The lives of red deer are dictated by the seasons. Throughout winter and spring, males live in loosely structured bachelor groups, away from females, who generally associate with their maternal female relatives. This separation of the sexes ends as the autumn rut (or breeding season) approaches and males move into the areas of good grazing where females are usually found. During the rut, which runs from mid-September to mid-November, males compete with each other through roaring contests and fights to control harems of females, and mate with females as they come into oestrus. Only a few males – generally those with the best antlers and fighting skills – succeed. In doing so these top males expend an enormous amount of energy: they eat rarely if at all, roaring day and night whilst having to fight or chase off challengers and herd in females. As the top males become exhausted, they move away from the rutting areas, reforming their bachelor herds. Sometimes this allows younger males a chance to mate with females coming into oestrus late in the rut. Females may not be entirely passive during the rut; although they mostly feed in their normal groups, when they come into oestrus, they are sometimes observed in a different harem, and may mate with the new male. By the end of the rut, many, but not all, mature females (aged 3 or more) will be pregnant, with a single calf.
The winter months that follow are tough times for red deer. Males must recover body condition lost during the rut and females that have conceived must support both themselves and their growing foetus through the winter. Most natural deaths occur in late winter (February to April). The youngest and oldest deer are the most likely to succumb to the lack of food and harsh weather as are males which fail to recover condition from the rut, particularly in wet and windy colder years. As spring approaches, weather conditions improve and the grass begins to grow again. Many deer calves will die in their first or second winter of life: only 45% of male calves and 50% of female calves will make it to their second birthday. For those that survive the riskier juvenile period, the average natural lifespan of a female is just over 10 years and of a male is just less than 9 years.
In March-May there is a final spurt of foetal growth before females give birth to their calves, in late May and June. For the first few weeks of life, the spotted new-born calves remain hidden when not being suckled by their mothers. After this, they will follow their mothers closely and continue to take milk until at least the beginning of the rut. If the mother fails to conceive during the autumn rut, the mother may continue to suckle the calf well into the following year.
Males grow a new set of antlers each year. They cast the previous year’s antlers in March and April, and during spring and summer, re-grow a new set whilst also re-building their strength in preparation for the cycle beginning again in the rut. Older males grow larger antlers with more branches than younger ones, and also start the process earlier in the year. When antlers grow, they are covered in a fine layer of ‘velvet’. This is ‘cleaned’ in August/September, and males are then ready to rut in the autumn.
Photo credits: Martyn Baker