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BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 89
With this in mind, the following brief synopsis of my findings as to
the valid forms and their distribution will be clear.
CATHARTES AURA AURA (Linnaeus).
Vultur aura Linnaeus, Syst. Nat., ed. 10, vol. 1, 1758, p. 86. (State of
Vera Cruz, Mexico."*)
The typical form of the turke}^ vulture has the wing coverts dis-
tinctly margined with brown like C. a. se2)te7ifrionalis, but is smaller
as the measurements of the wing range from 475 to 510 mm. It
ranges from Panama (Empire, Fort Lorenzo) northward into Mexico,
and in the West Indies. Swann'^^ has described the bird from
Cozumel Island as C. a. insularis. From the description this is ap-
parently similar in size to au7'a (wing 470-505 mm.), but is said to
be darker. As Cozumel Island lies only 15 miles from the main-
land, I am inclined to consider this as doubtfully distinct (no specimens
are at hand), and for the present a synonym of aura, espe-
cially since there is some variation in degree of blackness in that
form. The type of Gathartes hurrovianus Cassin^* has been examined
by Nelson and pronounced identical with aura.
CATHARTES AURA SEPTENTRIONALIS Wied.
Cathartes septentt-ionali-s "NVied, Reise Nord-America, vol. 1, 1839, p. 162.
(Near New Harmony, Indiana.)
The northern turkey vulture is similar in color to typical aura,
but is larger, with a wing ranging from 520 to 553 mm. It ranges
from the northern part of the Mexican table-land north through the
United States into southern Canada. The southern limit attained
by this form in Mexico is uncertain,
CATHARTES AURA RUFICOLLIS Spix.
Cathartes ruficollis Spix, Avium Spec. Nov. Brasiliam, vol. 1, 1824, p. 2.
(Interior of Bahia and Piauhy.)
The turkey vulture of eastern and northern South America is
similar in size to typical aura, as the wing ranges from 495 to
510 mm., but differs in blacker color and in restriction of the brown
edgings on the wing coverts. It ranges from Paraguay (probably
from northern Argentina and Uruguay) north through Brazil into
the Guianas and Venezuela. The applicability of the name ruficollis
to the red-headed turkey vulture is discussed under the account of
the yellow-headed vulture. Hellmayr ^'^ has stated that Spix's type
of ruficollis was no longer extant, and referred the name to aura
with a query. I think there can be no valid reason for not recog-
*^Type locality fixed by Nelson, Proc. Biol. Soc. Washington, vol. IS, Apr. 18, 1905,
p. 124.
««Syii. Accipitres, ed. 2, pt. 1, Sept. 28, 1921, p. 3.
" Proc. Acad. Nat. Sci., Philadelphia, vol. 2, 1845, p. 212.
s^Abhandl. K. Bayerischen Akad. Wiss., II Klass. vol. 22, pt. 2, 1906, p. 567.