BICKNELL'S THRUSH 203 



then placed a lining of fine black rootlets, to which may or may not 

 be added some dry, well-bleached grasses, and a leaf or two, the latter 

 often dumped carelessly into the finished nest, and then left for a day 

 or two, as if to mask the newness of the structure. 



The dimensions of 20 nests were as follows: Outside diameter, 

 4.00 to 5.50, averaging 4.50 by 5.00 inches; inside diameter, 2.25 to 

 3.40, averaging 2.47 by 2.79 inches; outside depth, 2.75 to 3.75, 

 averaging 3.34 inches; and inside depth, 1.50 to 2.50, averaging 1.81 

 inches. 



The projection of twigs beyond the body of the nest was not in- 

 cluded in the measurements of the outside diameter. Six nests had 

 the interior cavity perfectly symmetrical, but the remaining 14 showed 

 some distortion of diameter, usually due to compression of the nest 

 against the trunk of a tree. 



Nests are typically situated in small or medium-sized evergreens, 

 usually placed where two or more horizontal branches join the main 

 stem. Often it is set close against the trunk, so that the impression 

 of the tree is permanently registered in the wall of the nest; less 

 frequently it is a few inches to a few feet away from the trunk; and 

 in three instances (out of more that 30) nests were found at the 

 extremity of long low branches in large evergreen trees. 



Though all the nesting records in the literature refer to nests in 

 evergreens, three of the 30 or more structures located in the Mansfield 

 region were situated in birches. The birds' apparent preference for 

 evergreens is probably not alone due to the dominance of conifers 

 over deciduous growth, but is no doubt correlated with the fact that 

 birches (the only deciduous trees that are common at this altitude) 

 are not leaved out early in June when nest-building begins, and thus 

 would afford adequate concealment only for belated nests. 



In height above the ground the nests varied from 3 to 12 feet. The 

 average of 16 nests was 7.3 feet. Nests in the deep woods are 

 commonly higher than those out in the dwarfed groves near the 

 summit, the former being 8 to 12 feet high, the latter more often 5 or 

 6 feet. Tufts (Thayer, 1907) reported a Seal Island (Nova Scotia) 

 nests 25 feet high and two others at 15 feet. Bent (MS.), however, 

 found Seal Island nests at 8 to 10 feet, which closely corresponds to the 

 heights for Mount Mansfield nests in the deep woods. 



With few exceptions the nests are concealed in well-protected 

 situations, usually in or on the margin of a dense evergreen tangle, 

 so that the camouflaging character of the green mossy nests, and the 

 fact that the wary birds seldom offer give-away clues to its location, 

 make nest-hunting a painstaking and often unrewarding procedure. 

 The finished nest, in most cases, is an exceedingly artistic and sub- 

 stantial structure. Though a few nests fall in ruins at the close of 



