46 HOMING AND EELATED ACTIVITIES OF BIRDS. 



a portable cage. When enough birds have been collected the lot is taken back 

 to the house and marked with oil paints as indicated by the cards attached to 

 the bu-ds' necks. Plate 6, figs. 1 and 2, show also the clearness with which the 

 markings appear after the return of the bird. Not until 1913 did we realize 

 the importance of having individual compartments of large size in the carrying 

 cage, and although we used incUvidual compartments in 191.3 they were not 

 large enough, so that it may safely be said that none of the experiments to be 

 reported has been carried out under ideal conditions. Certainly if any other 

 work is ever to be attempted at Bird Key it is absolutely essential to have 

 a large compartment for each bird, and a supply of minnows sufficient to last 

 the whole trip. The most convenient way to perfect the technique of feeding 

 the birds on the trip is to send a refrigerator with the birds and to keep the 

 minnows stored in this. 



PREVIOUS EXPERIMENTS ON HOMING AT TORTUGAS. 



In order that the present paper may give a complete record of the homing 

 work done at Tortugas, we copy the following summary from the 1907 publi- 

 cation. 



Experiment I. 



Six noddies were captured one evening and marked characteristically and individually 

 with oil paints. These birds were put on board the laboratory launch, which happened to 

 be making a trip to Key West on the following morning. The nests of these birds were all 

 close together and were tagged with a large card in order to facihtate observation. Two of 

 the birds were released at Rebecca Shoals Light, 31.38 km. (19. .5 statute miles) from Bird 

 Key; two at Marquesas, 72.75 km. (44.7.5 statute miles); and two at Key West, 106.02 km. 

 (6.5.8 statute miles). I kept their nests under constant observation the whole day long. 

 Naturally, since the birds had been without food for some time, and since 1 had no guar- 

 antee that they would immediately seek the nest after reaching the island, I expected the 

 return to the nest to be irregular. The results were as follows: 



The two Rebecca birds, released at O*" 30" a. m., returned about 12 noon. 



The two Marquesas birds, released at 2'' 15" p. m., returned together at 4 p. m. 



The two Key West birds were released at 6'' 30" p. m. One returned at 7'' 30° a. m. the 

 next day, the other at o"" 05" p. m. These two birds, bearing out my statement that these 

 terns do not fly at night, probably slept in the neighborhood of Key West and left early the 

 next morning. A heavy gale and rainstorm set in very shortly after these birds were re- 

 leased and I doubted very seriously whether they would ever return. Apparently one of 

 the birds was not affected by the storm, whUe the other was probably blown from its course. 

 The respective mates of these birds remained on the eggs the entire time, going neither for 

 food nor water (7). 



Experiment II. 



Three noddies and two sooties (one of the sooties was known to be a male) were captured 

 and marked as above. Their nests were likewise prominently marked. On the early 

 morning of Thursday, June 13, these birds were put into a large insect cage and given in 

 charge of Dr. H. E. Jordan, who was returning to New York. He carried these birds via 

 the government tug to Key West. There food was purchased for them (miimows). At 

 3 a. m. Friday the 14th, Dr. Jordan boarded the Mallory boat Denver, which left at that 

 time for New York. On board the boat the birds were both watered and fed. On Sunday, 

 the 16th, at O"" 20" a. m., the birds were released at lat. 35° 8', long. 75° 10' (12 miles 

 east of Cape Hatteraa, approximately). The wind was fan- for several days after the birds 

 were released. I kept their nests under constant observation, but had almost given up hope 

 of their returning when, to my surprise, on June 21, at 8'' 30° a. m., I found both marked 

 sooties on their respective nests. 



None of the marked noddies was ever found on its old nest, but several days after the 

 sooties had been observed at their nests, by chance I observed one of my marked noddies 



