[To the Editor of the SPECTATOR]
SIAM I see two letters in your issue of April 18th, about the colours of cuckoo's eggs. My personal experience of the ways of this most puzzling of birds is as follows : Along the banks of the Thames female cuckoos annex certain territorieswhich include osier beds and lay their nine or ten eggs in the nests of the reed warblers or sedge warblers. For example, a " sedge warbler cuckoo," if I may call her so, had the territory near to Bell Lock, Staines, and a " reed warbler cuckoo " that near Magna Carta Island. The former laid eggs of a brownish tinge, which harmonized with those of the reed warbler, while the eggs of the latter were more green in tint. But since sedge warblers were less common than reed warblers the Bell Lock bird, and others also who preferred sedge warblers as their victims, often had to put up with reed warblers' nests.
In Suffolk and Essex cuckoos seem to prefer pied-wagtails as foster parents, and then their eggs are of a greyish type. Near Tunbridge Wells I was shown some that were laid by birds parasitic on robins and were of a rufous tinge. In Scot- land where probably more than half the eggs of the cuckoos are hatched by meadow pipits one finds quite another type of egg, which matches well with the brown of the meadow pipit. Each bird seems to lay the same kind of egg every year. This was clearly shown in the case of the cuckoos who came to Bell Lock, and to Magna Carta Island. But not unfrequently a cuckoo is unable to find the special nest which she would prefer ready for her and so puts up with another. For example, I have found an egg which would match well with that of a meadow pipit among the blue eggs of a hedge sparrow.—I am, Sir, &c., Salcombe house, Sidm. uth.
J. G.. Coaxisn,
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