. American Bird Magazine, Ornithology . uction von Anest Anfang März. Wenn die Saison fortschreitet, und man sieht das Vergehen von zahllosen Featheredhosts, die Sommer Bewohner fallen aus ihren Reihen, wie ihre Sommer homeis erreicht; Die vergänglichen Besucher, die nur eine Zeit innehalten und dann ihren Weg zurücklegen, stellt sich die alte ärgerliche Frage nach der Ursache dieser Zweijährigen Bewegung der gefiederten Stämme. So viele sind die difficulties und Einwände, die sich präsentieren, dass eine klare und prägnante Lösung des Problems unmöglich scheint. Ich habe die Frage mit vielen peo diskutiert
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. American bird magazine, ornithology . uction of anest early in March. As the season advances, and one sees the passing of countless featheredhosts, the summer residents dropping from their ranks as their summer homeis 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-annualmovement 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 withmany people who were well versed in bird study, as well as with many whotake 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 drawyour attention to the fact that when the ice leaves the rivers and lakes, we AMERICAN ORNITHOLOGY. 83. Photo from life by A. D. Wheedon.Catbird With Food for Her Young. 84 AMERICAN ORNITHOLOGY. notice that the geese and ducks put in an ajjpearance, but not before. Alsoat this time we may expect the so-called enemy of the fisherman, the BeltedKingfisher. With the advent of the insect season, we note the arrival ofthose species which are wholly insectivorous. Again, in the fall, when thetemperature becomes such that the ground is hardened and the ice forms onthe 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 edgesof ponds and lakes, also leaAe as soon as the ground hardens. Now, while all these facts, for facts they are, together with many otherswhich are presented by the supporters of the food-supply theory, are unde-niably true, there are manv objections to be answered before it will be gen-erally accepted as the one and only cause for migration. For
