STEECOEAEIUS PAEASITICUS, PAKASITIC JAEGER. 613 



region, and whole upper parts, as in the adnlt. The under parts white (as in the 

 adnlt), but clouded everywhere with dusky patches, most marked across the brea--t, on 

 the sides, the flauks, and under tail coverts, and leaving the middle of the belly and 

 throat nearly pure. Varying degrees of this dusky uubilation approach in some speci- 

 mens neaily to the uniform dusky below characterized : in others fade almost into the 

 pure white of the adult, connecting the two ages perfectly. The tarsi of the most 

 dusky specimens have small yellow blotches ; the others nor. 



Dusiy stage {"So. 20362;. — With the size and proportions of the adult. Wholly deep 

 dusky ; darker and more plumbeous superiorly ; lighter, and with a fuliginous tinge, 

 inferiorly; the ijileum quite black; the latero-nuchal re^^'ion yellon'; the remige.^ and 

 rectrices quite black ; feet black. 



Immature (Xo. l-(>52j. — .Size and general proportions nearly those of the adult. BiU 

 and cere perfectly formed ; feet mostly black, but with some yellow blotches. The 

 upper parts are unadulterated with auy rufous bars ; the deep brosvnisb-black pileum 

 has appeared, and the sides of the neck have obtained their yellow shade, which con- 

 trasts conspicuously with the fuliginous background. Evidences of immaturity, 

 however, are found on the under parts, where the dark color is mixed with the illy- 

 defined transverse bars of ochraceous. Enfous is al.-o found at the bend of the wing 

 and on the under wing and tail coverts. The primaries are still whitish at the ont- 

 side, as are also the rectrices. The central rectrices project 2^ inches, and ha^ e the 

 tapering form of those of the adults. 



Younger (Xo. ■27.j4). — Tfle juvenility of the specimen is attested by its small ^ize, 

 delicate bill and feet, little projection of the central rectrices, general muUi pilose eou- 

 dition of plumage, &c. The rufous of the very youug bird, instead of giving way 

 everywhere to dusky, yields to this color only on the upper i)aLts and crown ; on the 

 sides of the head, neck, and the whole under parts, whitish being the predominating 

 color ; the continuity of this last being interrupted by indistinctly marked dn-ky bars. 

 The yellow of the sides of the neck has not yet appeared. There is the same white 

 space on the bases of the wings and tail that exists on the very young. The central tail 

 feathers only project about 2J inches. 



Toung-of-ihe.-ijear in August. — Size considerably less than that of the adnlt, form every 

 way more delicate. Wings more than an inch shorter ; bill and feet much glen.lere'r 

 and weaker. Bill in some specimens light bluish-horn ; in others greenish-olive, the 

 terminal portion brownish-black. Tarsi and greater part of the toes yellow. The 

 bird is everywhere rayed and barred with rufous and brownish-black. On the head 

 and neck the rufous has a very light ochraceous tinge, and is by far the predominating 

 color, dark only appearing as a delicate line along the shaft of each feather. There is 

 an aggregation of the brown into a spot at the anterior cauthus of the eye. Proceed- 

 ing down the neck to the back, the longitudinal lines become larger, and gradually 

 spread wider and wider, until between the shoulders they occupy the whole of each 

 feather, except a narrow border of rufous, which latter is of a deeper tint than on the 

 head. Passing down the throat to the breast, the rufous becomes decidedly lighter — 

 almost whitish — while the brown, which on the throat exists only as a light longitud- 

 inal line, changes on each feather to transverse bars of about equal width with the 

 light rufo'_s bar's with which it alternates. This pattern prevails over the whole under 

 parts, the transverse bands being broadest on the flanks aud under taU and wing 

 coverts, narrowest in the middle of the belly. The primaries are brownish-black, nar- 

 rowly tipped with rufous, their shafts yellouish, their inner webs fading basally into 

 white. • The tail has the same coloration as the wings. The central feathers project 

 about three-fourths of an inch. 



In this species we can favorably study the changes of plumage which are character- 

 istic of all the species. I am enabled by the extensive series at my command to trace 

 the various stages of the present species. 



Beginning with the stage last descnbed, that of the young-of-the-year, we find it 

 characterized essentially by the presence of rufous or ochraceous, disposed chiefly in 

 tramrerse bars, or spots, or waves, which alternate with similarly shaped dusky or 

 brownish-black markings. The birds are much smaller than the adnlts, the bill and 

 feet more delicate. As the bird grows older the bill and feet become stouter, the «ere 

 better developed, and the rufous everywhere grows first lighter and then more re- 

 stricted, giving way to an encroachment of the blackish. This increase of the darker 

 color is particularly rapid on the upper parts, which become tmifbrmly dustv before 

 the under parts do. When this has taken place the bird is in the plumage of Xo. li6.!.-2. 

 The tarsi and feet are still mostly yellow; there is stiU the white space at the leases of 

 the primaries ; the central rectrices still have only a partial development. By the 

 time the rufous mentioned in >.o. 166.52 as existing on the alar coverts, under parts, 

 tic, has entirely disappeared, the bird has become half-grown, and is now in that 

 peculiar state of plumage characterized in the description of No. 20362. This is a defi- 

 nite stage. Bnt some few specimens in the collection do not seem to pass through this 

 dusky epoch in arriving at maturity. The rufous yields to black only on the upper 

 parts ; on the under parts the blackish bars as well as the rufous ones become chan ■ d 



