(3). If (2) be necessary, the egg must be abnormally large for the size of the bird.
Everyone knows how wonderfully these three difficulties are surmounted.
8. Crakes and Rails.—These birds lay from seven to nine eggs in well-concealed situations amongst the stems of standing grass or grain. Owing to the cover afforded by the stems, the young need not be so large when hatched as the young of the Plover; consequently the eggs are much smaller, and the hen can incubate a greater number. At the same time it is imperative that she should produce a good clutch, for very many nests are destroyed when the grass comes to be mown. The birds are also migratory, and encounter the usual dangers during passage.
9. Game Birds lay a good many eggs, as the situation of their nests lays them open to many enemies—Stoats, Crows, &c. Further, I should not be surprised to learn that they were originally less prolific before they were persecuted under the name of sport. At any rate, the least persecuted species, the Ptarmigan, as a rule lays the fewest eggs.
10. Coming to the order of Natatores, I plead guilty to a very small experience of these birds. It is obvious enough why Razorbills and Guillemots lay but one egg. It is well known that their single egg is of such a tapering form that a gust of wind, instead of sweeping it from the ledge of rock on which it is laid, merely causes it to twist round in a circle with the thin end as centre. If there were more than one egg in a clutch, these gyrations would result in disaster, and a Guillemot's breeding station in a high wind would indeed be a curious spectacle.
It may further be noticed that the largest clutches in this order are those laid by the Teal and Wild Duck, whose nests are accessible to many enemies, and who are not altogether free from the molestation of man.
