230 FRIENDS WORTH KNOWING. 



sometimes, in defect of hair, lining the interior with a mixt- 

 ure of slender strips of smooth vine bark, and rarely with 

 a few feathers; the whole being of a considerable thick- 

 ness and more or less attached to the external pouch. Over 

 the top the leaves, as they grow out, form a verdant and 

 agreeable canopy, defending the young from the sun and 

 rain. There is sometimes a considerable difference in the 

 manufacture of these nests, as well as in the materials 

 which enter into their composition. Both sexes seem to 

 be equally adepts at this sort of labor ; and I have seen the 

 female alone perform the whole without any assistance, 

 and the male also complete this laborious task nearly with- 

 out the aid of his consort, who, however, in general, is the 

 principal worker." 



Many persons believe that there is a constant tendency 

 in birds to vary their architecture to suit their surround- 

 ings, in accordance with climate, greater or less readiness of 

 certain materials, and security. The Baltimore oriole af- 

 fords a good illustration of this tendency. Like the swal- 

 lows, robin, bluebird, pewit, and others, the oriole has aban- 

 doned the wilds for the proximity to man's settlements, do- 

 ing it chiefly for two reasons the greater abundance of 

 insect food, and protection from hawks, owls, and crows, 

 which are fewer in number and less bold in the clearings. 



