358 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



was that of the robin, both nests being well made and complete in every 

 detail." His photograph of it shows four eggs of the thrasher and one 

 of the robin. The thrasher was on the nest, which was afterward 

 destroyed by some unknown enemy. E. D. Nauman (1930b) found a 

 thrasher incubating on its nest, with two of its own eggs and two of 

 the cardinal under it. The cardinal's eggs were evidently deposited 

 about a week after incubation had begun on the thrasher's eggs, for 

 the next time he visited the nest it contained two young thrashers and 

 two eggs of the cardinal, on which the latter bird was incubating. 

 This nest also came to grief. 



Dr. Erwin (1935) gives a very full account of the building of the 

 nest, in which both birds take part, and a good description of the com- 

 position of the nest : 



The later nests were more poorly constructed than the earlier ones. Five to 

 seven days were usually required for the construction of the earlier nests, vphile 

 only three to four days vpere required for the later ones. It also seemed that 

 the type of location of the nest had something to do with the amount of materials 

 used. 



Twenty-three nests were carefully examined to discover the architecture and 

 materials of construction. The nests were composed of four concentric layers, 

 or baskets. The first basket was composed entirely of twigs, usually from four 

 to twelve inches long and from ^Ae to 14 of an inch in diameter. The second 

 basket was composed principally of dead leaves. A few pieces of paper, thin 

 bark, and tiny twigs were sometimes used. The third basket was composed of 

 tiny twigs and grass stems. In a few of the later nests this basket was almost 

 completely lacking. The fourth basket, or lining, was usually composed of well- 

 cleaned rootlets, mostly from grasses. In a few cases petioles of the Honey 

 Locust were used exclusively. 



He gives an account of the building operations in too great detail 

 to be quoted here. The birds had considerable difficulty in carrying 

 the twigs through the thickly entwined branches of the shrubbery; 

 often the twigs were left hanging where they were caught, and some- 

 times they were recovered but sometimes not. When the female ap- 

 parently discovered a desirable place, "with her bill she pushed the 

 twigs closer together, then got on the thickly matted stems and began 

 the movements in which many birds engage during nest building. 

 She intermittently lowered her head, relaxed her wings, and with 

 rapid jerks shifted her feet sidewise." This method of nest-shaping 

 was continued with each of the successive layers. At one nest he noted 

 that the female made 28 and the male 21 trips to the nest between 2 : 45 

 and 4 : 40 p. m. 



Soon after the young have left the first nest, the female starts build- 

 ing a second nest, leaving the male to care for the first brood of young. 

 At one nest the young left the nest on May 5, and on May 10 the female 

 was discovered putting the lining into the second nest. Another 

 female was seen completing a second nest 11 days after the young had 

 left the first nest. Mr. Saunders tells me that a pair that he watched 



