10 



OLIVE-BACKED THRUSH, Turdus ustulatus swainsonii 



(Cab.) 



'In number of individuals, in the frequency of its melody, 

 and in its adaptation to the sombre surroundings of the lake 

 region, the olive-backed thrush is the typical breeding species 

 of the lake shore. Belonging to a more northern habitat, it 

 has been attracted by the evident conveniences of our Mon- 

 tana summer resort, and great numbers of representatives of 

 the species rear their families in the firs and other trees of the 

 Station neighborhood. Unlike most of the recorded breeding 

 species, however, it was only entering the period of nidifica- 

 tion at the time of these observations, the nests found during 

 the first few days being either recently completed and not yet 

 occupied, or having only the beginning of the regular comple- 

 ments. 



The opening of the nesting season for this species seems to 

 be quite uniform in the Flathead region, for nests examined the 

 same day showed remarkably equal progress in development 

 with others. Most of the nests found on June 14 and 15 con- 

 tained either one or two eggs, or else gave evidence of having 

 been just completed and not yet regularly occupied. It was 

 not until June 17 that a nest was examined containing a full 

 complement. 



The olive-backed thrush is one of the low builders. Of 

 twenty nests, none was over ten feet from the ground; two of 

 the twenty were placed at the foregoing limit, two were nine 

 feet from the ground, three at eight feet, three at seven feet, 

 four at about six feet, and the remainder three and one-fourth 

 feet and six feet from the ground. The average site is a trifle 

 over six and one-half feet from the ground. Distances were 

 carefully measured with a two-foot rule. 



The favored site of nests in fir trees was against the main 

 stem, at the base of one or more horizontal branches, and at a 

 point about three-fourths the height of the tree. In one in- 

 stance the nest was placed on a horizontal branch of a fir 

 tree about two feet from the main stem, at a place probably 

 measuring two-thirds the length of the branch from the trunk. 

 The nest nearest the ground was found in a triple crotch of 

 willow growing upright in a slender sprout. Another nest 

 was found made in an upright crotch of an oblique portion of a 

 dead, bent sapling bare of leaves. A syringa bush growing 

 beside a path where anglers were frequently passing was chosen 

 in one instance, and the nest placed in an upright crotch among 



