300 ANlSnJAL REPORT SIVHTHSONIAN INSTITUTION, 1940 



Most birds incubate their eggs and care for their young, but the 

 maleo fowl or mound-building bird {Alectura and related genera) 

 of Australia, New Guinea, and the Philippines, have found a unique 

 short-cut in incubating their eggs. The parents, using their feet 

 and possibly their beaks, scratch together a mound of dead vegeta- 

 tion in the forest. Sometimes several pairs of birds will cooperate 

 in the building of a mound as much as 30 feet long and 5 feet high. 

 They tlien dig holes in the mound and lay their eggs in them. The 

 heat generated by the decaying vegetation is sufficient to incubate 

 the eggs. When the eggs hatch the young birds scratch their way 

 to the surface and sliift for themselves, never knowing their parents. 

 The chicks are able to fly immediately on emerging from the mound. 



On the other hand, there are many birds, such as the pelicans, 

 that nest on barren rocky or sandy locations where the heat may 

 be intense. They incubate their eggs when the temperature is not 

 too high; but if the heat becomes too great they stand above the 

 nest and shade it with their bodies. 



Emperor penguins are large sea birds of the Antarctic region. 

 They inhabit areas that are almost solid ice and snow wdth only 

 occasional outcroppings of bare rock. Continuous darkness accom- 

 panied by intense cold and violent storms prevails for months at a 

 time within the Antarctic Circle. Even in summer the weather con- 

 ditions are not favorable for rearing families, and the best weather 

 is of short duration. These penguins have, therefore, evolved a 

 unique method of perpetuating their kind. Even if they laid their 

 eggs very early in the springtime, the young would not be hatched 

 until the summer was so far advanced that they would not have time 

 to become well grown before the rigors of their first Antarctic 

 winter set in. Therefore, the emperor penguins lay their single egg 

 during the cold and darkness of the Antarctic night. They then in- 

 cubate it by keeping the egg on their feet between their thighs so 

 that it does not touch the ground, snow, or ice. The birds are so 

 zealous in their care of the e.gg that male and female w'ill at times 

 actually fight to care for it. In this way, the egg is made to hatch 

 in the Antarctic springtime so that the little one has the benefit of 

 the full Antarctic summer during its tender period. By fall it will 

 have become a husky youngster, ready to face the rigors of the 

 Antarctic winter. 



Some reptiles lay eggs that are hatched by the heat of the sun 

 and the warmth of the sand or of decaying vegetation, the young 

 ones never knowing their parents. Others give birth to living young. 

 Apparently there is no clearly defined dividing line between the 

 oviparous and viviparous groups of reptiles, for among nearly related 

 horned lizards both types of reproduction are found. Some species 



