ORNITHOLOGICAL OBSERVATION IN ICELAND. 271 



-only, but T have never myself seen anything but sand-eels brought 

 in to them. In no instance were they fed witii fish from the loch 

 on which they were established, hut only from the sea. 



If we suppose tliat natural selection has, in some cases, lessened 

 the number of young birds in a family, by favouring those couples 

 (and, through them, the race) to whom a sickly child was born 

 (so long, of course, as it died), theu, on the principle, '* Bis dat 

 qui cilo dat," we can understand this sickliness showing itself at 

 an earlier and earlier age, till, at last, the dissolution took place 

 within the egg. Here, then, may be the explanation of a fact 

 that is not the less one because reference is so seldom made to it, 

 viz. that one egg of a sitting is often addled. I believe this to 

 be normal with the Dabchick, as probably also with the Curlew.^ 

 With their brood of four — which I think is the ordinary one — 

 well advanced, there was an unhatched egg in the nest of the 

 Merlins that I have been watching, whilst, from what I can learn, 

 Sea-Eagles here have usually but a single eaglet. I have made 

 the same observation with various other species of birds. 



Birds may derive their fecundity— which originally, perhaps, 

 was greater and more general — from their reptilian ancestry, 

 bat when both the eggs and the hatched young require little or no 

 attention, as is, speaking generally, the case with reptiles, large 

 families are not an incumbrance. With the advent, or increase, 

 of personal concern for the offspring, however, this is no longer 

 the case. The burden now begins to make itself felt, and may 

 for various reasons, become detrimental. The gradual lessening 

 of it, therefore, where this is the case, through the action of 

 natural selection, would not be at all surprising. Such a result 

 might be brought about in a variety of ways, including the 

 destruction of the egg by the parent bird itself — a thing which 

 1 have, in one case seen, and, in others, had to infer. 



It would seem that whilst some of the Phalaropes are 

 sitting, others have either j'et to lay, or have not laid all their 

 eggs. The last might account equally for the attentions still 

 paid by the males to the females and the refusal of them by the 

 latter. The brusquerie of the courtship would also be in accor- 

 dance with the later stage of things, as may be seen in all birds, 

 I think, and notably in the male Pheasant, who, in the earlier 



* Dr. Heatherley has noticed this. 



