LIFE HISTORY OF THE QUETZAL—SKUTCH 287 
of the lowlands. During the month it remains in the burrow, the 
nestling blue-throated motmot changes its color even more completely 
than the quetzal. At the age of 10 days, the little motmot, hatched 
naked, is already practically covered with loose, fluffy down, dark 
gray on the upper parts and tawny on the sides and flanks. When it 
it is 4 weeks old, its gray and tawny feathers are all covered over and 
concealed by green ones that develop more tardily. On quitting the 
nest, the young motmot closely resembles its parents, which are not to 
be distinguished from each other. The exact details of this change of 
coloration are slightly different in the motmot and the quetzal; but 
the general process of overlaying the dull feathers of precocious de- 
velopment with bright ones that expand later is the same in both. The 
turquoise-browed motmot of the hot regions undergoes no such altera- 
tion. The feathers do not begin to expand until about the twelfth day, 
and the nestlings in developing plumage at once display all the deli- 
cate beauty of the adults. I am familiar with no other bird, quite 
naked at birth, that changes the coloration of its plumage in this way 
during the period it remains in the nest. But it seems possible that 
in other tropical species which begin to acquire the adult colors soon 
after quitting the nest a similar process may occur. 
Since coloration in itself can be of no importance to the safety of 
a motmot in its nursery at the end of a long, dark tunnel, and is prob- 
ably of slight account with a quetzal in a deep cavity in a trunk, one 
wonders why the nestlings do not array themselves in their brightest 
hues at the very outset. It seems important to these highland nest- 
lings that they early acquire a downy vesture to protect them from 
the cold in their covered nurseries; but at the same time they guard 
their feathers of firmer texture from wear, keeping them enclosed 
within the horny sheaths until the date approaches when they will be 
needed; for upon quitting the nest, both the quetzal and the blue- 
throated motmot enter a rainy world. The contour feathers of firm 
texture, which are not needed until later, are those which bear the 
green color. The change of coloration while in the nest appears to 
be incidental, and not in itself of consequence, save as an indicator of 
other alterations. 
DEPARTURE OF THE NESTLINGS 
On the morning of August 1, when the young quetzals were 3 weeks 
old, I for the first time saw one of them stand on the sill of the door- 
way ; it looked out for a few minutes after the father had given it food. 
Two days later, I removed one of the young from its nursery and 
placed it on a mossy log beside me while I wrote a description of its 
plumage. At first it made no attempt to fly. (Neither of the nest- 
lings had tried to use its wing on past occasions when taken from the 
