This is when the males, known as Stags (Red deer) or Bucks (Fallow deer), compete for dominance of the herd and the right to mate with as many females, known as Hinds (Red) or Does (Fallow), as they can. Fuelled by testosterone, the males give out a guttural roar, called bolving. This is to attract females and to warn off other males. If another male won't back down, the two will parallel walk and size each other up. They will then lock antlers and push against each other, to see who is the strongest. This can go on for sometime until one admits defeat and backs down. Injuries are common and sometimes fatalities occur.

The victor will sniff and lick the air picking up the females scent and then knows which females are receptive to mating. He can mate with upwards of thirty females!

The baby deer, known as Calves (Red) or Fawns (Fallow), are born in May/June when mum goes away from the herd and gives birth in long grass. This provides some protection from predators and the mother returns several times to suckle her newborn. Eventually, when weaned, the youngster rejoins the herd and stays with them.

It is only males that grow antlers, in the first year they don't grow any, in the second year two pointy uprights grow, the young deer are known as pricketts and in their third year spurs grow as they take on adulthood. Then in spring they fall off, this is called casting. Immediately they start growing a new pair, thick membrane called velvet covers the antlers. Towards the end of August the velvet becomes itchy and starts to peel off. Very often it resembles an old sock hanging loose, the bone underneath then hardens in preparation for the rut.

Deer footprints are v-shaped and are called slots, the wider the v the bigger the deer.

After the rut is over it is not uncommon for the males to have lost a third of their bodyweight, building up prior to the rut to arrive in peak condition.