174 Twelve Months With 



doubled or trebled by these birds every day, by 

 reason of their darting, irregular flight in search 

 of food. Mr. Cooke calls attention to an interest- 

 ing fact which results from the wonderful migra- 

 tion habits of this bird : 



"The Arctic tern has more hours of daylight and 

 sunlight than any other animal on the globe. At the 

 most northern nesting site the midnight sun has already 

 appeared before the birds' arrival, and it never sets 

 during their entire stay at the breeding grounds. Dur- 

 ing two months of their sojourn in the Antarctic the 

 birds do not see a sunset, and for the rest of the time 

 the sun dips only a little way below the horizon, and 

 broad daylight is continuous. The birds therefore 

 have twenty-four hours of daylight for at least eight 

 months in the year, and during the other four months 

 have considerably more daylight than darkness."* 



Very few observations have been made as to the 

 migration route of this bird and its exact route is 

 unknown, but it has been recorded as an irregular 

 visitant along the Atlantic Coast. 



The only tern that is a common resident in the 

 Central States is the black tern. It is a summer 

 resident in this latitude, while the Caspian, com- 

 mon and Forster's terns are more or less common 

 migrants. The terns are beautiful, graceful birds, 

 the smaller varieties like the Arctic and black 

 resembling swallows in length of wing and general 

 appearance, while the larger ones, like the Cas- 



Bull. No. 185, U. S. Dcpt. Agri., p. n. 



