The Zoologist/4th series, vol 1 (1897)/Issue 678/Cuckoos Sucking Eggs

by John Henry Gurney Jr.

 

CUCKOOS SUCKING EGGS.

By J.H. Gurney, F.L.S., F.Z.S.

 

I am glad Mr. Davenport has raised the question of Cuckoos sucking eggs, which, with so many good observers, ought to be definitely settled. To describe them as habitually sucking eggs by choice, as is occasionally done in popular books, is a little misleading, for their primary intent, it must certainly be conceded, is to remove, not to eat them. The Cuckoo's throat is very wide; and if in the operation of moving eggs from some Wagtail's nest an egg slips down, we have what in court would be called presumptive evidence that they by no means object to it. But to charge a Cuckoo with sucking the eggs of Pheasants and Wood Pigeons, and even Grouse (as in the case of the gamekeeper cited by Mr. Storrs Fox), seems absurd. There is nothing to induce a Cuckoo to enter the nests of these birds, and even if they did their shells would be very tough for its feeble bill; while probably Cuckoos would not peck or impale an egg at any time, but rather try to crush it between the two mandibles. I once saw in an open meadow a Cuckoo rise from near a Skylark's nest, from which it had no doubt retreated a few feet on hearing my approach; I immediately went up, and found a broken Lark's egg in the nest. This was evidently the work of the Cuckoo, which may even have been sucking the egg when I came up. There were no other egg-shells in the grass; and if that Cuckoo could have been promptly shot, I should have expected to find the remains of other Lark's eggs in its œsophagus. A gentleman wrote in 'The Field,' under the initials of W.R.G. (I have unfortunately not kept the exact reference), that while he was sitting with a friend in Dorsetshire, in a room looking out upon an ivyclad wall, a Cuckoo passed the window. Knowing that a Pied Wagtail had her nest on the wall, the two observers approached the window, and watched the Cuckoo clinging to the ivy barely four yards away from them. They distinctly saw her take an egg out of the nest, alight with it on the flower-border, and then, throwing up her head and apparently tossing the egg well back into her throat, crush the shell and let the contents trickle down. She then threw out the shell, which was picked up by the observers. If this is not accepted as good testimony, I would draw Mr. Davenport's notice to Mr. Sach's evidence in Dresser's 'Birds of Europe'; and especially to the narration by another correspondent of 'The Field,' H.L.W., who took out of a Cuckoo's crop, near Worcester, the recognisable remains of some eggs, two of which were Robins, and the rest apparently Hedge Sparrows ('The Field,' Jan. 28th, 1882). There is no bird about which so much has been written as the Common Cuckoo; and yet we have not reached the end of its history by a long way, as these stories show.

Dr. Bowdler Sharpe calls the egg-sucking Cuckoo a myth ('Birds of Great Britain,' vol. ii. p. 26); but the foregoing narrative seems inexplicable in any other way, and must be held to prove that, in one instance at any rate, a Cuckoo deliberately ate eggs. That they remove them from the nests of their dupes few will deny; and I have fairly clear evidence that they remove young nestlings as well.

On the 20th of last May I had been listening to the cry of the Spotted Crake on one of our Norfolk "broads," when three old Cuckoos, one behind the other, probably a hen and two cocks, flew past, and then over a small bog-myrtle bush, about two feet high, which stood quite by itself on the fen. In about three minutes one of these Cuckoo's returned, and, either not seeing or heeding me, entered the little bush, where it remained certainly more than five minutes. I approached very cautiously, but found it impossible, in the long grass, to observe it even with strong binoculars.

A subsequent minute search revealed nothing in the bog-myrtle, but about eight feet from the bush was an empty Yellow Wagtail's nest, scattered round which, at distances varying from two to six feet, were five young Wagtails, doubtless dropped where they were by the Cuckoo. I take it that the object of this Cuckoo was by removing the young to make the old Yellow Wagtail build a new nest in which she might also deposit her egg. Probably she was a Cuckoo with a special predilection for Yellow Wagtails' nests, and nothing else would suit her.

Cuckoos would probably be less likely to meddle with Hawfinches' eggs than those of most birds, because the nest of the Hawfinch is very rarely selected by them to lay in. Jays and Jackdaws were more probably the thieves which robbed the thirty-two nests alluded to by Mr. Calvert, assisted perhaps in their depredations by mice, which are very destructive little pests.

Mr. P.N. Emerson, in his 'Birds, Beasts, and Fishes of the Norfolk Broadland' (1895), writes:—"The evidence I have collected from [Norfolk] fenmen and others quite satisfies me that the Cuckoo does suck eggs; and, though I have never caught him, I have found eggs sucked that were whole before the Cuckoo hopped about them.... I have opened several Cuckoos' crops at the beginning of the season, and have upon some occasions found a yellowish substance which looked to me like nothing but egg." With this quotation I leave the much vexed question to those who have better opportunities than I have now of watching this inveterate nest-hunter.

 

We have had two nests this year with two Cuckoos in each; one belonged to a Pied Wagtail, and the other to a Spotted Flycatcher, but from what I can learn one Cuckoo only was reared in each nest.