PREFACE. 



The present series of studies on the behavior of birds is a direct outgrowth 

 of an investigation made on the noddj' and sooty terns nesting on Bird Key, 

 Tortugas, Florida, by the writer under the auspices of the Marine Biological 

 Laboratory of the Carnegie Institution of Washington in 1907 (publication 

 103). The homing " instinct" is the central topic in all the papers. In the 1907 

 investigation the fact appeared that terns possess a homing sense, behaving 

 exactly as do homing pigeons when sent away from their nests and young. 

 Such good subjects did the terns appear to be that it was soon decided to make 

 this homing sense the chief object of the Tortugas researches. The topo- 

 graphical situation of Bird Key makes that island especially suitable for carry- 

 ing out such expesynents. In the first place, it is the northern limit of 

 migration of these tropical birds. It becomes possible there to test whether the 

 birds can home in a region never before, in all probability, visited by them. 

 This can be accomplished by sending the birds anj-where north of Bird Key. 

 Secondly, on account of the fact that Bird Key is the last body of land between 

 the coast of Florida and the coast of Texas, the birds can be sent out for hun- 

 dreds of miles over open water. There is thus afforded an opportunity for 

 testing homing where apparently no "visual landmarks" can exist. These 

 two conditions have never before been realized, and they are conditions which 

 are indispensable in even a preliminary scientific study of homing. 



The 1907 investigation already referred to is concerned largely with instincts 

 in terns — those of feeding, nesting, brooding, etc. It was necessary to have 

 some survey made of these instinctive types of behavior before the homing 

 instinct itself could be investigated. A part of the opening paper, pp. 35-4.5, 

 in the present series gives much additional data on the nesting activi- 

 ties which have a bearing upon the control of experiments on homing. These 

 observations are concerned with the instincts connected with the brooding of 

 the egg, such as the number of shifts at the nest; retention of mate and nest 

 habits; water habits and instincts, etc. It is thought that these observa- 

 tions, when taken in connection with those made in the first study, afford accu- 

 rate means of testing the homing ability in these two species of terns. 



Having made the necessary investigation of the instinctive life of the terns, 

 it became possible to carry out homing experiments. Preliminary experi- 

 ments in 1910 (p. 47) showed clearly that in order to make a success of the 

 work, some well-trained investigator would have to be sent out with the birds. 

 In the 1910 work the terns were sent out with responsible men attached to the 

 laboratory but who had had no training in feeding and caring for them. On 

 account of this, usually something like half of the birds died en route, and the 

 rest were released at the more distant points in very poor condition. In 

 order to meet this difficulty, Dr. K. S. Lashley was asked in 1913 to associate 

 himself with the work. The very successful returns from the second Galves- 

 ton trip (p. 54) are due largely to his care of the birds on the forward journey. 



In addition to his invaluable aid in the problem of distant orientation, Dr. 

 Lashlej' separately began a study of proximate orientation (p. 61), i. e., of the 

 behavior of the terns in locating the nests, mates, young, etc. This paper, in 

 addition to supplementing the work on distant orientation, opens up a wealth 



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