82 AMERICAN ORNITHOLOGY. 



of suitable size will answer. Both birds assist in the labor and they do a 

 great deal of talking as they work. As in the case of most woodpeckers, the 

 chips are carried to some distance before they are dropped, and only rarely 

 is a nest found where there will be any evidence of work on the ground at the 

 foot of the tree. Their four or five eggs are pure white, and glossy; they 

 measure 1.00 x .7;) inches. P'or perhaps a day after thej^ are hatched, the 

 young are fed upon regurgitated food, but after that they are fed upon solid 

 food which the parents bring to them in their bills. If the trunk of the tree 

 containing a nest and young, is struck a sharp blow, they will often com- 

 mence a loud buzzing sound like a great hive of bees. This sound is also 

 produced by the majority of other sj^ecies. 



THE MIGRATION OF BIRDS, 

 By Carl L. Kapp. 



With the advent of spring, those who are interested in ornithology, watch 

 with eager interest for the advance guard of the vast host of migrating birds. 

 March, though a period of unsettled weather, is, properly speaking, the 

 month when the spring migration begins. But an unusually mild spell dur- 

 ing the latter part of February, may possibly induce the Bluebird and Song 

 Sparrow, two species numbered among our permanent residents (in Iowa), 

 to prematurely welcome spring and inaugurate the season of song. Soon 

 after this, if the conditions of the weather remain favorable, we may expect 

 the appearance of the Robin, Purple Grackle and others. Another unde- 

 niable evidence of the approach of spring is seen in the preparations of the 

 Great Horned Owl, another permanent resident, for the construction of a 

 nest early in March. 



As the season advances, and one sees the passing of countless feathered 

 hosts, the summer residents dropping from their ranks as their summer home 

 is reached; the transient visitants pausing for a time only and then contin- 

 uing their journey, the old vexed question as to the cause of this bi-annual 

 movement of the feathered tribes presents itself. So many are the difficul- 

 ties and objections which present themselves, that a clear and concise so- 

 lution of the problem seems impossible. I have discussed the question with 

 many people who were well versed in bird study, as well as with many who 

 take but little interest in the birds. So many were the theories advanced that, 

 to present them all here, would be out of the question. But the most plausi- 

 ble in the minds of many is that of food supply. 



Converse with some of the supporters of this theory and they will draw 

 your attention to the fact that when the ice leaves the rivers and lakes, we 



