LIFE HISTORIES OF NOBTH AMERICAN GULLS AND TEENS. 



305 



Still another marked change occurs in the habits of the birds. The male no 

 longer feeds the female. Each bird takes equal turns at brooding the egg. My 

 attention was first called to this while I was watching the habits of the birds 

 before the egg was laid. Several nests in the vicinity of the place of observa- 

 tion already contained eggs. ' At: these nests I wag never able to observe the 

 feeding of the female by the male. : At this period the two birds became prac- 

 tically automata. Their life is taken up in alternately brooding the egg and 

 in feeding. The birds spend little or no time together except at night. The 

 one comes to the nest ; the other flies away to feed. 



The egg is generally covered day and night. Occasional trips are made to the 

 water for drlpldng and for wetting, the breast feathers. This latter reaction 

 has its value possibly in' keeping the egg at the proper temperature. The sun 

 is so hot that if the egg 'were left ' uncovered for any great length of time it 

 probably would not incubate. " 



The period of incubation is 35 or 36 days. 



Professor Watson (1908) conducted some interesting experiments 

 to test the ability of the birds to recognize their mates, their eggs, 

 and their nests. Painting or dyeing the plumage disturbed them 

 greatly and upset their powers of recognition, but they were " not at 

 all affected by changing the hue, brightnessj and markings" of the 

 eggs, showing that the egg itself is not recognizable. The noddies 

 were very much puzzled by moving the nest, which shows that it is 

 not the nest that they recognize but its position. 



After the young bird is hatched the parents are still more inter- 

 ested in defending the nest. " They will now attack with vigor other 

 noddies which approach too near the nest — the sooties and the frigate 

 birds." Both parents help in feeding the young coming alternately' 

 at intervals varying from two to four hours. Professor Watson 

 (1908) further sayS: "'- ■ ' 



The young are cared for in the nest until they become strong enough to leave 

 it and live upon the ground. The young birds born In low nests, even at a 

 very early age (20 days and even earlier) clamber from them with alacrity 

 and hide in near-by bushes when danger is imminent. In many cases these 

 young birds can not get back into the nest. Under these circumstances they 

 remain near the nest locality, and the parents on returning first align t on or 

 near the nest and' later hop to the ground and feed the young bird. It is inter- 

 esting to speculate upon the method of recognition between parent and young. 

 There can be rid doubt at least of an accurate functional recognition. Since 

 the noddy is always silent when contented, the evidence is good that recognition 

 occurs wholly in terms of Vision. Whether recognition of young (or of mate by 

 mate> would take place outside of the nest locality is a problem which oueht 

 to be solved. • < 



An entirely different method of nesting has been noted by several 

 observers in the West Indies. , Mr. George N. Lawrence (1864) pub- 

 lished the following interesting notes made by Dr. A. A. Julien on 

 the island of Sombrero : 



Theirnests are of two kinds: For the first the noddy gathers together, by 

 carrying i n its bill, a considerable quantity of bits of shells, deposits them* n a 

 shallow cavity of the rock, say 8 to 12 inches in diameter, deepens a littte tho 



