nests and egg, at times by the female, more often by others of the flock, and the killing of the young birds, after they leave the nest, by the old males, explains in part the slow increase in the flock.
When the pigeons show signs of nesting, small twigs are thrown onto the bottom of the inclosure; and, on the day of our visit, I was so fortunate as to watch the operations of nest building. There were three pairs actively engaged. The females remained on the shelf, and, at a given signal which they only uttered for this purpose, the males would select a twig or straw, and in one instance a feather, and fly up to the nest, drop it and return to the ground while the females placed the building material in position and then called for more.
In all of Mr. Whittaker's experience with this flock he has never known of more than one egg being deposited. Audubon, in his article on the Passenger Pigeon, says: "A curious change of habits has taken place in England in those pigeons which I presented to the Earl of Kirby in 1830, that nobleman having assured me that, ever since they began breeding in his aviaries, they have laid only one egg." The eggs are usually laid from the middle of February to the middle of September, some females laying as many as seven or eight during the season, though three or four is the average.
The period of incubation is fourteen days, almost to a day, and, if the egg is not hatched in that time, the
