OBSERVATIONS ON THE GROWTH RATE OF THE FOOT 

 IN THE MOUND BIRDS OF THE GENUS MEGAPODIUS 



By Herbert Friedmann 

 Curator, Division of Birds, United States National Museum 



Among terrestrial birds the feet are generally relatively larger or 

 more powerfully developed than in comparable arboreal forms, but 

 there are few carinate birds with larger, more powerful feet than 

 the megapodes. The uimsual development of the feet in this group 

 has been assumed to be correlated with their scratching habits, 

 especially in making the mounds of decaying matter or in excavat- 

 ing the holes in the sand, as the case may be, in which they lay their 

 eggs. Certainly few birds, even those that burrow in the ground, 

 have more need of large, strong feet than the megapodes. In this 

 family of birds, however, the case is somewhat different from that 

 obtaining in other groups in that not only do the adults use their 

 feet in digging, but the young have to dig their way up to the surface 

 on hatching. In no other group of birds do the newly hatched young 

 have such immediate need of strong feet. Consequently it seemed 

 that a study of the feet of young and adult birds might show some- 

 thing of interest in helping to understand some fragment of the 

 puzzles that the life histories of the megapodes present. 



Recently the United States National Museum received a fine series 

 of alcoholic specimens of Megapodius pritcJiardl collected by Lieut. 

 Henry C. Kellers, United States Navy, on Niuafou Island, one of 

 the Tonga group. Among these there were two chicks and one em- 

 bryo nearly ready to hatch, as well as a large number of adults of 

 both sexes. The embryo is remarkable in that while it is in a stage 

 of development close to hatching and has the pennaceous ju venal 

 plumage well developed, although still encased in sheaths like the 

 trichoptiles of cuculiform birds, it has no sign of an egg tooth. Inci- 

 dentally, it seems that the extent of prehatching development in 

 the megapodes is not generally appreciated. Whereas in most pre- 

 cocial birds, such as pheasants and ducks, the young are hatched 

 fully covered with natal down, in the megapodes this plumage stage 

 seems to be entirely telescoped into the period before hatching, and 



No. 2901.— Proceedings U. S. National Museum, Vol. 80, Art. I. 



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