THE OLIVE-BACKED THRUSH. 235 



nnined places, nests might be set against tlie trunk on a horizontal limb, but 

 were more often at some distance from it. The birds were very sensitive 

 about molestation before eggs were laid, and would desert a nest in process 

 of construction on the merest suspicion that a stranger had looked inti) it. 

 After deposition, however, the mother Thrush was fountl to be very devoted 

 to her charges, and great confidence was often engendered by carefully con- 

 sidered advances. 



At Glacier, nest-building averaged to commence about the 25th of May, 

 and the first eggs were found on the ist of June. The last set was found July 

 15th. All nests examined in the earlier part of the season contained four 

 eggs: those found later, presumably second efforts, never had more than three. 



As a curious example of the use of the imagination on the part of early 

 writers, take this from our \'enerated Cooper^: "The eggs, unlike those of 

 most thrushes, are white, spotted thickly with brown, and four or fi\'e in 

 number." The brown spotting is all right and an unpigmented shell is not an 

 impossibilit}-, Ijut deviations from the characteristic greenish blue of the 

 ground-color ha\'e not since been reported. 



No. 94. 



OLIVE-BACKED THRUSH. 



A. O. U. No. 758a. Hylocichia ustulata swainsonii (Cab.). 



Synonyms. — Sw.mnson's Thrush. Eastern (Jlixk-eack. Alma's 

 Thrush {H. 11. alma Oberh., disallowed by A. O. U. Com. ). 



Description. — Adults: Similar to //. ustulata but grayer and more olivace- 

 ous ; "color of upperparts varying from olive to grayish hair brown in summer, 

 from deep olive to slightly browni.sh olive in winter" : ground color of underparts 

 lighter buffy (yellowish buff or creamy buff) ; sides and flanks grayish — instead 

 of brownish-olive. Size of last. 



Recognition Marks. — As in preceding ; grayer above, lighter buft'y below. 



Nesting. — Nest and Eggs indistinguishable from those of typical form, H. 

 ustulata. 



General Range. — North America in general except Pacific coast district 

 south of Cross Sound and Lynn Canal: breeding from the mountainous districts 

 of the United States (especially northerly) north to limit of trees: south in winter 

 thruont Mexico and Central America to Peru, Bolivia, etc. 



Range in Washington. — Imperfectly made out as regards that of H. 

 ustulata. Found breeding in the valley of the Stehekin hence presumably summer 

 resident in timbered districts of eastern Washington. 



Authorities. — Bowles and Dawson, Auk. \'ol. XXV. Oct. 1908, p. 483. 



Specimens. — Prov. B. 



Rep. Pac. R. R. Siirv., \'oI. XII., Book II., iS6o, p. 171. 



