132 THE MIGRATIONS OF BIRDS 



In England and elsewhere in Europe shelves and 

 perches in some cases have been placed below the 

 lights, to afford resting places for birds, on which 

 they can remain until they have overcome their be- 

 wilderment. These have been of great service in the 

 conservation of life, and at a number of points where 

 birds in former years were killed by thousands now 

 few dead are found. Many modern lighthouses have 

 lights of an intermittent type, arranged to flash at 

 regular intervals, and often alternate colored rays 

 with the usual beams of white light. These intermit- 

 tent flashes, particularly where they are not white, 

 are not so attractive, so that at many lights the 

 danger has been largely eliminated. 



It would appear, too, that birds may learn to 

 avoid such dangers. The Washington Monument, a 

 square pillar rising to a height of 555 feet, was noted 

 for years for the destruction that it caused to small 

 migrants, particularly in autumn, and thirty or 

 forty years ago it was not unusual to find seventy- 

 five or one hundred dead warblers, sparrows, and 

 other small species about its base following a rainy 

 or foggy night. Since 1910 this destruction has prac- 

 tically ceased, and it is now unusual for even a few 

 birds to strike under the conditions mentioned. I 

 have watched this monument in recent years during 

 the time of migration, and have made many visits to 

 it to look for birds, but have seen very few. 



