22



T. P. Bellchambers—The Mediae Fowl of Austredia



forward, opens her wings, slightly withdraws her head, and with that

movement the large pink egg slips into its prepared place. Her part is

now done — she quietly glides away into the shade of a bush. The male

now gives his attention to the egg, which has probably fallen a little

out of the perpendicular. Choosing a spot about an inch away from the

egg, he thrusts his beak into the sand up to his forehead, then pushing

forward and using this sand as a cushion, he brings the egg to an upright

position. With the withdrawal of his head the sand falls and keeps

the egg upright and on its small end, in contact with the solid wall

of heating material. The reason for this action is twofold ; first, the

shell is too fragile for direct contact with the bird’s head, and second,

the falling sand prevents the egg from again falling forward. All eggs

in the egg-chamber must be so placed that the chicks emerge in the

right direction to gain their liberty. On their sides they would meet

their death against the hard walls of the egg-chamber. The male now

replaces the blanket of sand and fine leaf-material, sometimes covering

the eggs to a depth of about two feet. The thickness of this covering

has been noticed to vary with weather conditions. This hard and

laborious work during the heat of the day is done in several shifts,

and intervals of rest are taken. The period of incubation is about fifty-

five days. The heat required is from 85 degrees to 96 degrees Fahr.

The eggs are laid at intervals varying from three to seven or even eight

days. The number is aBout thirty, varying according to the age of the

bird and the season. There is also a big variation in the incubation

period, the extreme noted being in one case ninety-nine days. This

must have been due to retarded incubation.


In addition to bottom heat, a very frequent use is made of solar

heat, the mound being frequently opened out to within an inch or two

of the eggs, and, as the material gathers heat, it is replaced layer by layer,

the intervals allowing for the next layer to become heated. I have seen

the. male putting on extra covering by moonlight as late as 8.30 p.m.

on the approach of a change in the weather. This is done to conserve

the heat that has been gathered during the day.


Both birds frequently test the heat of the egg-chamber. This is

done by thrusting the beak up to the forehead into its walls, and holding

it there for several seconds. I think they are guided by this test as to

the amount of sun heat required.



