The Costa Hummer 
though they are not known to breed within a hundred miles. Northern 
“winter” records (really late fall) also exceed the breeding records by a 
degree or so. There is evidently some uncertainty attendant upon the 
autumnal retreat, and there are a number of desert or Lower Sonoran 
records for winter, but none for the breeding season. 
No. 185 
Costa’s Hummer 
A. O. U. No. 430. Calypte costae (Bourcier). 
Description. — Adult male: Head all around, with latero-posterior extension of 
throat feathers, metallic violet-purple, changing to velvety black or with light blue 
reflections; flight-feathers and lateral rectrices purplish dusky; remaining upperparts 
shining bronzy green (golden green or peacock-blue with changing angle of vision); 
dusky shading of underparts nearly confined to wing-linings; sides of breast and centers 
of lower tail-coverts (where overlaid with bronzy green) shading through buffy of chest 
to clear white in definition of gorget; femoral tufts and edges of lower tail-coverts white; 
tail double-rounded, the outermost feather very narrow. Bill straight, black; feet black. 
Adult female: Without metallic feathers on head, save for flecking very variable in 
extent on upper portion of throat; green of back as in male, but forehead and crown 
drab or grayish brown, a fainter tint of drab blending on sides of head and neck; under¬ 
parts nearly uniform dull buffy or sordid whitish; tail rounded (scarcely double-rounded) 
with colors and proportions as in C. anna. Young male: Much like adult female, 
but upperparts nearly uniform bronzy green, heavily margined with buffy; throat 
more heavily shaded and gorget of adult outlined, the metallic feathers first appearing 
on the lower portion of the throat. Young female: Like adult female, but drab of 
head more extensive, and throat unflecked. Length (sexes about equal); 85.1 (3.35); 
wing 44.4 (1.75); tail 22.6 (.89); bill 17.2 (.68). 
Recognition Marks. —Pygmy size; violet-purple gorget and crown of male 
distinctive; the female, although a little smaller, is nowise distinguishable in the field 
from that of A. alexandri. Indeed, the only certain distinction in hand is generic— 
C. costa lacks the curious tooth at the subterminal angle of the inner web of the inner 
primaries, which is the subtle birthmark of the genus Archilochus. A ready but by 
no means infallible field distinction is, however, afforded by the difference in nest 
structure (g. ».). 
Remark. —The nearly distinction-defying similitude of the females of Calypte 
costa and Archilochus alexandri ought to guard taxonomers against the folly of generic 
separation of these two groups. The males, to be sure, are strikingly, though quite 
superficially, divergent in two respects; viz., the invasion of the crown by metallic 
feathers (in the Calypte group) and the reduced inner primaries of the Archilochus 
group. But all distinctions in the case of the females reduce to a pitiful atom of a 
projection on the webbing of certain primaries (in Archilochus), —a fairy wisp of evi¬ 
dence which would scarcely serve to distinguish twins to their own mother. 
Nesting. — Nest: Of highly variable construction; typically a dainty cup of 
vegetable downs, decorated externally with yellow-sered or gray leaves and plant- 
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