Jan., 1918 DESTRUCTION OF BIRDS AT LIGHTHOUSES, CALIFORNIA COAST 



The returns seem to indicate that the danger to birds increases in direct 

 proportion to the distance of the lighthouse lantern above the ground, while 

 the general elevation of the whole structure is also an important factor. Many 

 of the lighthouses are situated near sea level and at the foot of high bluffs, and 

 not one so situated reports any bird destruction. But where the lighthouse is 

 located on a height, even though it be not very high itself, there is considerable 



Fig. 2. Lighthouse at Point Arena, Mendocino County, Cali- 

 fornia. The "brick chimney" type, whose great height 

 makes it dangerous to birds. The light at this station is 

 155 feet above the sea, and the keeper reports from ten to 

 thirty birds per night killed on calm, dark nights during 

 the migration seasons. 



Courtesy of the Lighthouse Service, U. S. 

 Dept. Commerce. 



mortality. This is indicated by the fact that the average elevation of all the 

 lighthouses reporting birds killed is 165 feet, while the average elevation of all 

 the lighthouses reporting no birds killed is only eighty-eight feet. 



III. The larger birds are killed by flying violently against the glass or 

 other portions of the lighthouse structure ; small birds are also sometimes killed 

 in this way, but sometimes also they become confused, and fly about and 



