196 Papers from the Marine Biological Laboratory at Tortugas. 



nest-site, but since it occurred late in the season and did not lead to a com- 

 pleted nest I advance it tentatively: 



One day I observed several noddies " sunning " upon the wire covering- 

 of one of my large experimental cages. Suddenly, one of the birds (male) 

 began nodding^ and bowing to a bird standing near (female). The female 

 gave immediate attention and began efforts to extract fish from the throat 

 of the male. The male would first make efforts to disgorge, then put the tip 

 of the beak almost to the ground and incline it to the angle most suitable to 

 admit her beak. She would then thrust her beak into his (the ordinary 

 feeding reaction). The feeding reaction was alternated with the nodding. 

 After this series of acts had been repeated 20 times, the male flew off and 

 brought a stick. He deposited this near the female and then again offered 

 to feed her. She again tried to feed, then the male attempted sexual rela- 

 tions. She immediatel}- flew away, but almost immediately returned and 

 alighted at a slightly different place. The male again brought the stick 

 and again bowed and offered to feed her. She accepted the food, but again 

 flew away when the, male attempted to mount her. At this juncture the 

 island was disturbed and my observations could not continue. 



If the above is a genuine case of mating, the process is very simple. It 

 consists in the female's accepting food from the male and engaging in 

 sexual relations with him at a given nest locality. Such a process might well 

 take place en masse during the first few hours after the birds alight on the 

 island. I was not fortunate enough to obtain a corresponding set of obser- 

 vations of even this unsatisfactory kind upon the mating of the sooties. 



THE CHOICE OF THE NEST-SITE, AND THE MATERIAL USED IN 

 CONSTRUCTION OF THE NEST. 



THE NEST OF THE NODDY. 



The noddy constructs its nest from (i) loose dead branches of the bay- 

 cedar bushes; (2) of seaweed; (3) of a combination of these; (4) of a com- 

 bination of either or both of these with various kinds of sea-shells and coral. 

 When the shells and coral are employed, they are often placed as an inner 

 lining to the nest and the egg is deposited directly upon them. The nest 

 itself is a quite variable structure, and usually loosely put together. It is 

 very shallow, and this is rather singular, since the wind often blows the egg 

 or the young to the ground (see figs. 4, 5, 6, and 7, plate 2). 



The nests remaining from year to year are utilized by the birds at suc- 

 cessive nesting periods ; whether or not by the same pair can not with cer- 



^This nodding reaction is one of the most interesting and ludicrous acts of the 

 noddy tern. It is quite elaborate. Two birds will face each other, one will then bow 

 the head almost to the ground, raise it quickly ahnost to a vertical position, and then 

 quickly lower it. He will repeat this over and over again with great rapidity. The 

 other bird goes through a similar pantomime. If a stranger bird alights near a group, 

 he salutes those nearest, and is in turn saluted by them. During the pantomime a 

 sound is rarely made. 



