A History of North American Birds, Land Birds. Volume 3. Robert Ridgway
middle toe, .80. Outer tail-feathers and inner webs of the primaries with the white less in extent than the brown (never continuous along outer webs of the primaries). Hab. Middle America, and Western Province of North America … var. hypogæa.
B. Primaries without broad or regular bars of whitish on either web; primary coverts plain brown.
Brown markings on the lower parts regularly transverse, and equal in extent to the white. White spots on the upper parts very small, reduced to mere specks on the dorsal region.
Wing, 6.40; tail, 3.40; culmen, .60; tarsus, 1.82; middle toe, .85. Outer tail-feathers and inner webs of the primaries with the light (ochraceous) bars only about one fourth as wide as the brown (disappearing on the inner quills). Hab. Guadeloupe … var. guadeloupensis.38
Strix hypogæa, Bonap. Am. Orn. I, 72, 1825. Athene hypogæa, Bonap. Consp. Av. p. 39, 1850.—Woodh. (Sitgr.) Expl. Zuñi and Colorado, p. 62, 1853.—Cass. Birds N. Am. 1858, 59.—Newb. P. R. R. Rept. VI, 77, 1857.—Coop. & Suck. P. R. R. Rept. XII, ii, 157, 1860.—Gray, Hand List, I, 52, 1869. Speotyto cunicularia, var. hypogæa, (Ridgway) Coues, Key, 1872, 207. Strix cunicularia (not of Molina!), Aud. B. Am. pl. ccccxxxii, 1831; Orn. Biog. V, 264; Synop. p. 22.—Nutt. Man. Orn. p. 118, 1844.—Bonap. Am. Orn. p. 68, pl. vii, f. 2, 1825; Ann. Lyc. N. Y. II, 36.—James. (Wils.), Am. Orn. IV, 30.—Say, Long’s Exp. Rocky Mts., II, 36, 200. Ulula cunicularia, Jard. (Wils.) Am. Orn. III, 325, 1832. Athene cunicularia, Bonap. List, p. 6; Consp. Av. p. 38. Strickl. Orn. Syn. I, 160, 1855.—Cassin, Birds N. Am. 1858, 60.—Coop. & Suck. P. R. R. Rept. XII, ii, 157, 1860.—Canfield, Am. Nat. 1869, 583 (habits). Strix californica, Aud. B. Am. pl. ccccxxxii, 1831. Athene socialis, Gamb. Pr. Acad. Nat. Sc. Phil. III, 47, 1846.
Sp. Char. Adult. Above earth-brown, the whole surface covered with numerous spots of dull white,—those on the scapulars roundish, and in pairs (on both webs); of similar form, but larger and more sparse, on the wings. Anteriorly they become more longitudinal (nearly linear), and medial; on the rump and upper tail-coverts, they are nearly obsolete. Secondaries crossed by four distinct bands of dull white, the last terminal; primaries with five to six transverse series of semi-rounded spots of ochraceous-white on their outer webs; primary coverts with about three transverse series of whitish spots. Tail with five to six bands of dull white, or pale ochraceous (the last terminal), composed of transverse oval spots, those on the middle pair of feathers not touching either the shaft or the edge. Ear-coverts uniform brown, becoming gradually paler beneath the eye and on the cheeks; eyebrows, a transverse chin-patch,—covering the whole chin and jaw and reaching back beneath the auriculars, and another across the jugulum, immaculate cottony-white; shafts of the loral bristles blackish; a broad, well-defined collar across the throat, between the white malar and jugular bands, deep brown, mixed with paler spots.
Beneath white with a faint ochraceous tinge, especially on the legs; the breast, abdomen, and sides with transverse spots of brown, this often predominating on the breast; legs, anal region, and crissum, immaculate. Whole lining of the wing immaculate creamy-white, the primary coverts, however, with large terminal spots of dusky; under surface of the primaries grayish-brown, deeper terminally, and with large, transversely ovate spots of ochraceous-white (about five in number on the longest quill), and growing larger basally.
♂. Wing, 6.40–7.00; tail, 3.00–3.30; culmen, .55–.60; tarsus, 1.50–1.70; middle toe, .80. (Smallest, No. 5,183, Fort Pierre, Nebraska; largest, No. 6,881, Sacramento, California.)
♀. Wing, 6.50–6.80; tail, 3.15–3.30; culmen, .51–.55; tarsus, 1.50–1.60; middle toe, .80. (Smallest, No. 45,020, Laredo, Texas; largest, No. 3,971, San José, Lower California.)
Juv. Upper surface earth-brown, as in the adult, but entirely uniform, except the wings and tail; upper tail-coverts, and a large oval patch on the wing (covering the middle coverts and the posterior half of the lesser-covert region), plain isabella-white; the anterior portion of the lesser-covert region darker brown than the back. Gular region well-defined pure white; jugular collar conspicuous and unspotted. Whole lower parts immaculate isabella-white.
Hab. Western Province of United States, from the Plains to the Pacific, and from the Rio Grande to Cape St. Lucas; Mexico.
Localities: Xalapa (Scl. 1857, 290); Texas (Dresser, Ibis, 1865, 330; resident).
Specimens never vary in the pattern of coloration, and but little in the relative amount of the brown and white spotting; the shade of the brown and the depth of the ochraceous tinge vary considerably, however, in different individuals,—but irrespective of locality,—the brown being paler and the white purer in summer than in fall and winter, after the new dress is freshly assumed. The brown on the breast varies considerably in quantity, being sometimes nearly uniform, thereby abruptly contrasting with the white jugular band, and again frequently with the brown hardly greater in amount than the white, the two colors being in regular bars, as on the sides and flanks.
There is certainly but one species, or even race, of Burrowing Owl in North America. This is represented in the Smithsonian collection by over fifty specimens, including examples from all parts of its range. Upon a close inspection of all the specimens in this extensive series, I was very much surprised to find so little variation; indeed, all the specimens are so much alike that a detailed description of the colors of one would answer for almost any individual. The shade of color varies mainly according to the age of the feathers, those newly acquired having a darkness of tint and a softness of texture not seen in those more worn (as in midsummer dress), which have a bleached or faded appearance. I fail entirely to detect the different styles of plumage which Mr. Cassin has described, and his diagnoses of two supposed species will not at all hold good when applied to specimens from either of the two regions which they were considered to characterize.
Examining critically the large series at my command, I find that the principal discrepancy among individuals is the amount of feathering on the tarsus; this extending to the toes was supposed to characterize the A. cunicularia of North America the habitat of which was considered as restricted in North America to the west of the Rocky Mountains (see Cassin, Birds of North America, as cited above); the nearly naked tarsus was believed to be characteristic of the A. hypogæa, as restricted, and the habitat assigned to this was “from the Mississippi River to the Rocky Mountains.” Now, dividing the series under examination into two sets, according to this feature, we have, first, cunicularia from the following localities: from the Rio Grande, all specimens but one; Tongue River, Montana; and Petaluma, Santa Clara, and San Francisco, California. Next, hypogæa represents the following localities, besides places within the range ascribed to it: Utah; Lower California, including Cape St. Lucas, all specimens; San Diego, California, several specimens; Santa Barbara, San Francisco, Sacramento, and Fort Tejon, California; and Tamaulipas, Mexico.
Though we have but one species or form in North America, the South American bird is different: this is the true cunicularia of Molina, and though not specifically distinct from our bird, is nevertheless an easily recognized geographical race. It is larger, the wing measuring from 7.00 to 7.50, instead of 6.40 to 7.00; the brown of the plumage is appreciably darker than that of most specimens of hypogæa, but less extended; on the outer web of the primaries the white spots are larger,—sometimes confluent along the edge,—and on their inner webs the white largely prevails, the dusky bars appearing only towards the ends; the outer tail-feather is almost wholly white, instead of having brown bars, broader than the white ones. Of the var. cunicularia there are eight specimens in the collection (chiefly from Paraguay, Buenos Ayres, and Chile), while numerous others, in various collections, have been examined besides. All the American forms of this subgenus seem clearly referrible to one species, as being at the most but geographical races.
Habits. The Burrowing Owl of North America inhabits the country between the Pacific coast and the Mississippi River, especially in the lower plains in Nebraska and in Kansas, as well as in particular districts in Utah, Arkansas, New Mexico, the Indian Territory, Texas, Arizona, California, and Mexico. They are usually very abundant, congregating together