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THE LIBRARY OF THE

JUL301940
UNIVERSITY OF ILLINOIS

ZOOLOGICAL SERIES

OF

FIELD MUSEUM OF NATURAL HISTORY

Volume 24 CHICAGO, JUNE 29, 1940 No. 15

A NEW SAVANNAH SPARROW FROM MEXICO

BY SIDNEY CAMRAS

While examining the Savannah sparrows in Field Museum with
reference to the recent revision by Peters and Griscom, I found
four summer specimens from west-central Chihuahua, where the
species was not known to breed. The birds were unlike any of the
North American forms, and agreed most closely with descriptions
of brunnescens, the race of south-central Mexico. Shortly after-
wards, Mr. A. J. van Rossem visited the Museum and, upon examin-
ing the specimens, suggested that comparison with brunnescens might
show that they represented a new subspecies. This comparison has
been made, through the courtesy of the authorities of the United
States Biological Survey and Field Museum, who arranged a loan of
the Survey's series of brunnescens. The Chihuahua birds prove to be
different and may be called

Passerculus sandwichensis rufofuscus subsp. nov.

Type from Babicora, Chihuahua, Mexico. No. 13076 Field
Museum of Natural History. Adult female. Collected June 15, 1902,
by G. F. Breninger.

Diagnosis. — Nearest to Passerculus sandwichensis brunnescens
Butler, but with the brownish tones brighter throughout and the
black markings heavier. Distinguishable from all the members
of the genus by its bright coloration.

Range. — Known only from the type locality.

Measurements. — Two males: wing (chord) 70.0, 71.2; tail 49.7,
50.0; tarsus 20.5, 20.5; exposed culmen 11.1, 10.7; depth of bill 5.9,
6.0. Two females (type in parentheses): wing (chord) (64.5), 65.0;
tail (45.5), 43.8; tarsus (20.4), 20.0; exposed culmen (11.1), 10.0;
depth of bill (5.8), 5.9.

Remarks. — Exactly how the new race differs from the recently
described wetmorei van Rossem, of Guatemala, can only be deter-
No. 475 159

160 FIELD MUSEUM OF NATURAL HISTORY— ZOOLOGY, VOL. 24

mined by direct comparison, but from the dorsal similarity of
wetmorei and alaudinus Bonaparte (i.e. bryanti Ridgway) the present
form must be lighter and brighter in coloration.

The long tail ascribed to brunnescens by Oberholser (Sci. Pub.
Cleveland Mus. Nat. Hist., 1, p. 110) on the basis of the measure-
ments published by Ridgway is not supported by my measurements,
which are as follows:

Males Wing Tail

brunnescens 15 70.69 48.31

nevadensis 17 69.45 48.43

anthinus 14 71.82 50.46

The discovery of a bird geographically between brunnescens and
nevadensis and yet showing no signs of intergradation is rather
unexpected. Where the new bird meets nevadensis, from which it
is so distinct, if it does so at all, would be very interesting.

Through the courtesy of Professor C. W. G. Eifrig, two specimens
of brunnescens in fresh breeding plumage, lent to him by the Car-
negie Museum, have been examined. Miss Ruth Trimble has
kindly furnished the data of several other Mexican Savannah spar-
rows in the Carnegie Museum. Dr. H. C. Oberholser and Mr.
R. T. Moore also have sent information for which I am grateful.

Thanks are particularly due to Mr. van Rossem, who examined
the material upon which this paper is based, and supplied much
information on types and relations of members of this group.

1HE UBWW OF THE

JUL301940

UNIVERSITY OF ILLINOIS

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