24 BULLETIN 113, UNITED STATES NATIONAL, MUSEUM. 



Although the adults of the long-tailed jaeger are not known to 

 have light and dark phases, there seem to be two quite distinct 

 types of coloration in the juvenal plumages. In the dark phase the 

 upper parts are dark "brownish black," or "clove brown ; the 

 head, neck, and chest are mainly dusky, the latter mottled with 

 "wood brown"; the feathers of the back and wing-coverts are 

 edged with " cinnamon " or " wood brown," and the rump is spotted 

 with the latter color; the lower parts are mainly buff, mottled and 

 barred, chiefly on the sides and under tail-coverts, with dusky. In the 

 light phase the upper parts are much the same as in the dark phase, 

 but much lighter colored, and the pale " wood brown " edgings are 

 broader and more prevalent ; the head and neck are mainly " pinkish 

 buff " and the crown is but little darker ; the head is uniformly cov- 

 ered with linear streaks of pale dusky; the under parts are largely 

 whitish, tinged with pale "pinkish buff," nearly immaculate on 

 the breast and belly, but heavily barred on the sides and under tail- 

 coverts with dusky. These descriptions are taken from young birds, 

 collected early in August, in full, fresh, juvenal plumage. Other 

 specimens taken late in September show similar well-marked color 

 phases, but birds a year older do not seem to show them. This plum- 

 age is worn, with slight modifications, during the first year; the 

 brown edgings fade out to white and gradually wear away; prob- 

 ably a partial molt occurs during the winter and spring. At the 

 first postnuptial molt, the following summer, a complete change 

 produces the second-year plumage. In this plumage the upper parts 

 are much as in the adult, except that there is only a trace of the 

 yellow on the sides of the head, often none at all; the two central 

 tail feathers now project decidedly beyond their fellows, which was 

 hardly noticeable in the previous plumage; but the under parts are 

 more or less barred with dusky, particularly on the flanks and chest, 

 and heavily so on the under tail-coverts. This plumage is worn for 

 about a year or so until the second postnuptial molt, which is com- 

 plete, beginning in June and lasting through September. At this 

 molt the long central tail feathers and the dusky under tail-coverts 

 are assumed ; the young birds then assume the adult plumage when a 

 little over 2 years old. 



Adults have a partial prenuptial molt in the early spring and a 

 complete postnuptial molt in August, September, and October. 

 The seasonal changes in adults are not conspicuous, though freshly 

 molted birds in the fall have the chin, throat, and neck clouded 

 with light drab and the dark crown less pronounced than in the 

 spring. The characters by which this and the foregoing species can 

 be recognized are somewhat involved and confusing; so, rather than 

 discuss them here, I would refer the student to Dr. L. StejnegerV 

 (1885) excellent remarks oh the subject. 



