web banner test mergebw


Seasonality in deer is regulated by daylength, technically known as 'photoperiod'. Photoperiod is the relative amount of light to dark (day to night) in a 24-hour period. The photoperiod observed for a particular place is not constant during the year, but the pattern of change over the year is constant.

Key points

Deer synchronise their annual patterns of reproduction, growth, coat moult, antler growth and other aspects of physiology to photoperiod.

Calf survival is optimised if calving occurs during the most clement weather.

The animal perceives changes in the daylight:nightime ratio through its eyes, via the optic nerve to the brain.

Why does photoperiod change?
What are the effects?
How do deer respond to changes in photoperiod?
What is the effect of photoperiod on breeding?
Why is photoperiod important in deer breeding?
Can we control photoperiod?

More resources

Fennessy, P.F., Suttie, J.M., Fisher, M.W., Jopson, N.B., Webster, J.R. (1990) Melatonin in male deer-effects on seasonal growth. Proceedings of a Deer Course for Veterinarians. Deer Branch NZVA 7: 159-166.

Webster, J.R., Corson, I.D., Littlejohn, R.P., Stuart, S.K., Suttie, J.M. (1998) Photoperiodic requirements for rapid growth in young male red deer. Animal Science 67: 363-370.

Back to Breeding