BIRDS AND LIGHTHOUSES 277 



The height at which birds travel is believed to 

 depend more on the state of the weather at starting 

 than on the direction of the wind. On clear light 

 nights, as a rule, they travel high. In fog, rain, or 

 snow, and in thick, murky weather they fly low, 

 often only a few feet above the waves. On dark 

 nights lost birds will wheel for hours round a light- 

 ship, but with the first break in the clouds, the 

 stars appearing, or streak of early dawn, they are 

 on their course again to the nearest land. The 

 comparatively low altitude at which they travel 

 during foggy or dull weather has probably a good 

 deal to do with the numbers which are killed at 

 lighthouses. Broadly speaking, it is the brightest, 

 whitest, fixed lights which best penetrate the fog 

 or darkness, and attract most birds. 



These are some of the more interesting facts 

 which have been brought to light through the 

 agency of the lighthouse-keepers, and we are now 

 in a fair way, through their instrumentality, of 

 obtaining a satisfactory solution to some of the 

 vexed questions upon the subject of migration 

 which I have attempted briefly — I fear somewhat 

 imperfectly — to explain.^ 



1 This chapter formed the substance of one of the " Davis 

 Lectures " which I gave under the auspices of the Zoological 

 Society at the Regents Park Gardens. 



