laying, the eggs to be laid are easily distinguished, as there is a sudden break off in size from the rest, not a gradual decrease. I have tried a good many experiments myself, and have never known a bird continue laying an egg a day beyond the normal number; but have always found that the bird continued laying up to its normal number, and that there was then an interval of a few days (during which, I suppose, the birds paired again) before the next lot was begun. For instance, in the case of a Starling which I experimented upon, there was an interval of five days between the two sets of eggs which it laid. I may mention that a good number of the birds experimented on deserted the nests. It would have been interesting if Mr. Alderson had noticed whether the eggs were fertilized, but I suppose they could not have been so.—Bernard Riviere (Finchley Road, London).
Hours at which some Birds Sing.—In 'The Zoologist' (p. 472), Mr. Riviere touches on a very large subject, which occasionally attracts attention from observers, but which is yet far from having had an exhaustive treatment accorded to it. The hours at which birds begin to sing differ according to the season of the year and according to locality; they are also influenced in some other way, perhaps by weather conditions, as the same species occasionally show a marked difference of time in the hours at which they begin to sing on corresponding dates of different years. Mr. Riviere neglects to give the particular date in April, and thus deprives his note of the value it would otherwise have. In Shetland, during midsummer, no real darkness covers the land, and in consequence great activity prevails by night as well as by day. Larks and Wheatears sing at the hour of midnight, and the former has a long spell of uninterrupted song. Gulls of several species, Snipe, Arctic Terns, and other species of birds, make little difference between night and day, and are ever watchful for and ready to meet any night intruder on their haunts long before he comes near their home. Further south, in the Forth area, for instance, we cannot boast an absence of darkness in summer, and we find that bird-life in the main enjoys a temporary halt every night. Yet even here many species of birds, such as Coot, Little Grebe, Heron, Peeweep, Curlew, Redshank, &c, pay little regard to the succession of day and night. At dawn of day the songsters break forth one by one in song, till the whole grove or moorland rings with their melody. The Lark is the species in this neighbourhood that hails the day, but in the woodlands, where Larks are absent, Blackbird and Thrush generally rival each other in breaking the silence of night. Few things are more interesting to the field-naturalist, or more delightful to him, than the music of the grove, when it succeeds the dismal period of waiting on in the stillness and darkness of night. For several hours he has had little to attract his attention save the hooting and shrieking of Owls, the plaint of the Peeweep, or it may be the terrific yell of a Heron,
