348 PALCO EICHAEDSONII, AMERICAN MERLIN. 



Falco eolumbarius, Cass., B. N. A. 1858, 9 (partly). 



Falco (Sypoiriorchis) richarilsonii , Eidgw., Pr. Phila. Acad. 1870, 145 ( g type one of Dr. 



Hayden's specimens). 

 SypotriorcMs richardsoni, Snow, B. Kans. 1873. 

 Falco riehardsoni, CouES, Key, 1872, 214. 

 Falco {JEsalon) lithofalco var. richardsoni, Eidgw. — B. B. & E., N. A. B. iii, 1874, 148. 



Sab. — Interior of Nortli America. United States from the Mississippi to the Rocky 

 Mountains. Arctic America. 



lAentenant JVumn's Expedition. — 5170-1, mouth of Vermilion Eiver, Dakota. 



Later Expeditions. — 58983, Berthoud's Pass; 60385, La Bont^ Creek, Wyoming; 60617, 

 Box Elder Creek, Utah; 60618-9, Green Eiver, Wyoming; 60620, Sweetwater. 



This species was first noticed by the authors of the Fauna Boreali- 

 Americana, who accurately distinguished it from the common Pigeon 

 Hawk, considering it identical with the F. cesalon of Europe. Subse- 

 quent writers attributed this last to North America, all apparently 

 having the j)resent bird in view. Mr. Cassin, with some of the speci- 

 mens before him that afterward served as the basis of Mr. Eidgway's 

 descriptions, noticed the discrepancies presented on comparison with 

 the ordinarj' F. columharius, but made no specific discrimination, citing 

 F. cesalon. of Swainson and Eichardson as a synonym. I observed the 

 same thing in 1866, remarking as follows : " In the immense series of 

 Pigeon Hawks which I have examined from all parts of the West, I 

 find a few specimens which constantly differ to a marked degree from 

 any of the diverse plumages in which F. columbarim presents itself. 

 These specimens are invariably much larger than any others in the 

 series; are much lighter colored ; and differ constantly in the increased 

 number of light and dark bars on the tail. Compared with a European 

 specimen of F. cesalon, they agree in every particular. I think it most 

 probable that future careful research will demonstrate the existence of 

 a species hitherto usually confounded with F. columhariusP This sur- 

 mise has been verified by Mr. Eidgway, who, however, has pointed out 

 some differences, before overlooked, between our bird and the true 

 cesalon, and proposed the specific name I have adopted. The bird may 

 prove, I still think, only a geographical race of cesalon ; in fact Mr. 

 Eidgway has latterly reducetl it. As the species is still very little 

 known, the description is subjoined.* It should be diligently sought 

 for in the northwest, additional specimens being very desirable. 



* "Adult male: Upper plumage, dull earth-brown, each feather grayish-umber cen- 

 trally, and with a conspicuous black shaft-line. Head above, approaching ashy-white 

 anteriorly, the black shaft-stresks being very conspicuous. Secondaries, primary- 

 coverts, and primaries, margined terminally with dull white ; the primary-coverts with 

 two transverse series of pale ochraceous spots ; primaries, with spots of the same, cor- 

 responding with those of the inner webs. Upper tail coverts, tipped and spotted be- 

 neath the surface with white. Tail, clear drab, much lighter than the primaries, bnt 

 growing darker terminally, having basally a slightly ashy cast, crossed witli six 

 sharply defined perfectly continnous bands (the last terminal) of ashy-white. Head 

 frontally, laterally and beneath — a collar round the nape (interrupting the brown 

 above) — and entire lower parts, white, somewhat ochraceous, this most perceptible 

 on the tibise ; cheeks and ear-coverts with sparse, fine, hair-like streaks of black ; 

 nuchal collar, jugulum, breast, abdomen, sides and flanks, with a median linear stripe 

 of clear ochre-brown on each feather; these stripes broadest on the flanks; each stripe 

 with a conspicuous black shaft-streak; tibise and lower tail-coverts with fine shaft- 

 streaks of brown, like the broader stripes of the other portions. Chin and throat, 

 only, immaculate. Lining of the wings spotted with ochraceous-white and brown, in 

 about equal amount, the former in spots approaching the shaft. Inner webs of pri- 

 maries with transverse broad bars of pale ochraceous — eight on the longest. Wing, 

 7.70; tail, 5.00; cnlmen, 0.50; tarsus, 1.30; middle toe, 1.25; outer, 0.85; inner,0.70; 

 posterior, 0.50. 



"Adult female : Differing in coloration from the male only in the points of detail. 

 Ground-color of the upper parts clear grayish-drab, the feathers with conspicuously 

 black shafts ; all the feathers with pairs of rather indistinct rounded ochraceous spots, 

 these most conspicuous on the wings and scapulars. Secondaries crossed with three 



