So much for the generative processes in snakes and insects, and
also in oviparous quadrupeds. Birds without exception lay eggs, but
the pairing season and the times of parturition are not alike for all.
Some birds couple and lay at almost any time in the year, as for
instance the barn-door hen and the pigeon: the former of these
coupling and laying during the entire year, with the exception of
the month before and the month after the winter solstice. Some hens,
even in the high breeds, lay a large quantity of eggs before brooding,
amounting to as many as sixty; and, by the way, the higher breeds
are less prolific than the inferior ones. The Adrian hens are
small-sized, but they lay every day; they are cross-tempered, and
often kill their chickens; they are of all colours. Some
domesticated hens lay twice a day; indeed, instances have been known
where hens, after exhibiting extreme fecundity, have died suddenly.
Hens, then, lay eggs, as has been stated, at all times
indiscriminately; the pigeon, the ring-dove, the turtle-dove, and
the stock-dove lay twice a year, and the pigeon actually lays ten
times a year. The great majority of birds lay during the
spring-time. Some birds are prolific, and prolific in either of two
ways-either by laying often, as the pigeon, or by laying many eggs
at a sitting, as the barn-door hen. All birds of prey, or birds with
crooked talons, are unprolific, except the kestrel: this bird is the
most prolific of birds of prey; as many as four eggs have been
observed in the nest, and occasionally it lays even more.