24 NORTH AMERICAN BIRDS. 



the ]\Iackenzie Eiver and the Coppermine, more than 200 specimens 

 (mostly with their eggs) having been sent thence to the Smithsonian 

 Institution by Mr. MacFarlane. In all this number there was not a 

 single bird thai: had any approach to the characters of T. swainsoni, as 

 just given. Trom the Slave Lake region, on the other hand, T. swainsoni 

 was received in nearly the same abundance, and unmixed during the 

 breedino- season with T. alicicc. 



Turdus swainsoni, Cabaxis. 



OLIVE-BACKED THRUSH; SWAINSON'S THRUSH. 



Turdus sioainsoni. Cab. Tschudi, Fauna Peruana, 1844-46, ISS. — ?Sclater & Salvix, 

 Ibis, 1859, 6 (Guatemala). —Sclater, P. Z. S. 1858, 451 (Ecuador); 1859, 326.— 

 Ib. Catal. 1861, 2, no. 11. — Baird, Birds X. Am. 1858, 216; Rev. Am. B., 1864, 19. 

 — GuNDLACH, Cab. Jour. 1861, 324 (Cuba). — Ib. Repert. 1865, 229. — Pelzeln, Orn. 

 Brazil, ii. 1868, 92 (Marambitanas, Feb. and March). — Lawr. N. Y. Lye. IX, 91 

 (Costa Rica). — Ridgway. — Matnard. — Saaiuels, 152. — Cooper, Birds Cal. 6. — 

 Dall & Bannister. Turdus minor, Gmelin, Sy.st. Kat. I, 1788, 809 (in part). 

 Turdus olivaceus, Girauu, Birds L. Island, 1843-44, 92 (not of Linn.). (/) Turdus 

 minimus, Lafresnaye, Rev. Zool. 1848, 5. — Sclater, P. Z. S. 1854, 111. — Bryant, 

 Pr. Bost. Soc. VII, 1860, 226 (Bogota). — Lawrence, Ann. X. Y. Lye. 1863. (Birds 

 Panama, lY, no. 384.) 



Sp. Char. L'pper parts uniform olivaceous, with a decided shade of green. The fore 

 part of breast, the throat and chin, pale brownish-yellow ; rest of lower parts white ; 

 the sides washed with brownish-olive. Sides of the throat and fore part of the breast 

 with sub-rounded spots of well-defined brown, darker than the back ; the rest of the 

 breast (except medially) with rather less distinct spots that are more olivaceous. Tibise 

 yellowish-brown. Broad ring round the eye, loral region, and a general tinge on the 

 side of the head, clear reddish buff. Length, 7.00 ; wing, 4.15 ; tail, 3.10 ; tarsus, 1.10. 



Hab. Eastern Xorth America ; westward to Humboldt Mountain and Upper Columbia; 

 perhaps occasionally straggling as far as California ; north to Slave Lake and Fort Yukon ; 

 south to Ecuador and Brazil. Cuba, GtUNDLACH ; Costa Rica, Lawr. 



Specimens examined from the northern regions (Great Slave Lake, Mac- 

 kenzie Eiver, and Yukon) to Guatemala ; from Atlantic States to East 

 Humboldt ^Mountains, Xevada, and from intervening localities. The ex- 

 tremes of variation are the hrow7iish-o\i\e of eastern and the clear dark 

 greenish-olive of remote w^estern specimens. There is no observable dif- 

 ference between a Guatemalan skin and one from Fort Bridger, Utah. 



Habits. The Olive-backed Thrush, or " Swamp Eobin," has very nearly 

 the same habitat during the breeding season as tliat of tlie kindred species 

 with which it was so long confounded. Although Wilson seems to have 

 found the nest and eu'o-s amono- the hioh lands of Xorthern Georoia, it is yet 

 a somewdiat more northern species. It does not breed so far south as 

 ]Massachusetts, or if so, the cases must be exceptional and very rare, nor 

 even in Western Maine, where the "Ground Swamp Eobin" (T. pallasi) is 

 quite abundant. It only becomes common in the neighborhood of Calais. 



