From about mid-September until the end of October, the 'rutting' season takes place, when the herds split up and the mature stags try to collect a harem of hinds together. A stag of about five years old is in his prime at the start of the rut, with fully developed antlers, a thick neck with a heavy mane and plenty of fat reserves.
A stag will go to a peaty bog or muddy pool to wallow, covering its body with mud which helps to spread its strong rutting scent all over the body. Rutting stags also roar at each other - a deep bellowing sound - challenging each other. Two rival stags may sometimes walk slowly beside each other, a little apart, assessing each other's strength. The weaker one may walk away but if they seem to be evenly matched then they may begin to fight. They may clash their foreheads or just spar with their antlers. The stags may become injured during a fight but they rarely kill each other. On rare occasions the antlers of fighting stags become entangled so they cannot unlock them and they both starve to death.
The most successful stags manage to collect up to forty hinds in their harems and they spend most of their time endlessly patrolling a circle of ground around the hinds, chasing away any challengers, trying to prevent the hinds from straying and mating with each one as she becomes receptive. They hardly have any time to eat, and by the end of the rut, the stags are thin and exhausted.
The gestation period of the Red Deer is 225 - 270 days and the hind gives birth to a single calf (rarely two) in May to mid June. A hind about to give birth leaves her herd and finds a secluded spot, perhaps among bracken, to drop her calf. A young calf is brown with white spots and is well-camouflaged against a background of vegetation. It can get to its feet within a few minutes, can suckle ten minutes later and is able to run after a few hours. During the first few days of life, the calf is left hidden in the undergrowth when the hind is away feeding. After three or four weeks, the calf will follow the same routine as the adults. A calf is weaned at 8 - 10 months but stays with its mother until she gives birth again. Young stags stay with the hind herds until about three years of age.Read More: Antlers