LIFE HISTOKIES OF NORTH AMERICAN DIVING BIRDS. 31 



bating by many observers. I believe that they all incubate regularly, 

 particularly at night and during inclement weather. The eggs are 

 covered with the nesting material purely for concealment. I have 

 no doubt that on bright, warm days the eggs are frequently left for 

 long periods, when the heat of the sun helps to continue the hatching 

 process; perhaps on very hot days the covering of w^et rubbish may 

 protect the eggs against too intense heat. There are numerous cases 

 on record where eggs have been killed by too much heat, during a pro- 

 tracted hot spell. Mr. William G. Smith reported, in his notes sent 

 to Major Bendire, two such cases in Colorado, where the thermom- 

 eter registered 108 in the shade during the nesting season ; the nests 

 which were in open situations suffered most severely; he said that 

 during the heat of the day the birds did not seem to be able to sit 

 on their nests in the hot sun and practically all of the eggs were 

 destroyed. 



Young. — Mr. Eobert B. Rockwell (1910) gives us the following 

 good account of the behavior of young grebes : 



A baby grebe half the size of a chick can swim as fast as a man can wade 

 througli the water comfortably, and the distance they can swim under water at 

 this tender age is surprising. They hide very effectively by diving and coming 

 up to the surface under tiny bits of floating moss or rubbish, where they lie 

 perfectly still with only the tips of their tiny bills exposed above the water. 

 Their feet are abnormally large, which probably accounts for their remarkable 

 swimming ability, and when quiet in the water the feet and head float on the 

 surface, the rest of the body being submerged. The only note of the young 

 grebe is very similar to the " cheep " of the domestic chick, first heard when the 

 egg is pipt — very weak and tiny at first, but growing in strength and power as 

 the bird becomes larger, until by the time the young are three-fourths grown the 

 note is quite loud and clear. 



The young birds have a peculiar habit of riding on the back of the parent 

 birds. This is apparently done for the purpose of imaginary protection to the 

 young, as we only observed it when broods of young were surprised close to the 

 shore, and were seeking safety in the middle of the lakes. At such times the 

 parent would swim close alongside the young bird and by raising the fore 

 part of the body out of the water would submerge the posterior portion, upon 

 which the youngsters would scramble with alacrity. The wings of the parent 

 were then raised something after the fashion of a brooding hen, and often 

 several babies would be cuddled comfortably beneath them. It was quite comical 

 to see a well-laden parent bird attempt to take on an additional chick, as this 

 often precipitated the entire brood into the water, and this was always the 

 signal for a wild scramble back on "board ship," during which rather strenuous 

 performance the doting parent was the victim of an animated mauling. This 

 additional weight on the parent's back did not seem to affect their swimming 

 powers, and the speed with which a mother grebe carrying a half a dozen 

 babies could leave danger behind was surprising. 



Plumages. — The downy young is glossy black on the back with a 

 few brownish or grayish longitudinal stripes anteriorly ; the head is 

 dusky, more or less striped or spotted with whitish ; the under parts 



