Article XXI.— On the Color- Pattern of the Upper Tail-Coverts 
in Colaptes auratus. By Frank M. Chapman. 
Several years ago my attention was attracted by the wide range 
of variation shown in the color-pattern or pictura of the uppei 
tail-coverts of Colaptes auratus. Until the present time material 
to study this variation has not been available. Dr. Allen now 
places at my disposal the fine series of Colaptes which, through 
the assistance of fellow-naturalists, he has brought together for 
use in another connection. The variation in question occurs m 
all of the upper tail-coverts, and its nature may be understood by 
reference to the accompanying plate (p. 314) in which are figured 
the middle coverts alone. Figs. 1 and 2 represent the first stages 
in a series of patterns which terminate in Fig. 15. With few 
exceptions birds in first plumage agree with Figs. 1 or 2, which 
represent the amount of variation at one stage. Subsequent 
changes are apparently accomplished by the moult, and one 
moult may carry a bird through one or all of the stages figured. 
For example : No. 103,072 of the U. S. Nat. Mus. Collection 
(Warren Creek, Col., ? , Dec. 26, F. Ball) has nearly completed 
its adult plumage, but there remains of the first plumage one of 
the long upper tail-coverts intermediate in pattern between Figs. 
1 and 2, while the corresponding feather of the new plumage 
agrees very nearly with Fig. 12. Other examples in a similar 
stage of plumage show, as has been said, that the change from a 
barred to a longitudinally-marked feather is accomplished by one 
or more moults. The large proportion, however,— one-third— of 
adult birds agreeing with Figs. 1 or 2, and the frequency of intei- 
mediate phases, indicate a more or less regular advance by 
successive moults to the final stage. While in transition the 
smaller and more anterior coverts are as a rule slightly in advance 
of the ones posterior to them. The longest and most posterior 
feather, therefore, is the last to be affected, and the final result 
has not been achieved until this feather agrees with the ones 
before it ; for this reason it has been selected to represent the 
upper tail-coverts as a whole. The lower tail-coverts pass 
through a somewhat similar series of changes, which to a certain 
extent correlate with those presented by the upper tail-coverts. 
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