Sources : Peahen

Pliny the Elder [1st century CE] (Natural History, Book 8, 28): The peahen begins to lay when three months old. In the first year it lays one egg or a second one, but in the following year four or five at a time, and in the remaining years twelve at a time, but not more, with intervals of two or three days between the eggs, and three times in the year, provided that the eggs are put under farmyard hens to sit on. The male peacock breaks the eggs, out of desire for the female sitting on them ; consequently the hen bird lays at night, and in hiding or when perching on a high place - and unless the eggs are caught on a bed of straw they are broken. One cock can serve five hens, and when there have been only one or two hens for each cock their fertility is spoiled by its salaciousness. The chickens are hatched in 27 days or at latest on the 29th. - [Rackham translation]