Male red deer grow new antlers every single year. In spring, two soft bumps push up from the top of the stag's head. Through summer they grow and grow, covered in a fuzzy skin called 'velvet'. By autumn they are full-size, the velvet rubs off, and the antlers are hard and pointed - sometimes a metre across.
In autumn, stags use their antlers to challenge each other for the right to lead a group of female deer (called hinds). They throw their heads back and let out a deep roar that echoes for kilometres through the forest. This is called the 'rut'. People in Denmark walk into the forests just to hear it.
After winter, the antlers fall off. The whole thing happens again the next year - the antlers always grow back bigger. By the time a stag is fully grown, his antlers might have 12 or more points (called 'tines').
Female red deer have no antlers, but they are the family bosses. They live in small groups with their calves, and they raise the young together. A red deer calf is born in spring with pale spots all over its coat - perfect for hiding in the dappled sunshine of the forest floor.