HISTORICAL AND EXPERIMENTAL STUDY OF HOMING. 35 



HISTORY OF THE TORTUGAS NODDY AND SOOTY TERN COLONIES. 



The noddy tern (Anous stolidus) and the sooty tern (Sterna fuliginosa) are 

 well known in tropical and jiLxtatropical waters. The colony which is to be 

 found in the Tortugas from May to September was described by Audubon 

 in 1837. He states that at the beginning of May the noddies collect from 

 all parts of the Gulf of Mexico for the purjoose of returning to one of their 

 breeding places on one of the Tortugas called "Noddy Key." They nearly 

 equal in number the sooty terns, ivhich also breed on an island a Jew miles dis- 

 tant. He later describes the sooty teni as nesting on Bird Key. In regard to 

 the number of sooties he says : 



As the chain grated the ear I saw a cloud-like mass arise from Bii-d Key, from which we 

 were only a few hundred yards distant, and in a few minutes the yawl was can'ying myself 

 and my assistant ashore. On landing I felt as if the birds would raise me from the ground, 

 so thick were they all aroimd and so quick the motion of their wings. Their cries were 

 indeed deafenmg, and yet not more than half of them took to their wings on our arrival, 

 those which arose being chiefly male birds, as we afterwards ascertained. We ran across 

 the naked beach and as we entered the thick cover before us and spread in different direc- 

 tions we might at every turn have caught a sitting bird or one scrambhng through the bushes 

 to escape us. 



Since Audubon's time the islands have changed considerably in form. 

 Only noddy and sooty terns (with a few least terns, which breed upon Logger- 

 head) breed in the Tortugas, and these appear only upon Bird Key. Further- 

 more, in 1907, there were 13 times as many sooties as noddies. This island is 

 now somewhat triangular in shape and has an area of about 6,000 square 

 yards (see plate 1; also fig. 2, p. 62). It is covered with bay-cedar bushes, 

 cactus, and various low-growing vines (plate 2). It stands about 6 feet 

 above mean tide level. Plate 1 gives the general appearance of the island 

 at low tide. The small buildings were formerly used in the hospital service 

 of Fort Jefferson. They are now used by the warden. Northeast of Bu-d 

 Key, about Ij statute miles distant, stands the now deserted Fort Jefferson 

 (Garden Key). In this fort is to be found a reef light about 50 feet in height. 

 To the west of Bird Key lies Loggerhead Key, about 3 statute miles distant. 

 This is the largest island in the group. Upon it is to be found a first-class 

 light-house, with revolving light 151 feet in height. Certain other small 

 islands and reefs are to be found near Bird Key. The deep waters of the 

 Gulf of Mexico surround the group as a whole. Eastward of Bii-d Key, about 

 65.8 statute miles distant, lies Key West. Between Bird Key and the environs 

 of Key West are found in order Rebecca Shoals lighthouse and the small 

 islands, Marquesas and Boca Grande. On the westward side one finds only the 

 waters of the Gulf until the shore-line of Texas is reached, Galveston being 855 

 statute miles distant. This strip of open water proves a magnificent route 

 for homing experiments. Figure 1 shows the topographical relations in the 

 Gulf region. 



RESUME OF INSTINCTIVE LIFE OF COLONIES. 

 In our previous paper (Watson, J. B., opus cit.) we gave a detailed account 

 of the nesting behavior of the noddy and sooty. In this connection, we wish 

 simply to supply a summary of certain of our observations bearing upon the 

 instincts and habits which are coimected directly with homing or with the 

 control of experiments upon homing. A large amount of new material has 



