MIGRATION 173 



before visited. It was found that marked birds could 

 return to their nests after being transported in closed baskets 

 to Galveston in Texas, more than 800 miles away. Some 

 returned in about six days, some took nearly twelve, some 

 did not return at all. 



Two Noddies and two Sooties were taken in the state- 

 room of a steamer to Havana ; they returned next day to 

 Bird Key, a distance of 108 miles. Of five birds liberated 

 off Cape Hatteras at least three returned in a few days, 

 having accomplished a journey of 850 miles as the crow 

 flies, and of much more if the alongshore route was followed. 

 Four Noddies and four Sooties were taken in a hooded cage 

 on a Galveston steamer to about 461 statute miles from 

 Bird Key and liberated where no shore line was visible. 

 " On release all birds with one exception started east 

 (homewards). That one headed west and continued for 

 about 200 yards, then turned suddenly and started east." 

 They had a strong head wind against them throughout the 

 first day, but two of the Noddies returned in safety to 

 Bird Key. 



Dr. Lashley has shown that for short distances on the 

 island itself the terns adjust themselves to the nest, their 

 mate, and their young, on a basis largely of visual experience, 

 helped a little by memory of movements, and sometimes by 

 sounds. But the investigators are not prepared to offer 

 any solution of the problem of distant orientation. They 

 have proved that untrained birds can return successfully 

 across the apparently trackless sea from a distance of 800 

 to 1000 miles, but they do not know how it is done. The 

 possibility of utilising landmarks seems quite excluded ; 

 there is no evidence that the retina of the bird is specially 

 sensitive to infra-luminous rays ; there is no evidence that 

 birds nose their way through the air feeling the direction, 

 strength, and temperature of the wind as it plays on the 

 mucous membrane of the nasal cavity. It is possible that 

 there may be on other parts of the body tactile or thermal 

 nerve-endings which react to slight differences in pressure, 

 temperature, and humidity. There may be some sensitiveness 



