Rhythms of reproduction,metabolism and coat growth in deer: a model for all non-domesticated seasonal ungulates?

Seasonally-breeding deer living in cool temperate environments exhibit pronounced seasonal rhythms of voluntary food intake, growth rate and fattening and the growth and development of the coat. All of these rhythms are considered to be entrained by photoperiod and melatonin, although so far this has only been demonstrated to be the case in one species, the red deer. This paper reviewed current data on seasonal rhythms in several species of deer. A comparison of two species with different breeding seasons, the red deer and the Pere David's deer, indicated that seasonal reproduction, appetite and coat growth rhythms are linked and may be controlled by a single circannual rhythm generator. All of these seasonal rhythms should be considered as adaptive for species living in cool temperate environments with marked fluctuations in food supply and climatic conditions.