CRITICAL NOTES ON THE SUBSPECIES OF THE SPOTTED OWL, STRIX OCCI- DENTALIS (XANTUS) IHt UMMN OF THE •’’•'JSCS- v, \KGS'tc. BY HARRY C. OBERHOLSER Of the Biological Survey, United States Department of Agriculture No. 2106. — From the Proceedings of the United States National Museum, Vol. 49, pages 251-257 Published July 26, 1915 Washington . Government Printing Office 1915 THt LWSA81 OF THE charges * 1S ^library Vie person - ts return to before nonsiWe for ^drawn on or lhe«. tnehlo dl5C1 phna.V we „rty. Gf> °' e ;t “n SU-ot f-o^; te5U ' * ilUUO.S ^J^J=f=====^ ....iv/FRS'f'f 1 , 161 - 0-1096 Digitized by the Internet Archive in 2017 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/criticalnotesonsOOober CRITICAL NOTES ON THE SUBSPECIES OF THE SPOTTED OWL, STRIX OCCI- DENTALIS (XANTUS) BY HARRY C. OBERHOLSER Of the Biological Surrey, United States Department of Agriculture No. 2106. — From the Proceedings of the United States National Museum, Vol. 49, pages 251-257 Published July 26, 1915 Washington Government Printing Office 1915 CRITICAL NOTES ON THE SUBSPECIES OF THE SPOTTED OWL, STRIX OCCIDENTALIS (XANTUS). By Harry C. Oberholser, Of the Biological Survey , United States Department of Agriculture. The four current subspecies of Strix occidentalism with the geo- graphical range apportioned to each, are as follows: STRIX OCCIDENTALIS OCCIDENTALIS (Xantus). Symium occidental Xantus, Proc. Acad. Nat. Sci. Phila., 1859, p. 193 (Fort Tejon, California). Southern California and northern Lower California. STRIX OCCIDENTALIS CAURINA (Merriam). Symium occidental caurinum Merriam, Auk, vol. 15, January, 1898, p. 40 (Mount Vernon, Skagit Valley, Washington). Southern British Columbia, south through western Washington and western Oregon to central California. STRIX OCCIDENTALIS HUACHUCAE Swarth. Strix occidentalis huachucae Swarth, Univ. Calif. Publ. Zool., vol. 7, No. 1, May 26, 1910, p. 3 (Huachuca Mountains, Arizona). Arizona, New Mexico, Colorado, and central western Texas. STRIX OCCIDENTALIS LUCIDA (Nelson). Symium occidental lucidum Nelson, Proc. Biol. Soc. Wash., vol. 16, November 30, 1903, p. 152 (Mount Tancitaro, Michoacan, Mexico). States of Guanajuato and Michoacan, Mexico. Each of these forms was originally described from a single specimen, and the species is still uncommon in museums. Recent collecting for the United States Biological Survey has resulted in the acquisition of eight adult specimens of Strix occidentalis huachucae , all in fine adult autumn plumage, six of them from New Mexico, the others from Arizona. The types of Strix occidentalis caurina and Strix occidentalis lucida are also in the Biological Survey collection; while in addition the United States National Museum possesses the type of Strix occi- dentalis occidentalis and another California specimen; one adult Strix occidentalis lucida from Guanajuato, Mexico; and a practically topo- typical example of Strix occidentalis huachucae. Through the kindness Proceedings U. S. National Museum, Vol. 49— No. 2106. 251 50157 252 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 49 . of Dr. Joseph Grinnell I have been able to examine the type of Strix occidentalis huachucae ; and Dr. Louis B. Bishop has obligingly sent two specimens from New Mexico, together with three from Arizona, and two of Strix occidentalis occidentalis from California. Through Mr. H. S. Swarth it has been made possible to borrow nine more specimens of Strix occidentalis occidentalis from California, which he had brought together for a further study of his Strix occidentalis huachucae. He, furthermore, very courteously offered the writer the use of his manuscript notes made with the view of publishing a sup- plementary account. The above material, altogether 31 specimens, including 2 in juvenal plumage, constitutes by considerable the largest series of birds of this species that has ever been available at one time. A careful study of these for the purpose of identifying specimens in the collection of the Biological Survey, compels some surprising as well as interesting conclusions, which seem worthy of printed record. The eight adult examples from New Mexico, together with the six from southern Arizona, represent what should be typical Strix occi- dentalis huachucae. This race, quoting the original description, 1 differs from Strix occidentalis occidentalis as follows: “ Similar to Strix occidentalis occidentalis (Xantus), but slightly smaller, and conspicuously paler; white markings more extensive and dark areas less deep toned.” An exhaustive comparison of this series of 14 adults from New Mexico and Arizona with typical Strix occidentalis occidentalis shows that all but one of the characters given to separate Strix occidentalis huachucae are merely individual. The difference of size is inconsider- able and inconsequential, as the appended measurements demonstrate; while the supposedly most important distinction, that of the lighter tone of the dark areas, appears in but five of the fourteen specimens, and many of the others are even darker than normal Strix occidentalis occidentalis ! A single bird from Tucson, Arizona (No. 84433, U.S.N.M), is the palest of the present series, being, in its light rufescent brown coloration, very much like the type of Strix occidentalis huachucae , but even lighter and more rufescent, with more tinge of ochraceous on the face and lower parts. A specimen from the Santa Rita Mountains (No. 241139, U.S.N.M.), some 30 or 40 miles south of Tucson is, however, as dark as the type of Strix occidentalis caurina, the supposedly darkest form of the species. Other examples from N ew Mexico are even darker. Thus, light rufescent birds like the Tucson specimen above mentioned, together with others nearly as light in ground color, from New Mexico and Arizona, are found geographically intermingled with dark birds, and must be considered, therefore, merely as representing a color phase. There is, likewise, nothing but individual variation in the 1 Swarth, Univ. Calif. Publ. Zool., vol. 7, No. 1, May 26, 1910, p. 3. NO. 2106. NOTES ON THE SPOTTED OWL—OBERHOLSER. 253 amount of dark mottling on the legs and feet of these specimens, so that this can not be a racial characteristic. The only characters, so far as we can discover, which will distinguish Strix occidentdlis hua- chucae from Strix occidentdlis occidentdlis are the larger white markings on scapulars, cervix, superior wing-coverts, and posterior lower parts; together with the paler, often whitish bars on wing-quills and tail- feathers. This increase of white is most conspicuous and most nearly constant on the scapulars, only average on the other parts; but taken altogether, seems sufficient for the recognition of the Arizona race as distinguished from that of California. Another subspecies described as Syrnium occidentale luddum from Mount Tancitaro, Michoacan, Mexico, by Mr. E. W. Nelson , 1 was diagnosed as follows: “ Darker and with much less yellowish buffy suffusion throughout than in S. occidentale ; white markings larger and clearer white.” The type is identical in all respects with a specimen from Taylor Creek, Socorro County, New Mexico, except for being not quite so dark above as the latter. As a matter of fact, most of the birds in the New Mexico and Arizona series are fully as dark as the type of Strix occidentdlis lucida, several of them even more deeply colored. Another Mexican example, from Guanajuato, is the same as Strix occidentdlis lucida from Michoacan, though somewhat lighter than the type, with almost immaculate white legs and feet and more restricted white markings on the upper surface. From others of the Arizona and New Mexico series it can not be distinguished. Since, furthermore, all the characters valid for the separation of Strix occi- dentdlis lucida from Strix occidentdlis occidentdlis are the same as those distinguishing Strix occidentdlis huachucae from Strix occidentdlis occidentdlis, it follows that Strix occidentdlis lucida and Strix occidentdlis huachucae are identical. Thus the name of the Arizona race becomes Strix occidentdlis lucida Nelson , 1 because this name has several years priority over Strix occidentdlis huachucae Swarth . 2 The above comparisons necessarily involved an examination of Strix occidentals caurina, from Mount Vernon, Washington. This was originally described 3 as differing from Strix occidentdlis occidentals principally by reason of darker general coloration and reduced white markings. The before-mentioned specimens from California prove beyond reasonable doubt that Strix occidentdlis caurina is a synonym of Strix occidentdlis occidentals, for all its peculiarities are to be found among these California birds. Many of the specimens of Strix occi- dentdlis lucida from Arizona and New Mexico are fully as dark above as is Strix occidentals caurina, and some are even darker; several are as dark below, with nearly the same amount of ochraceous suffusion 1 Proc. Biol. Soc. Wash., vol. 16, November 30, 1903, p. 152. 2 Univ. Calif. Publ. Zool., vol. 7, No. 1, May 26, 1910, p. 3. 3 Merriam, Auk, vol. 15, 1898, p. 40. 254 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 49 . posteriorly, and with practically an equal amount of mottling on the legs and feet. In the reduction of light markings on the upper surface the type of Strix occidentalis caurina may be closely matched in all respects by some of the California birds, as well as by the type of Strix occidentalis occidentalis. Moreover, the type of Strix occidentalis occidentalis is an old, formerly mounted specimen, and is considerably faded and apparently otherwise discolored. Another southern Cali- fornia example (No. 1392, collection of G. Willett) is actually identical with the type of Strix occidentalis caurina , except for being darker. There is thus no distinctive character left for the recognition of Strix occidentalis caurina as a subspecies. From what has already been said it is evident that there are but two forms of Strix occidentalis , instead of four, although both have a relatively wide geographical range. The only characters that now appear to be of value for the separation of these geographical races are in the size and distinctness of the white markings on the feathers, principally of the upper parts, though also below, but there is great variation even in this respect in the series of specimens examined. The following millimeter averages of birds from various regions throughout the range of the species, show clearly of how little sub- specific value is any difference of size : Localities. Wing. Tail. Exposed culmen. Culmen from cere. Tarsus. Four males (Strix occidentalis occidentalis ), from Cali- fornia mm. 309.8 mm. 202 mm. 30.9 mm. 20.9 mm. 52.5 Seven males (Strix occidentalis lucida ), from Arizona and New Mexico 307.1 199.9 29.8 20.3 53.1 Six females (Strix occidentalis occidentalis), from Cali- fornia 310.8 206.1 31.8 22.2 53.6 One female (Strix occidentalis occidentalis), from Wash- ington 304 198 31.5 21.3 54 Six females (Strix occidentalis lucida), from Arizona and N ew Mexico 312.7 206.1 31 21.3 53.4 Two females (Strix occidentalis lucida ), from central Mexico 311 203 30.6 21.7 54 This reduction of the four described and currently recognized sub- species of Strix occidentalis to two closely allied forms is a surprising conclusion, in view of the wide geographical range of the species — from central Mexico to southern British Columbia — and also of the well-known tendency of owls in general, to form numerous geographi- cal races, but it is inevitable from an examination of the material now available. The only other course possible is to reduce them to a single form. The present result is, however, nearly paralleled by the unexpected, but none the less apparently correct conclusion by Mr. Robert Ridgway 1 concerning the lack of any recognizable subspecies in Otus jlammeolus. It shows, too, that geographic or physiographic analogy, though of considerable assistance in working out geographical races, is an unsafe guide alone. 1 Bull. U. S. Nat. Mus., No. 50, pt. vi, April 8, 1914, pp. 728-730. no. 2106. NOTES ON THE SPOTTED OWL—OBERHOLSER. 255 Our investigation has resulted, furthermore, in the interesting dis- covery that there are two well-marked color phases in Strix occiden- talism the lighter of which is of comparatively rare occurrence. One of these phases is characterized above by a deep clove brown ground color, below by markings of similar color, and is represented by many of the specimens in the Arizona-New Mexico series, as well as by the types of Symium occidentale caurinum Merriam and Symium occi- dental lucidum Nelson. The other phase is rather light rufescent brown above, with similar markings below, and is exemplified by the specimen from Tucson (No. 84433, U.S.N.M.). Between these two phases there are various intermediates, represented in our series by the types of Strix occidental is occidentalis and Strix occidentals huachucae; several further examples from Arizona and New Mexico, and a specimen from Pasadena, California (No. 135190, U.S.N.M.). Another point, which the measurements bring out, and which seems worthy of notice, is that the female in this species is but little larger than the male, showing much less difference in this respect than is usual among owls. In view of the above conclusions, the races of this species will now stand as follows: STRIX OCCIDENTALIS OCCIDENTALIS (Xantus). Symium occidentale Xantus, Proc. Acad. Nat. Sci. Phila., 1859, p. 193. Symium occidentale caurinum Merriam, Auk, vol. 15, January, 1898, p. 40. Type-locality. — Fort Tejon, California. Geographical distribution. — Pacific coast region of the United States, in Washington, Oregon, and California; also north to southern British Columbia; south to northern Lower California; and east to eastern California. Measurements . * l — Male: Total length (in flesh), 436.9 mm.; 3 extent of wing, 763. 2 Female: Total length (in flesh), 431.8-489 (average, 463.6) mm .; 1 extent of wing, 104 1.4. 2 Male : 4 Wing, 301-322 (average, 309.8) mm.; tail, 200-204 (202); exposed culmen, 29.3-32 (30.9); culmen from cere, 20.5-21.2 (20.9); tarsus, 51-54.5 (52.5). Female : 5 Wing, 304-315 (average, 309.9) mm.; tail, 193-213 (204.9); exposed culmen, 30-33 (31.7); culmen from cere, 20-23.8 (22); tarsus, 53-54 (53.7). » Measurements in this paper are in millimeters, and have been taken as explained in the writer’s article on Butorides virescens (Proc. U. S. Nat. Mus., vol. 42, August 29, 1912, p. 533), except for “culmen from cere," which is the chord of the culmen taken from the tip of the maxilla to the anterior edge of the cere. * One specimen. 8 Three specimens. 1 Four specimens, from California. ® Seven specimens, from California and Washington. 256 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 49. Detailed measurements of the specimens of this race examined are as follows: Measurements of specimens of Strix occidentalis occidentalis. Museum and No. Sex. Locality. Date. Collector. CUD .9 £ Tail. 1 Exposed cul- | men. 1 Culmen from cere. Tarsus. L.B. Bishop 26195 1 Male Near Monrovia (alt., Nov. 3,1913 G. Willett. . . mm 311 mm 204 mm 31 mm 21.2 mm 51.5 G. Willett 1392 1 . . . . .do 2,500 ft.), Los Angeles Co., Cal. do Nov. 9,1913 do 305 201 32 20.5 53 U.S.N.M. 17200U . . ..do Fort Tejon, Cal. 2 J. Xantus. . . 322 203 31.3 21 51 U.S.N.M. 135190 i . ...do Pasadena, Cal Nov. 1,1894 W. B. Jud- 301 200 29.3 21 54.5 G. Willett 830i... Female . Fillmore, Ventura Dec. 13,1910 son. A. N. Stone. 305 193 31.3 22 54 L.B .Bishop 261961 ...do Co., Cal. do do do 315 203 32.8 22.5 53 C. H. Richardson ...do Wilson Peak Trail, Mar. 21,1905 C. H. Rich- 309 211.5 33 20 54 jr. 495.1 G. Willett 13931.. ...do Los Angeles Co., Cal. Near Monrovia (alt., Nov. 3,1913 ardson, jr. G. Willett... 315 208 31.8 23.8 53 L.H. Miller L. F. S. Daggett 45261 ...do ...do 2,500 ft.), Los An- geles Co., Cal. Castac Creek, Los Angeles Co., Cal. San Dimas Canyon, Apr. 10,1911 Feb. 14,1903 L. H. Miller. F. S. Dag- 310 311 213 208 30 22.5 54 U.S.N.M.157473 i. . ...do Pomona, Cal. Mount Vernon, June 22,1897 gett. E. A. Preble. 304 198 31.5 21.3 54 L. H. Miller .. Mus. Hist. Sci. Female, juvenal. Wash. 3 Forest Home, Cal Hills west of New- Aug. 17,1913 May 20,1906 L. H. MUler. H. J. Le- 310 203 31.3 20.5 53 Art . G. Willett 1395. .. hall, Los Angeles Co., Cal. Near Monrovia (alt., 2,500 ft.), Los An- geles Co., Cal. Nov. 3,1913 lande. G. Willett... 314 211 31 23 51.5 1 Used in measurement averages on p. 255. 2 Type of Syrnium occidental e Xantus. * Type of Syrnium occidentale caurinum Merriam. STRIX OCCIDENTALIS LUCIDA Nelson. Syrnium occidentale lucidum Nelson, Proc. Biol. Soc. Wash., vol. 16, November 30, 1903, p. 152. Strix occidentalis huachucx Swarth, Univ. Calif. Publ. Zool., vol. 7, No. 1 , May 26, 1910, p. 3. Type-locality . — Mount Tancitaro, Michoacan, Mexico. Geographical distribution. — Southwestern United States and north- ern and central Mexico ; north to Colorado; west to Arizona; south to Michoacan and Guanajuato; and east to western Texas, eastern New Mexico, and central Colorado. Chars, subsp. — Similar to Strix occidentalis occidentalis, but white markings on scapulars, upper wing-coverts, cervix, and posterior lower parts larger; light bars on remiges and rectrices more whitish. Measurements. — Male: Total length (in flesh), 419.1-444.5 (average, 434.3) mm.; 4 extent of wing, 1054.1-1073.2 (1065.3). 5 Female: Total length (in flesh), 419.1-457.2 (average, 441.5) mm; 5 extent of wing, 1041.4-1098.3 (1073. 2). 5 * Five specimens. 6 Four specimens. NO. 2106. NOTES ON THE SPOTTED OWL—OBERHOLSER. 257 Male: 1 Wing, 302-309 (average, 307.1) mm.; tail, 191-206 (199.9); exposed culmen, 27-32 (29.8); culmen from cere, 18.6-21.5 (20.3); tarsus, 52-54 (53.1). Female: 2 Wing, 302-320 (average, 312.3) mm.; tail, 196-212.5 (205.3); exposed culmen, 29-33 (30.9); culmen from cere, 19.5-23 (21.4); tarsus, 51.5-55.5 (53.6). Detailed measurements are added in the following table: Measurements of specimens of Strix occidentalis lucida. Museum and No. Sex. Locality. Date. Collector. | Wing. Tail. 1 Exposed cul- men. 1 Culmen from cere. Tarsus. H.S. Swarth 3691 3 . Male.... HuachucaMts.,Ariz. * Apr. 11,1903 H.S. Swarth mm. 308 mm. 193 mm. 29.5 mm. 20 mm 53 U.S.N.M. 241139 A. ...do Stone Cabin Canyon Oct. 28, 1913 V. Bailey. . . 309 205 29 20 53 L.B. Bishop 16876 s ...do (alt., 7,000 ft.), Santa Rita Mts., Ariz. Santa Catalina Mts., July 7,1906 H. Kimball. 302 191 32 21.5 53.5 L.B. Bishop 26164 3 ...do Ariz. Kelly Canyon (alt.. Mar. 23,1914 J. S. Ligon.. 307 201 27 20.5 53.5 U.S.N.M. 241186 3. ...do 6,500 ft.), western side of San Mateo Mts., Socorro Co., N. Mex. Head of Chloride Dec. 20,1913 do 309 201 30 18.6 53 U.S.N.M. 241183 8 . ...do.... Creek (alt., 8,000 ft.), 12 miles west of Chloride, Sierra Co., N. Mex. 6 miles west of Chlo- Oct. 22,1913 do 309 206 31 21 54 U.S.N.M. 240762 3. ...do ride (alt., 6, 500 ft.). Sierra Co., N. Mex. 15 miles northeast of Oct. 1,1913 do 306 202 30 20.5 52 L. B. Bishop 16878 U.S.N.M. 241184 3. Male,ju- venal. Female . Monticello (alt., 7,000 ft.), San Mateo Mts., So- corro Co., N. Mex. Santa Catalina Mts., Ariz. 3 miles north of Eagle July Dec. 7,1906 5,1913 H. Kimball. J. S. Ligon.. 315 206 31.3 20.5 54.5 U.S.N.M. 2411851 . ...do Peak (alt., 8,000 ft.), Tularosa Range, Socorro Co., N. Mex. Head of Chloride Dec. 20, 1913 do 309 208 30.8 21.8 52.5 U.S.N.M. 241138 a. ...do Creek (alt., 8,000 ft.), 12 miles west of Chloride, Sierra Co., N. Mex. Taylor Creek (alt., Nov. 3,1913 do 308 205 29 21.8 51.5 L.B. Bishop 26165 8 . ..do 7,000 ft.), 30 miles west of Chloride, Socorro Co., N. Mex. Bear Canyon (alt., Mar. 7,1914 do 320 212.5 32 21 53.5 U.S.N. M. 84433 3 .. ...do 7,000 ft.), 12 miles northwest of Fair- view, Sierra Co., N. Mex. Tucson, Ariz Nov. 7,1872 C. E. Ben- 304 205 30 19.5 53 L.B. Bishop 16877 s ...do Santa Catalina Mts., July 7,1906 dire. H. Kimball. 320 200 33 23 55.5 U.S.N.M. 1852693. ...do Ariz. Mount Tancitaro, Feb. 27, 1903 E. W. Nel- 320 210 31 22.5 55 U.S.N.M. 81925 8.. ...do Michoacan, Mex.& Guanajuato, Guana- son and E.A. Gold- man. A. Dugfe 302 196 30.2 20.8 53 U.S.N.M. 241187... juato, Mex. Blue, Ariz May —,1914 B.V. Lilly.. 321 212 31.5 22 54.5 1 Seven specimens, from Arizona and New Mexico. 2 Eight specimens, from Arizona, New Mexico, Michoacan, and Guanajuato. 8 Used in measurement averages on p. 257. 4 Type of Strix occidentalis huachucae Swarth. s Type of Syrnium Occident ale lucidum Nelson. 81022°— Proc. N. M. vol. 49—15 17