M. Faber oti the Breeding Spots of Birds. 2l 



of feathers from one or more spots of the belly on the develop- 

 ment of the pairing impulse, and before they have laid any eggs, 

 or have begun to hatch. This gives rise to certain naked spots, 

 which I call Breeding spots. The utility of this arrangement 

 is various. There is generally so thick a layer of feathers upon 

 the belly of most aquatic birds, that without some process of this 

 kind, the eggs would hardly ever be brought directly in contact 

 with the skin of the mother. In the second place, most aquatic 

 birds have no nest, or other means of furnishing warmth to their 

 eggs, €ven in the coldest climates. The breeding spots thus 

 form as it were a nest on the body of the parents, as they collect 

 with their bills all the eggs into this artificial cavity, so that they 

 are quite surrounded by the feathers. 



The discovery of this peculiar phenomenon in the history of 

 the boreal birds is entirely my own. Only occasionally do we 

 find former writers directing our attention to these breeding spots, 

 but none seem to have recognised their real importance. Being 

 only found in the boreal birds, the discovery was reserved for 

 a naturalist who had an opportunity of spending the summer in 

 their native haunts. Gunnerus remarks of the Procellaria gla- 

 cialis*, that he had found no such cavity, but that the medical 

 student Martin had observed -f- them to possess a hole under the 

 crop beneath the large feathers, which he thought might per- 

 haps serve for the hatching of eggs. Fabricius remarks, also of 

 this bird if, that he had found this hollow ; his words are, Aream 

 deplumem sub abdomine etiam reperi. M. Boie has observed, 

 in his Travels (p. 192), which were written at the same time 

 with my Prodromus, with respect to the Lestris parasitica, that 

 this bird lays only two eggs, and shews that the two parents, 

 which sit alternately, have on both sides of the belly a naked 

 spot, of the size of one of the eggs, and the editor hazards ihe 

 conjecture that these naked spots may be found in many others 

 of the aquatic and wading tribes. 



The true uses of these spots I shall now endeavour to un fold- 

 Birds seldom pluck off' their feathers in order to lay them in the 

 nest. Those which are most naked of all during the breed- 

 ing season, either build no nest, or have no feathers in it. Only 



• Mem. of the Drontheim Soc. i. 198. 



t Transact, of the Royal Acad, of Sciences of Sweden for \ToV, 



X Fauna Groenlandica, p. 86. 



