DPX'IDUOUS NATURE OF DEER ANTLERS 351 



natively, annual cycles of antler growth and reproduction in the ab- 

 sence of environmental stimuli could represent an atavistic reflec- 

 tion of temperate progenitors. Whatever the explanation, there is 

 reason to believe that when births are distributed throughout the 

 vear, the date at which a buck sheds his antlers may bear a regular 

 relation to the time when he happened to be born. Lvdekker 

 (1898), noting the persistence of irregular antler and reproductive 

 cycles among chitals (Cervus axis) living in England, reported that 

 when birth occurred in December, subsequent antler shedding usu- 

 ally took place each October. Similarly, a deer born in July sheds its 

 antlers in May or June. In the Philippine Rusa, Valera (1955) has 

 recorded that fawns begin to grow their first antlers at about one 

 vear of age, implying that subsequent shedding may occur a few 

 months before each succeeding birth anniversary. Unhappily, avail- 

 able data on these and other related phenomena among tropical 

 deer are fragmentarv and too often dependent on hearsay. Accurate 

 information on the life histories of deer native to equatorial regions 

 is, therefore, urgently needed if the relation of antler growth and 

 shedding to the reproductive cycle is to be more clearly understood. 

 Sufficient reliable evidence along these lines may provide clues as to 

 which endocrinological factors might best be subjected to experi- 

 mental investigations in attempts to determine how antler loss and 

 regeneration are induced. 



In view of the foregoing comparisons between deer inhabiting 

 different latitudes, it would be expected that antler growth cycles 

 (as well as other periodicities, e.g. molting, reproduction) would be 

 responsive to annual variations in day length and that the degree of 

 reaction might be proportional to the amplitude of these seasonal 

 fluctuations. In tropical regions, where diurnal alterations are mini- 

 mal, deer species tend to be verv irregular in the dates at which 

 their antlers are shed. That this is due to an inbred inability to re- 

 spond to day-length changes, and not to a lack of environmental 

 stimulation, has been demonstrated by the persistence of irregular 

 breeding and antler cvcles in such Indian deer as the chital and the 

 sambar after prolonged residence in England (Lydekker, 1898; Py- 

 craft, 1914; Bedford and Marshall, 1942). Unfortunately, I know of 

 no records of the reverse situation, namely, the transfer of temperate 



