The Mound -Building Birds of Australia 5 



upon her and her mate in dismantling and rebuilding the mound on each 

 occasion of laying. A dweller in the Mallee country, who has enjoyed 

 exceptional experiences with Mallee Fowls' mounds, informs me there 

 are always four eggs in the bottom tier, but sometimes six in the other 

 tiers, except the topmost, which finishes with one egg only; the number 

 of tiers being usually three, occasionally four. 



During laying time, an egg is deposited every third day between 9 and 

 10 o'clock in the morning, or perhaps two eggs a week. A mound con- 

 taining eggs is somewhat cone-shaped in dull or wet weather, but in warm 







EGG- MOUND OF THE MALLEE FOWL 

 From a photograph by Dr. C. S. Ryan 



and sunny days the top is hollowed out (usually about 10 o'clock A. M.), 

 like a miniature extinct volcano, though not exposing the eggs. This en- 

 ables the heat from the sun to penetrate about the eggs; therefore when 

 the mound is filled in again (usually about 3 o'clock P. M.), the heat so 

 absorbed is retained for a lengthened period. I once took the temperature 

 of a mound near the eggs which registered ninety-three degrees. The 

 egg is abnormally large compared with the size of its parents, and measures 

 about three and five-tenths by two and three-tenths inches, weighing about 

 six and one-half ounces. The shell is thin, elliptical in shape, and ex- 

 teriorly of a beautiful soft pinkish red. As incubation proceeds, the eggs 

 become stained, and a thin epidermis chips ofif. In two instances the term 

 of incubation was (as nearly as could be ascertained in the bush) thirty - 

 eight and forty-one days, respectively. From the position (large ends 



