286 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1946 
lower back and rump were dull black, but with green feathers coming 
in. The two central tail coverts were green, with black tips and brown 
subterminal spots; the remaining upper tail coverts were dull black, 
with a brown subterminal spot on the next to the middle pair. The 
tail feathers were still very short, but so far as visible the six central 
rectrices were dull black, whereas the outer three on each side had 
white vanes and black shafts. The wing plumes likewise were dull 
black, with buffy outer margins on all but the outermost, these becom- 
ing gradually more prominent on the inner secondaries. The wing 
coverts were black, variously margined with buff, except on the lesser 
coverts and the greater coverts of the primaries. 
Turning to the under parts, the chin and throat were tawny buff, 
with some green feathers just sprouting in on the foreneck. The breast 
was buff with scattered green-tipped feathers, the flanks paler buff, and 
the center of the abdomen nearly white. The bill was black, the irides 
brown, and the feet plumbeous. 
These two fledglings, of unknown sex, appeared very much the same 
as others I saw ata greater distance. Although they resembled neither 
parent, they were most like the female, from which they differed most 
conspicuously in the far smaller amount of visible green, the lighter 
color of the chest and upper abdomen, the absence of red on the belly 
and under tail coverts, and in many other less conspicuous particulars. 
It is instructive to compare the rate of feathering of the quetzal 
with that of other trogons. Baird’s trogon offers the most illuminat- 
ing comparison, since it has an approximately equal period of nest 
life. The feathering of the young quetzals began on their seventh 
day and by their fourteenth they were well covered. But at the age 
of 12 days, the nestling Baird’s trogon of the lowlands is still in pin- 
feathers. A day later, these begin to ravel off at the ends, exposing 
the true plumage. By its sixteenth day, the nestling is well clothed. 
Thus it is covered with feathers only a day or two later than the 
quetzal; but the shedding of the horny sheaths begins far later and is 
a much more rapid process. The same earlier escape of the feathers 
from their sheaths is evident in the Mexican trogon of the highlands 
as compared with the black-headed trogon of the lowlands. The con- 
tour feathers of the Mexican trogon begin to expand at the age of a 
week and the little birds are well feathered when 12 days old. When 
2 weeks old, young black-headed trogons bristle like porcupines with 
their long, unbroken pinfeathers; then a marvelously rapid trans- 
formation occurs and 2 days later they are well clothed and ready to 
fly from the nest. 
A similar acceleration of feathering in a cooler climate is revealed 
by the comparison of the highland blue-throated motmot (Aspatha 
gularis) with the turquoise-browed motmot (Zumomota superciliaris) 
