84 AMERICAN ORNITHOLOGY. 



notice that the geese and ducks put in an appearance, but not before. Also 

 at this time we may expect the so-called enemy of the fisherman, the Belted 

 Kingfisher. With the advent of the insect season, we note the arrival of 

 those species which are wholly insectivorous. Again, in the fall, when the 

 temperature becomes such that the ground is hardened and the ice forms on 

 the water, we find that all the species that derive their food from the water, 

 leave, and those whose nature it is to probe in the soft mud about the edges 

 of ponds and lakes, also leave as soon as the ground hardens. 



Now, while all these facts, for facts they are, together with many others 

 which are presented by the supporters of the food-supply theory, are unde- 

 niably true, there are many objections to be answered before it will be gen- 

 erally accepted as the one and only cause for migration. For instance, if the 

 food supply governs the migrations of birds, why is it that members of those 

 species included in the list of permanent residents, that is, those species 

 that are represented in northern localities all the year round, remain and 

 vary their diet according to the season ? Why do not other species learn to vary 

 their diet and thus escape periling their lives in the long journeys to and fro? 

 We see, many times during hard winters, flocks of English Sparrows clus- 

 tering miserably together, and starving for want of food. Why does not 

 this hardy little bird learn the lesson of migration as other species have 

 learned it? Again, why is it that birds that pass the winter in tropical re- 

 gions leave at the time when the tropical season is at its height, and the insect 

 life is at its best, to come northward to a land where the last traces of winter 

 have hardly vanished? 



Mr. Frank M. Chapman, in "Bird-Life," makes this statement: — "I be- 

 lieve that the origin of this great pilgrimage of countless millions of birds is 

 to be found in the existence of an annual nesting season. In my opinion, it 

 is exactly paralleled by the migration of shad, salmon and other fishes to 

 their spawning grounds, and the regular return of seals to their breeding 

 rookeries. Most animals have a desire for seclusion during the period of 

 reproduction, and when this season approaches, will seek some retired part 

 of their haunts or range, in which to bring forth their young." 



A little further on in this discussion of the same subject, he says: — "There 

 is very good reason to believe the necessity of securing a home in which their 

 young could be reared was, and still is. the cause of migration. It must be 

 remembered, however, that birds have been migrating for ages, and that the 

 present conditions are the result of numerous and important climatic changes." 

 He also says that many species of tropical sea birds resort each year to some 

 rocky islet, where they may nest in safety. This is not migration in the 

 proper sense of the term, but the object is the same that prompts the plover 

 to travel to the Arctic regions, and the movement is just as regular. As in 



