i7o 
| Vol. VII 
The Pacific Nighthawk 
BY JOSEPH GRINNELL 
Chordeiles virginianus hesperis new subspecies. 
SubSPECIEIC Characters — Most nearly resembling Ch. v. virginianus , but: — outer surface 
of closed wing grayer toned; lower tail-coverts and feathers of belly region more narrowly and 
sparsely dark-barred; and, in the male, white patches on throat, wings, and tail more extensive. 
Type — $ adult; No. 6917 Coll. J. G.; Hear Lake, 6700 feet alt. , San Bernardino Mts., Califor» 
ilia; July 30, 1905; collected by J. Grinnell aud J. Dixon. 
Distribution — The race is based on 14 fresh specimens from the San Bernardino Mountains, 
California, where the species breeds in the Canadian Zone (7000-9000 feet), descending in its 
evening insect-hunts thru Transition (as low as 5000 feet). An example from Newport, Oregon, 
and several from the central Sierras (Amador and El Dorado Counties), California, are closely 
similar; so that it is probable that Ch. v. hesperis is the race visiting the whole Pacific Coast of 
the U; S. in summer, and breeding in the Canadian Zone from the San Bernardino Mountains 
northward. 
Remarks — Ch. v. hesperis is ecpial in size to the largest northern representa- 
tives of Ch. v. virginianus , that is, somewhat larger than examples of the latter 
race from Maryland and Virginia, and notably larger than the several races from 
the southern border of the U. S. In tone of coloration the male is much darker 
than in either Ch. v. sennetti or Ch. v. henryi. Altho somewhat lighter than vir- 
ginianus, this is in the direction of pale gray and white rather than ochraceous. 
The extended mottling of the otherwise blackish feathers dorsally is responsible 
for this lighter tone, and especially notable is the extensive silvery gray mottling 
on the wing coverts. Yet this dorsal tone does not nearly reach the paleness of 
sennetti. The decrease in width and numbers of the dark bars on the belly and 
crissum gives that portion of the lower surface a decidedly whitish cast, as in 
henryi. But instead of a great extension of ochraceous or tawnv dorsally as in the 
latter form, the brown tints are even less intense and extensive than in virginianus. 
The face region of hesperis is much paler than in virginianus , due to replacement 
of restricted deep tawny markings with larger ones of pale ochraceous. The same 
is true of the chest. The white patches on the throat, primaries, and rectriees of 
hesperis average decidedly larger. The patch on the outer primary invades across 
the shaft to include the outer web; and the same is observable of the patches on 
the tail-feathers. 
Many of the above remarks apply also to the female, except of course where 
sexual differences are involved. The female of hesperis is gray rather than tawny, 
and is thus at once distinguishable from the female of henryi. 
The nighthawks of the West deserve thoro overhauling. It is evident from the 
relatively scant material at hand that the name "henryi," as generally employed of 
late, is an aggregate, including at least three races. The birds breeding in portions 
of southern 'Texas are altogether different from those of Arizona and New Mexico 
(—henryi), while Rocky Mountain examples differ from both. I have seen no 
specimens of true henryi from California, and it is probable that all, or nearly all, 
of our references to henryi belong under the new name hesperis. Material is de- 
sirable from many localities — well-prepared skins, free from grease. Nighthawks 
are troublesome to save in good shape; and as I have lately learned, to give proper 
results a nighthawk skin demands about three times the time and patience that 
most any other bird does. 
I am under obligation to the United States National Museum, thru Dr. C. W. 
Richmond, Acting Curator of its Division of Birds, for the loan of a pertinent 
series of nighthawks. 
Pasadena , California. 
