HISTORICAL AND EXPERIMENTAL STUDY OF HOMING. 39 



SWIMMING AND RESTING UPON THE WATER. 



In an earlier paper we called attention to the fact that the birds during the 

 nesting season, even while feeding upon minnows over the surface of the water, 

 rarely come to rest in the water, and that neither the noddy nor the sooty is 

 ever seen swimming in the water. Since, in the experiments on homing, it is 

 necessary for the birds sent to Galveston and out over the Gulf generally to be 

 able to pass one or more nights upon the water, it occurred to us to make some 

 tests as to the swimming ability of the birds, their ability to rest on the water 

 over night, etc. We report the following notes made by the senior author 

 in 1910: 



TESTS UPON THE W.\TER HABITS AND INSTINCTS OF NODDY AND SOOTY TERNS. 



1. One noddy and one sooty were carried into the water and gently placed on the surface 

 of the water. They arose with ease and flew away, none the worse for the test. 



2. One noddy and one sooty were held in the water and at times immersed in it for a period 

 of 10 minutes. The birds were then placed gently on the surface. The noddy immediately 

 raised itself and flew over to the land. The sooty was helpless under these conditions. 

 While in the water it floundered about, getting the tips of its wings out, but could not rise. 

 Since it was becoming more and more water-logged, I rescued it and tossed it into the air. 

 It immediately righted itself, and, gathering strength, rose higher and higher and flew away. 

 When in the water the bird made no attempt to swim, nor did it turn instinctively towards 

 the shore. 



3. Two noddies were captured and carried into the water and plunged below the surface 

 to a depth of 2 feet and released. When they reached the surface, both rose easily and flew 

 away. 



4. A large wire cage, 6 by 8 by 7 feet, having a 2-foot door, was carried into the water 

 to a distance of 100 yards from the shore and left there during the test to be described. 

 The cage was entered through a wire door in the side. It was sunk to a depth of 2 feet. 

 This left .5 feet between the surface of the water and the top of the wire door. (See plate 5.) 

 Two noddies and two sooties were placed in this cage at S"" 1.5™ p. m. They began flying up 

 and attempting to get out. All were able to aUght on the water and to rise from it, the 

 noddies in a beautifully coordinated way. When they ahghted they would fold their 

 wings carefully and tightly against the body and hold the head and breast high above the 

 water, swimming as smoothly and as beautifully as a swan, and showing perfect at-homeness 

 in the water. (See plate 5, fig. 1.) The sooties, on the other hand, arose and ahghted 

 clumsily — head barely out of the water, wings not held up — sometimes, indeed, they were 

 spread out. The sooties, however, could swim perfectly. For about 2 hours the birds 

 attempted to fly out, the noddies making the more vigorous resistance. The birds then 

 became relatively quiet. I left them undisturbed until 8'' 30" the following morning. 



The noddies were in first-class condition at that time and were not in the shghtest degree 

 bedraggled or water-logged. They swam as easily and as perfectly as in the afternoon of the 

 day before. As I approached the cage, they arose and hovered for more than a minute in 

 the air, then alighted. I opened the door and the birds swam out and rose immediately 

 from the water, one going at once to its nest, the other out over the water. One sooty was 

 dead; the other was just barely able to keep its head above water; the feathers were 

 water-soaked and the bird was shivering. Plate 5, fig. 1, shows the condition of the birds 

 at this time. The two noddies are in perfect condition. The one hve sooty is shown in 

 the left-hand corner of the photograph. I rescued it and put in on the warm sand, where it 

 remained and slept without moving from its tracks for nearly 2 hours. A commotion in 

 the colony then alarmed it and it arose and started out over the water. It flew to a dis- 

 tance of 100 yards and fell into the water. The other birds of the neighborhood imme- 

 diately began to hover over it in the pecuhar way shown in our earher study. I swam out 

 and rescued the bird, tossing it high in the air. It flew the remaining distance to the shore 

 and again sunned itself for more than an hour. 



5. Two noddies and two sooties were put into the cage as before, this time at 11 a. m., 

 so that I might be able to watch their behavior and rescue the birds in case of disaster. The 

 island was generally quiet and I watched them through a field-glass so that I might not 



