The Bird -Life of Cobb's Island 



113 



itself nearly invisible on a bit of sand, where there is no object with which 

 it might be confused, is especially striking. In the newly hatched young the 

 mandibles are of equal length and the characteristic prolonged lower man- 

 dible does not appear to be fully grown until after the bird takes wing. 

 This may be considered as evidence that this specialized character has been 

 developed late in the history of the species, or it may be a correlation in 

 growth which defers the perfection of an organ until it can be successfully 

 employed. Certainly without ability to fly a Skimmer could not ' skim,' as 

 with the longer lower bill cutting the water it takes food from the surface. 



LAUGHING GULL ON NEST 



Until, therefore, the bird can fly its bill enables it to pick up such objects 

 along the shore as might be desirable for food. 



From my blind among the Skimmers I could look out over the marsh 

 where the Laughing Gulls nested. In the morning light the breasts of 

 these birds turned toward the east looked like great white flowers with 

 which the marsh was dotted. They were photographed without difficulty 

 by erecting bundles of grass on tripods near their nests one evening and 

 replacing them with grass-covered cameras the following morning. Ex- 

 posures were made with a thread run to the blind (which now was made 

 to do duty as a musk-rat's nest) a hundred and fifty feet away. The first 

 Gull returned to its nest within five minutes after the photographic 

 apparatus was arranged. 



An A. O. U. warden on Cobb's Island protects the birds from man. 



