240 



birds might build the characteristc nests of wild 

 Grosbeaks. I also placed in the cage rootlets, straw, 

 small sticks and twigs, in short, as nearl}^ as I could, 

 the same material that I found in the nests of wild 

 Rose-breasted Grosbeaks. These the birds eagerly 

 availed themselves of and for ten days or more 

 engaged themselves most busily in abortive attempts 

 at nest-building. The}' seemed unable to arrange a 

 suitable foundation of rootlets and twigs in any of the 

 crotches and branches I had given them, and after 

 this had gone on for two weeks and no progress 

 had been made, I determined to give them artificial 

 nests. These were the kind of nests supplied to 

 Canary' birds, being wire baskets of fine mesh into 

 which a felting of cowhair is securely sewed. 



In both cases the Grosbeaks availed themselves 

 of these nests at once and proceeded to utilize 

 feathers and some extra cowhair that I had given 

 them to complete the lining of the structure. In four 

 days after receiving these nests both females had 

 begun to lay; but, though each female laid a full 

 complement of eggs, these were generalh' broken b}'' 

 the birds. The first three or four eggs laid had hard 

 shells, and after that each of the females laid several 

 eggs with soft shells. The way I account for the eggs 

 being broken is that both birds of each pair, after an 

 egg had been laid in the nest, continued their eiforts 

 to build a structure more to their liking, and it was 

 their claws as they trampled about that 2:)erforated the 

 shell of the eggs already laid. 



After the first laying which I have described as 

 abortive, an interval of perhaps a week intervened, 

 when laying began again with almost precisely the 

 same results. All this time the males were constantly 

 singing, courting the females, feeding them, caressing 

 them, and the operation of treading was frequentl}'' 

 witnessed throu<zliout the dav. 



