124 The Irish Nahiralisf. June, 1912. 



performances of the Long-eared Owl, the Woodcock, and even the Lap- 

 wing, are cases in point — there is room for doubt in all as to whether 

 cries and acts described by different observers have been either wrongly 

 identified or else wrongly differentiated. It is certainly quite at variance 

 with the present reviewer's experience to learn that the " moaning 

 sounds " which are uttered in spring by the male Long-eared Owl are 

 " made, it would seem, on the wing, and accompanied by a strange 

 percussion of the wings brought smartly over the back." In our 

 experience the moaning notes are uttered only while the bird is at rest 

 on a branch, the flight being silent except for the frequently heard wing- 

 claps with which he plays about his haunts. 



One of the most interesting of Mr. Kirk man's chapters is that on the 

 Cuckoo, as to whose parasitic habits he, however, declines to commit 

 himself to an explanation. Some space is also devoted to this bird's 

 practice of ejecting one or more of its victim's eggs when placing its own 

 in a nest ; and the reason for this act is also regarded as an unsolved 

 puzzle. Here we think Mr. Kirkman has overlooked at least a fairly 

 probable explanation. At the present time the ejection of an egg or 

 two from the nest where the Cuckoo's is deposited may be of little use — 

 though it is, perhaps, not altogether unimportant to the infant Cuckoo 

 to have the laborious task of removing all its foster-brothers and sisters 

 from the nursery somewhat reduced for it in advance, by the removal 

 of a few of them in the egg-stage. But we must remember that the 

 parasitic habit almost certainly originated with Cuckoos whose young 

 had not yet acquired the instinct of ejecting their fellow-nestlings, and 

 would have to be reared along with them, as the young of some foreign 

 Cuckoos are to-day. Under those circumstances would it not be obviously 

 to the advantage of the young Cuckoo that the family with whom it 

 would have to share its rations should not be too large ? The parent 

 guarded against the danger by throwing out an egg or two, and retains 

 the habit of doing so — a habit that is even now probably not quite 

 useless — to the present day. 



In his chapters on the Razorbill and Guillemot Mr. Kirkman raises 

 several general questions which he ultimately leaves in a spirit of 

 philosophic doubt. On the subject of the extraordinary amount of 

 variation in the colouring of the Guillemot's eggs he, however, falls back 

 on Wallace's explanation that it is due to the simple negative fact of 

 natural selection having here ceased to operate, no special colour being 

 more protective than another on the lofty and many-coloured cliff-ledges 

 along which Guillemots nest. He thus rejects the explanation — favoured 

 in the " Birds of Ireland " by Mr. Ussher — that the varied colours enable 

 each Gtiillemot to know her own egg. It will be seen that Mr. Kirkman's 

 view implies a belief that natural selection must still be actively at work 

 in checking the tendency to variation in the eggs of nearly all other known 

 species of birds, except the absolutely white. This is to set a very high 

 value on the utility of the colours of eggs in general ; and we trust that 

 Mr. Kirkman will return to this deeply interesting question at some 

 other stage of his work. 



C. B. M, 



