MALLEE FOWL. 
laced together, so to speak, prevent the displacement of the whole mass, 
which would crush the eggs were it to start moving in any given direction, 
whilst the eggs would be liable to be broken if subjected to the compression 
of such a weight of sand out of which the Leipoa forms this mound, heaping 
it high above its eggs, and which is of such an unstable nature. The 
forming of the egg chamber occupies the bird for about one and a half hours. 
The vegetable debris thrown out by the formation of the egg chamber is placed 
back into the hole the same day, and being mixed with sand becomes more 
friable and loose. The mound is then heaped up into a pyramidal form, and 
after six or nine days have elapsed the female opens out the egg chamber and 
deposits her egg. To construct a new mound and prepare it for the formation 
of the egg chamber occupies the pair of Leipoa from twenty-five to thirty-three 
days. The birds work at the building of the mound only early in the morning 
for about four hours, and again late in the afternoon for a short time. On 
moonlight nights Mr. McLennan has seen them working for a few hours. The 
energy displayed by these birds in making their mounds is truly marvellous, 
whilst the labour entailed in scraping and gathering together the enormous 
quantity of material which forms it is prodigious. But what is still more 
astonishing is the amount of labour which devolves upon the hen bird every 
time she lays a fresh egg, since she has to scratch out the egg chamber and refiU 
it each time, and as she lays in ordinary seasons about fourteen eggs, she has 
to re-open and refill it fourteen times. This reopening and refilling, together 
with the necessity of repeatedly opening up and refilling the egg chamber after 
the bird has ceased laying, so as to keep the material around the eggs loose, 
whereby sufficient oxygen can be supplied to the embryo in the egg, is a further 
cause of wonderment. The time occupied by the bird in cleaning out the egg 
chamber and preparing it to receive the egg and refill it again, after depositing 
her egg, takes the hen from three-quarters of an hour to one hour. Occasionally 
the cock assists the hen to open out the mound. About nine o’clock a.m. the 
Mallee hen visits her mound, and between that hour and ten o’clock a.m. she 
lays her egg. The same mound is not used every year by its original architects, 
since the Leipoa does not breed every season. In Victoria during the ^onths 
of April and May the birds usually start to dig out the old mound, or else 
construct a new one. The date of commencement varies according to the season 
and locality, but the governing factor is the rainfall, on which the Leipoa is 
dependent for the moisture to soak the vegetable material of the egg chamber, 
as well as the subsequent food-supply. During periods of drought egg-laying 
is suspended, and although a season may have started propitiously, yet 
should a dry atmospheric condition manifest itself, the Leipoa leaves ofi 
depositing its eggs, influenced no doubt by the change wrought in the food- 
supply, as weU as by the condition of the vegetable material of the egg chamber, 
49 
