A deep, resonant sound echoes through the forests of France each evening until mid-October. This is the bellow of the red deer, the only large deer species in French forests that makes this sound during the mating season. Known as the rut, the mating and reproduction period for red deer occurs once a year, from mid-September to mid-October. As temperatures drop and daylight hours decrease, male deer experience a surge in testosterone, which triggers the bellow. This call can be heard several kilometers away and serves to impress rivals and attract females. During the three to four weeks of the rut, a male red deer eats very little, focusing its energy on defending its territory, bellowing, and keeping a group of female deer, or does, under its protection. To establish dominance, a male red deer may roll in the mud, tangle grass in its antlers, and mark its territory with urine. However, the bellow alone is not always enough to secure a mate. A large male weighing 200 kilograms can lose up to 40 kilograms during the rut, which is about one-fifth of its body weight. Observations suggest that males can lose between 10 to 20% of their body weight during this time. The bellowing period is crucial for attracting females and intimidating rival males, though it can sometimes escalate into physical confrontations. When vocal displays fail, red deer may fight using their antlers, with some fights becoming so intense that they can lead to exhaustion or even death. Occasionally, two males become locked together with their antlers entangled and die from exhaustion. These violent encounters are rare, though. The rut is a high-stakes time for male red deer because females are only sexually receptive for one day a year and give birth to a single fawn. This means males have a very limited window to pass on their genes, contributing to the intensity of the mating ritual. The gestation period lasts around 225 to 245 days, with fawns typically born between May 15 and June 15. Outside of the rut, males and females live separately. In the Massif Central region, the Monts du Cantal provide an ideal location to observe the bellowing. Their vast forests and high-altitude pastures echo with the calls of red deer every autumn. In France, the hunting of deer species, including red deer, is tightly controlled by the environmental code. Since 1963, a mandatory hunting plan has been required to ensure sustainable practices. Hunters must exercise caution, especially around rutting males, injured, or cornered animals. The best times to hear the bellow are during the cool, quiet evenings at sunset or sunrise. Observers are advised to remain still, wear warm and quiet clothing, and avoid using flashlights. The experience often involves waiting for several hours in the dark. In areas where red deer are fed regularly, they quickly regain their weight after the rut, but in the wild, they must endure the scarcity of food during winter.