By Charlotte Owen
Hidden among the tall grass, a young roe deer lies perfectly still. She is curled up small and her dappled coat blends with her leafy surroundings so effectively that she is almost invisible to potential predators. Not far away, her twin brother is tucked up in his own secret spot and there they will stay, silent and un-moving, until their mother returns to feed them. She is close by, browsing on brambles, grasses, herbs and low-hanging branches. She will select the freshest and most nutritious shoots from this bounty of lush spring vegetation to make sure she can produce plenty of high-calorie milk for her young, and it is safest for them to stay hidden while she grazes.
It is no accident that the timing of their birth coincides with such a rich leafy feast. Most roe deer fawns are born in late May and early June when spring has sprung, the weather is mild and food is plentiful. No surprises there - this gives them the best possible start in life and improves their odds of survival.
However the roe deer breeding season - or rut - takes place in the summer between July and August, and with a gestation period of around five months their fawns would be born some time in December if they started to develop straight away. This would be a bit of a disaster, so to solve this problem roe deer females exhibit a reproductive strategy known as seasonal delayed implantation. They mate in July, when they are in peak physical condition and at their most fertile, but the resulting embryos will not start to develop until December. This means the pregnant mothers can keep fattening up throughout the autumn to boost their own chances of surviving the winter, and their young will be born into the favourable conditions and relative safety of spring.It’s a successful strategy, usually resulting in twins and sometimes triplets.They will stay in their grassy hideaways for the first six weeks of their lives until they are strong enough to follow their mother into the forest, staying close by her side as they learn to forage for themselves.