22 M. Faber on the Breeding Spots of Birds. 



the Anas and Sula tear out their feathers to line their nests. 

 Therefore, we do not find in the nest the feathers which have 

 been taken off the body of the bird. It is necessary that a por- 

 tion of the great mass which covers the abdomen be removed, in 

 order that the eggs come into immediate contact with the epi- 

 dermis. This is the first use of the breeding spots. It cannot, 

 however, be their only use, because they are wanting in many 

 of the aquatic birds of the compound monogamy, whose coat of 

 feathers, as just mentioned, is no thinner, as in the Sula and 

 Carlo. They must, therefore, be intended to envelope and fur- 

 nish the eggs with warmth. 



I have found these breeding spots only in the boreal aquatic 

 birds, and confined to those species which belong to the perfect 

 or compound monogamy. It would be extremely interesting if 

 their existence could be established in the aquatic birds of other 

 zones *. They are never found in the genera Colymhus and Po- 

 dkeps^ which belong to the partial monogamy. They are equally 

 wanting in those simply monogamous, as the Mergus^ Anas, 

 Anser, Cygnns. But all these birds have the habit of plucking 

 out their feathers for the purpose of lining their nests, which 

 does not exist in those birds which belong to the perfect mono- 

 gamy, such as the Phalaropus^ Uria, Alca, Mormon, Carlo, 

 Pujffinus, Sula, Sterna, Larus, Lestris, and Procellaria. Breed- 

 ing spots are found in all these genera, with the exception of the 

 Sula and Carlo. 



As both male and female of these species share the labours of 

 hatching, the breeding-spots are found in both sexes, with the 

 remarkable exception, however, of the Phalaropus, where they 

 exist only in the male f. Among the many hundred individuals 



• Since the above was written, I have had an opportunity of ascertaining 

 the existence of these breeding-spots in the Danish gulls and sea-swallows, 

 during a zoological excursion in the summer of 1824. They exist both in 

 the male and female of the Larm argcntatm, L. ridibundus, Sterna arctica, cas- 

 pia^ nigra, and minuta. Their position and number is the same as in the 

 northern individuals of these species. In some wading birds, of both sexes, 

 as the Charadrius hiaticula and albifrons, I found a spot in the middle of the 

 abdomen, besides a thinner cover of feathers on the breast, which they have 

 in common with most land birds, and the other wading birds, at the breeding 

 season. 



I M. Holbol has since assured me that, in Greenland, he has not only 

 found the breeding-spota solely in the male of the genus, but that he never 

 saw a female at the breeding-place. But 1 have found both mates together at 

 the nest in Iceland, but the male only sitting on the young. Can we infer 



