Grazing with Red Deer

Pirbright Ranges, the UK's first deer park for habitat conservation?

Pirbright Ranges has restricted access which makes it challenging to manage the habitat with conventional techniques. SWT has worked with a group of partner organisations to introduce red deer on to the area to control invasive birch and pine whilst creating a mosaic of sward heights.

The herd size will be held at around 160 animals and as the population grows we are starting to see some of the desired impacts in reducing the growth of scrub and diversifying the structure of the lowland heath habitat. The stags are a key element to this as they damage larger trees with their antlers through fraying and thrashing the bark. We and our project partners are optimistic that as the population grows the positive benefits to the site will continue and increase.
Please note: Pirbright Ranges is a live firing range owned by the MoD. Public access is strictly prohibited.

Red Deer in the UK

From approximately 9000BC red deer were distributed across the whole of the UK and were the staple food of not only Mesolithic man but also wolves and bears, which were present in the wild until around 1500. After this time, a combination of hunting and the clearing of woodland for agriculture meant that red deer populations were reduced drastically. This was the situation until deer parks became fashionable in both the Norman and Victorian eras and releases into the wild alongside increasing woodland cover meant numbers climbed again. In Surrey, red deer are mostly restricted to parks such as Richmond although small herds are now reported in the wild in some parts of the county.

Deer Physiology

Deer physiology has adapted to cope with high levels of mortality and predation as well as the changing availability and quality of food. Hind calves are able to become pregnant in their first year if they reach a minimum body weight, and calving success rates in adult hinds can be 85% or above. The 8.5 month (234 day) pregnancy is timed perfectly with the flush of spring growth in late May, supplying much needed energy for the new mothers. In fact, a hind requires up to 40% of her annual energy in just the three months after she has given birth. Red deer hinds usually give birth to a single calf every year with twins being extremely rare.

The period from late summer to December is critical for red deer as they need to gain sufficient reserves to enable them to survive until the spring. Although deer continue to graze through the winter, time spent grazing and moving is much reduced to conserve energy. In addition, deer go through a period of reduced appetite in winter and lower their average heart rate (from 65 to 40 beats per minute) which subsequently reduces their metabolic rate and conserves body fat. This is reversed in the spring when food is plentiful and their digestion reverts to processing a greater amount of grazed plant material than body fat.

Deer are not well insulated and being exposed to periods of cold, wet weather will heavily increase the drain on their winter reserves, therefore having shelter in the form of woodlands, hillsides and deep heather or bracken is essential if they are to survive.


The antlers on the males are made from bone and regrow every year from a point at the base of the head called the pedicle. Every year, around April, the lengthening days trigger a hormone level change in the stags which causes calcium to be reabsorbed at the base of the antler, eventually weakening it to the point it breaks off. Deer have blood that has exceptional coagulating properties so the wound quickly heals and the new antlers grow immediately.

Whilst the new bone is growing, the antlers are covered with a soft fur which supplies the blood vessel for the bone (known as being ‘in velvet’) with growth rates reaching an astonishing one inch per day. Around late August another change in hormones causes the blood supply to the new antlers to be cut off and for the bone to harden, the stag then scratches the now itchy velvet off the antlers by rubbing against trees.

Hinds & The Rut

For the stags, the objective of the rut is to hold onto a large group of hinds until they have all come into season. To do this the stag has two options: to defend them from rivals, firstly to impress the challenger with his body, antler size and his roar and secondly is to fight.

The antlers are designed to lock together to reduce the chance of serious injury and fights are won through a combination of body size, aggression and technique.