Newborn and weanling fawns were held under reversed annual light cycles to learn if the subsequent replacement of their antlers would coincide with the anniversary of their births, as occurs in nature, or adapt to the artificial seasons of increasing day lengths even when these fall at the "wrong" time of year. The first sets of antlers developed at approximately the normal age when the deer were yearlings. These antlers, however, were shed and replaced half a year earlier than would otherwise have occurred under natural environmental conditions. It is concluded that the onset of renewed antler growth is not a response to every other time the photoperiod increases or decreases, but is triggered by lengthening days, irrespective of the age of the deer.
Age Factors Animals