficulty. Hence, I infer that their quick eye detects and takes alarm 
at the small but sudden motion of the falling hammer. They remain long and 
swim far under water, coming up where quite unlooked for. Some that I have 
had an opportunity of observing when swimming a little beneath the surface 
shot along with expanded wings, almost with the celerity of a fish. They do 
not always dive, however, when frightened; sometimes they sink deeper than 
before, and swim away almost submerged. When not alarmed they call and 
answer each other, with a loud clang, like the note of a trumpet. 
Winter.—The Mexican grebe seems to be a resident throughout 
the year in the regions which it inhabits. Its short wings hardly 
enable it to rise above the surface of the ponds in which it lives, so 
that it is incapable of, or poorly equipped for, long migratory flights. 
It seems to be perfectly content to spend-its life in the waters of its 
birth, where it is perfectly at home. Its plumage is so thoroughly 
impregnated with oil and its breathing apparatus is so specialized 
that it moves about in the bottom of the pond as freely as on land, 
living an amphibious life of ease and comfort and interested only 
in its watery surroundings. 
