BIRD MIGRATION. 29 



imperfect and frequently at fault. Doubtless a similar but vastly more 

 acute sense enables the murres, flying from home and circling wide 

 over the water, to keep in mind the direction of their nests and re1 urn 

 to them without the aid of sight. 



But even the birds' sense of direction is not infallible. Report s from 

 lighthouses in southern Florida show that birds leave Cuba on cloudy 

 nights, when they can not possibly see the Florida shores, and safely 

 reach their destination, provided no change occurs in the weather. 

 But at fickle equinoctial time many flocks starting out under 

 auspicious sides find themselves suddenly caught by a tempest. 

 Buffeted by the wind and their sense of direction lost, these buds fall 

 easy victims to the lure of the lighthouse. Many are killed by the 

 impact, but many more settle on the framework or foundation until 

 the storm ceases or the coming of daylight allows them to recover 

 their bearings. 



A favorite theory of many American ornithologists is that coast 

 lines, mountain chains, and especially the courses of the larger rivers 

 and their tributaries form well-marked highways along which birds 

 return to previous nesting sites. According to this theory, a bird 

 breeding in northern Indiana would in its fall migration pass down 

 the nearest little rivulet or creek to the Wabash River, thence to the 

 Ohio, and reaching the Mississippi would follow its course to the Gulf 

 of Mexico, and would use the same route reversed for the return trip 

 in the spring. The fact is that each county in the Central States con- 

 tains nesting birds which at the beginning of the f aU migration scatter 

 toward half the points of the compass; indeed, it would be safe to say 

 all the points of the compass, as some young herons preface their 

 regular journey south with a little pleasure trip to the unexplored 

 north. In fall most of the migrant land birds breeding in New 

 England move southwest in a line approximately parallel with the 

 Allegheny Mountains, but we can not argue from this that the route 

 is selected so that mountains will serve as a guide, because at this 

 very time thousands of birds reared in Indiana, Illinois, and to the 

 northwestward are crossing these mountains at right angles to visit 

 South Carolina and Georgia. This is shown specifically in the case 

 of the palm warblers. They winter in the Gulf States from Louisiana 

 eastward and throughout the Greater Antilles to Porto Rico; they 

 nest in Canada from the Mackenzie Valley to Newfoundland. To 

 migrate according to the "lay of the land," the Louisiana palm 

 warblers should follow up the broad open highway of the Mississippi 

 River to its source and go thence to their breeding grounds, while the 

 warblers of the Antilles should use the Allegheny Mountains as a 

 guide. As a matter of fact, the Louisiana birds nest in Labrador and 

 those from the Antilles cut diagonally across the United States to 

 summer in central Canada. These two routes of palm warblers 



