BLUE OR METALLIC BLUE 507 
at San Diego flying out after insects, or skimming the 
air like swallows, and hovering like hummingbirds. 
They have a pretty fashion of quivering their wings a 
moment as if loath to close them. 
Their song is a sweet clear “ trually, tru-al-ly,” like 
that of the Eastern species, and a mellow warble. High 
up in the mountain meadows, where these bits of azure 
nest, they are usually seen only in pairs, and are fre- 
quently the only pair in the neighborhood, and here their 
feeding habits are those of the thrushes once more. 
Both male and female carry material to the old tree 
which they have selected for a home. Usually the 
cavity chosen is one excavated the previous year by a 
woodpecker, but sometimes a natural hole in a dead tree 
or a crevice about a house is selected. In any case it is 
nearly filled with dried grass and feathers. Fourteen 
days are required for incubation, and in this the male 
often, but not always, shares. When not on the nest 
himself he brings food to his mate, calling to her in 
sweetest tones from the outside before entering the door- 
way. The newly hatched young are of the usual naked 
pinkish gray type, looking as like tiny new-born mice as 
birds. On the second day down begins to appear in 
thin hairs on head and back; on the fourth or fifth day 
the eyes show signs of opening; on the sixth day they 
open, and the down is well spread over the bodies. 
Up to this time they have been fed by regurgitation, 
the adult swallowing each bit first to moisten or crush 
it; but from the fourth day on fresh food is given occa- 
sionally, and from the sixth or seventh day all the food 
