350 THE POPULAR SCIENCE MONTHLY. 



all of them, congregating in the adjoining fields and in the trees of the 

 gully, and quite suddenly they would all disappear. Searching every 

 possible hiding-place, I finally found them as above described. If 

 the following day proved very cold or stormy, many of them would 

 remain in their snug retreat, the arctic visitors being the first to 

 venture out. The birds just mentioned all build open nests, either 

 in trees or upon the ground. On the other hand, the titmouse, nut- 

 hatch, brown tree-creeper, and bluebird, all of which build nests in 

 hollow trees, or sheltered spots of that character, I found regularly 

 roosted in the hollow trees, or in the outbuildings of the farm. The 

 cardinal redbirds, however, which nest in trees and brier-patches, 

 usually took refuge in dense cedars, to roost, but sought other shelter 

 during severe storms. For instance, during the remarkable wind- 

 storm of February 9th, when the air was filled with dust, and the 

 thermometer ranged from 3 to 4^ Fahr., no ordinary shelter could 

 protect our resident birds. During the day not one was to be seen 

 flying. I found the cardinal redbirds a pair of them had taken 

 shelter in a large, hollow tree, and with them was quite a large num- 

 ber of titmice,- a brown tree-creeper (Certhia familiaris), and several 

 sparrows. I do not doubt but that the earth-shelter already described 

 had proved inadequate, and that the birds usually roosting there had 

 sought more sheltered spots. However, I did not have the courage to 

 face the wind, and see for myself, if such was the case. 



During the present winter I have found that some, at least, of our 

 winter birds utilize the very excellent shelter afforded by the nests of 

 our bank-swallows. February 20th, a bright, clear day, I passed by 

 a high, steep cliff of compact sand and clay, much frequented by these 

 swallows during summer. I noticed there chipping-sparrows and a 

 bluebird sunning themselves, each at the opening of a nest. On driv- 

 ing them away I found that they circled about for a few moments, and 

 retmmed. On passing the cliff again, some hours later, I saw these 

 birds, and several others, some at the openings of the nests, and 

 others flitting about, quite in the manner of swallows. I could not 

 reach the nests, to determine if they had been much occupied during 

 the winter, but do not doubt but that such was the case. 



I have not found, however, any shelters constructed by birds for 

 such purpose solely, except in the case of the introduced English 

 sparrow, which builds quite an elaborate and very warm roosting- 

 nest. During the early frosts of autumn and prevalence of cold rain- 

 storms, occurring before the ordinary date of migratorial departure, 

 the nests used in spring and summer are, I know, used as roosting- 

 places, but I have not detected any refitting of them for this purpose. 

 Considering this, it would be natural for birds to build new structures 

 for winter use, and in the sparrow we have an instance of it, and, I 

 presume, the abundance of natural shelter has alone prevented the 

 gradual acquirement of this habit by our winter birds. 



