264 FRANCIS H. HERRICK 



US see how the immediate environment has apparently affected 

 the work of the builders in each case. The first is typical of 

 this bird, and was built in a fir tree at a height of five feet from 

 the ground. It is rather bulky, though smaller than a robin's, 

 standing 3^ inches, when removed from its support. The cup 

 is well modelled, and measures 2 inches deep by 2^ inches across 

 at the brim. Though the walls reach a thickness of two inches, 

 being rather loosely compacted of vegetable matter* only, the 

 whole is very light, weighing barely an ounce. Fine fir twigs, 

 rather fine dry grasses and rootlets, interspersed with Poly- 

 trichum and other mosses constitute most of the building mater- 

 ials, the cup being lined with the skeletonized leaves of a wild 

 cherry and a jet black vegetable fiber suggesting horse hair, 

 and probably representing setae of one of the mosses. 



The other nest, though thinner in construction weighs more, 

 and appears to have an earthen cup, fairly well modelled and 

 compacted, like a robin's. It was found in a peaty meadow, 

 and was taken when the young left it on July 12, so that its 

 lining has been more or less pulverized through use. The sug- 

 gestion that this bird has adopted the robin's peculiar methods, 

 however, is quickly dissipated, when we examine it more closely, 

 remember the environment, and the probable habit of using 

 moss in this species as the robin pulls stubble, and the amount 

 of damp earth liable under certain conditions to be taken to 

 the nest in consequence. The cup of this thrush's nest is not 

 strictly a " mud cup " at all, but appears to be formed of the 

 stalks and rhizoids of mosses pulled by the bird from the peaty 

 swamp, and of the black earth and sand thus casually obtained ; 

 this was later subjected to the molding movements of the bird 

 in the usual manner, and was further compacted by the weather 

 and the activities of the nestlings. Though such a nest presents 

 a very unusual appearance, if this interpretation is correct, it 

 is normal in every respect. 



Miss Stanwood, who has examined over thirty nests of the 

 Swainson or olive backed thrush, writes that they all have the 

 bulk and general appearance of the robin's, and are conspic- 

 uously placed in bushes or low trees. As many as thirty kinds 

 of vegetable materials sometimes enter into their loose outer 

 wall, while a thick inner layer of dead wood, which seems to 

 correspond to the mud cup of the robin is usually present and 



