II B RARY OF THE UN IVERSITY OF ILLINOIS FI Return this book on OR^efore the Latest Date stamped below. A charge is made on all overdue books. University of Illinois Library I M32 ZOOLOGICAL SERIES OF FIELD MUSEUM OF NATURAL HISTORY Volume XX CHICAGO, DECEMBER 31, 1938 No. 37 A NEW WOOD OWL FROM CHILE BY LESLIE WHEELER' LATE RESEARCH ASSOCIATE, DIVISION OF BIRDS The acquisition recently by Field Museum of several owls from Chile and Paraguay, allied to Strix rufipes, has enabled me to revise this group with more material for direct comparison than has been assembled heretofore. Eight specimens including the type of chacoensis have courteously been loaned by the American Museum of Natural History, the Museum of Comparative Zoology, the United States National Museum, the University of Michigan and the Philadelphia Academy of Natural Sciences. Strix rufipes sanborni subsp. nov. Type from Quellon, Chiloe Island, Chile. No. 62271 Field Museum of Natural History. Adult male. Collected December 23, 1922, by Colin C. Sanborn. Orig. No. 14. Diagnosis. — Smaller and darker than S. r. rufipes; barring of the upper parts almost absent, and on the remiges and rectrices very indistinct; white throat and superciliary line of rufipes replaced by grayish brown, heavily mottled with darker. Smaller and darker than S. r. chacoensis; dark and light markings blended and not so sharply contrasted. Description.— Crown chocolate brown; superciliary buffy gray heavily mottled with chocolate; nasal and frontal plumes black with slight indication of grayish buff at their bases; facial disk dark brown; a black spot in front of the eye; below and behind the eye an area of dark reddish brown heavily mottled with umber; rim of facial disk blackish chocolate with faint mottling of buffy. Throat and upper breast smoky brown mottled with darker brown. Feathers of 1 Before his death in 1937, Leslie Wheeler had assembled the material for this study and tentatively reached the conclusions here presented. References to the literature, additional measurements and remarks have been added to his manu- script by Rudyerd Boulton, Curator of Birds, as well as conclusions drawn from consideration of remarks by Messrs. N. B. Kinnear and J. Berlioz, who have cour- teously compared the unique specimen with the types of rufipes and fasciata in the British Museum and the Paris Museum respectively. No. 433 479 480 FIELD MUSEUM OF NATURAL HISTORY — ZOOLOGY, VOL. XX breast, belly and flanks chocolate brown crossed by four lighter bars, the subterminal bar being white and the three basal bars buff. Upper parts chocolate brown, with sparse, irregular and indistinct buffy bars, most numerous on the upper back and scapulars and upper tail coverts; feathers of the lower back without bars. Wings chocolate brown; lesser coverts, primary coverts and alula without bars; middle and greater coverts irregularly barred with buffy; primaries and secondaries with discontinuous bars or "notches" of buff that do not touch the shafts of the feathers. Under wing coverts buff, heavily marked with chocolate. Under tail coverts buff with in- distinct brown bands and a white subterminal band. Tail chocolate brown crossed by about eight narrow, indistinct and discontinuous buffy gray bars. Legs and toes rich ochraceous orange. Measurements. — Dimensions of the three races are as follows: S. r. sanborni, I male (type): wing, 241; tail, 141; tarsus, 44; culmen from base, 25; culmen from cere, 16.5. S. r. rufipes, 3 males, 4 females: wing, males 250-264 (255.6), females 261-275 (268.2); tail, males 151-156 (152.7), females 156-161 (158.5); tarsus, males 47-51 (48.7), females 47-50 (48.0); culmen from base, males 28-29 (28.3), females 29-30 (29.2); culmen from cere, males 18-19.5 (18.8), females 19-21 (20.0). S. r. chacoensis, 2 males (including the type), 2 females: wing, males 251-263 (257.0), females 281-291 (286.0); tail, males 146-150 (148.0), females 162-163 (162.5); tarsus, males 50-51 (50.5), females 50-53 (51.5); culmen from base, males 32-33 (32.5), females 32-33 (32.5); culmen from cere, males 20 (20.0), females 20-22 (21.0). Remarks. — Although the total series of fifteen specimens for direct comparison is small, certain definite conclusions can be drawn. The unique type is immediately distinguishable from all other speci- mens examined by any one of a number of characters as shown below. When our first specimen of chacoensis was received I was inclined to agree with Cherrie and Reichenberger1 that this form was not con- specific with rufipes. The whole series, however, shows that it is clearly the "geographical representative" of rufipes and all characters that it possesses are the result of the accentuation of tendencies found in rufipes. Hellmayr2 appears to be the first to have regarded it as a race of rufipes. 1 Amer. Mus. Novitates, No. 27, p. 2, 1921. * Field Mus. Nat. Hist., Zool. Ser., 19, p. 271, 1932. 1938 A NEW WOOD OWL FROM CHILE— WHEELER 481 The new form sanborni on the other hand shows opposite ten- dencies to as great a degree. The type specimen was referred by Hellmayr1 to typical rufipes without comment. Field Museum did not at that time possess adult specimens of typical rufipes, so direct comparison was not possible. Strix rufipes was described by King- from Port Famine, Straits of Magellan, from one specimen. The type is in the British Museum. The color as stated in the original description agrees well with that of seven adult specimens before me. The measurements of the type slightly exceed those of any of the seven which come from localities somewhat farther north. Unfortunately, no topo typical material of rufipes has been available for comparison with our series. Mr. Kinnear has kindly compared the type of sanborni with the type of rufipes and says in part: "Your bird differs from the type of rufipes in the much darker colour above, not so brown, the barring not so distinct, and in the darker colour of the neck and breast. A young bird from Temuco is similar above and below to the three adults from the same place." M. Berlioz has courteously compared for me the type of sanborni with the type offasciata Des Murs3 (nee Vieillot). The namefasciata Des Murs is not available for this species under any circumstances as Mr. J. L. Peters has kindly informed me, since it is antedated by Strix fasciata Vieillot4 from "Martinique." M. Berlioz says in part: "The type of fasciata (wing 264 mm.) agrees in size with your speci- men from Lautaro, Chile, and is larger than the bird from Chiloe. It is much more variegated than the latter and the upperside and the barring of the tail resemble the Lautaro specimen. On the under- side the bars are more regular and more numerous than in the Lautaro bird and show an approach to the specimen from Chiloe although the general colour is lighter and the white bars on the chest and breast are wider." It has been suggested that the type of sanborni is not adult. Juvenal specimens of both rufipes and chacoensis have been directly compared with the type and they show no resemblance. The salient features of the three races of rufipes are summarized in the table on page 482. 1 Loc. cit., p. 270. 1 Zool. Journ., 3, p. 426, 1826. 3 Icon. Ornith., livr. 7, pi. 37, 1847. * Nouv. Diet. Hist. Nat., 7, p. 31, 1817. 482 FIELD MUSEUM OF NATURAL His TORY— ZOOLOGY, VOL. XX sanborni rufipes chacoe nsis smallest intermediate largest dark and blended intermediate light and contrasting indistinctly irregularly strongly mottled barred barred indistinct buff distinct buff white discontinuous continuous and continuous and narrow broad black and buff brown and white black and white gray brown light gray pure white discontinuous continuous and continuous and narrow broad unbarred unbarred barred Size General tone Back Mottling of upper parts . Barring of tail Rim of facial disk Upper chest Barring of primaries .... Primary coverts The following specimens have been examined: Strix rufipes rufipes. — 9: CHILE (Mafil, Valdivia; Maquehue, Cautin; Curacautin, Malleco). ARGENTINA (Rio Chico Cordilleras, Santa Cruz). Strix rufipes sanborni. — 1 (type): CHILE (Quellon, Chiloe Island). Strix rufipes chacoensis. — 5 (including type) : PARAGUAY (Fort Wheeler, Chaco; 265 kilometers west of Puerto Casado).