THE TORTUGAS LABORATORY 



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cality of its nest, if, however, the nest be raised vertically, the bird, but 

 little disturbed, alights upon it, then if after an interval it be lowered, 

 the bird attempts to alight in the air above the nest in the place where 

 the nest was formerly. A slight horizontal movement of the nest 

 causes great confusion in the bird. 



Professor Watson caused adult birds to be taken from Bird Key to 

 Havana, 92 miles; to Key West, 66 miles, and to Cape Hatteras 850 

 miles from Bird Key. Birds liberated at these places returned in a 

 very short time to their nests on Bird Key. The sooty terns returned 

 from Cape Hatteras in five days, and as they probably flew along shore 

 and not by the straight-line route, they must have flown at least 1,081 

 miles. This is a most striking experiment, for Cape Hatteras is far 

 to the northward of the northern limit of the geographical range of 

 these birds. 



Another Tortugas research was that of Professor Eeighard, of the 

 University of Michigan, who worked upon the subject of warning 

 coloration. 



Por a long time Darwin was puzzled by the fact that many animals 

 are conspicuously colored and yet their habits are such that they openly 

 display themselves to the view of all possible enemies. Why, then, 

 were they not exterminated? That brilliant yet modest man, Alfred 

 Eussel Wallace, came forward with an ingenious hypothesis, now well 

 known as the theory of warning coloration. He assumed that such con- 







Fig. 6. A Noddy Gull upon its Nest, Bird Key, Tortugas. 



