OUK CHIMNEY DWELLERS 21 



wall on the inside of some chimney. These twigs are the 

 ends of small, dead branches broken from the trees by the 

 birds, who grasp them with their feet or bill while on the 

 wing. They are fastened together by a salivary substance 

 secreted by glands in the bird's mouth. 



Sometimes the flow of this gluing secretion is checked. 

 This is possibly due in part to an unhealthy condition of 

 the bird. At such times the nest building must proceed 

 but slowly, and it may even be delayed until time for the 

 eggs to be deposited. Often nests have been examined 

 which contained eggs many days before the full number 

 of twigs had been glued in place. 



Before the settlement of this country the swifts built 

 their nests on the inner vertical sides of hollow trees, but 

 when the white man came with his chimneys they left their 

 homes in the forest and came to dwell with him. 



A chimney is usually occupied by but one pair of birds. 

 It is only in the autumn, when the swifts accumulate from 

 far and near about some favorite roosting place, that we 

 see so many inhabiting one chimney. Their eggs are four 

 or five in number, and are white. Nature is not inclined 

 to lavish her coloring material on the shells of eggs where 

 it is not needed. With few exceptions those which are 

 deposited in dark places, as in chimneys, or holes in trees, 

 or in the ground, are white. Such eggs do not need the 



