Nature lovers, and especially those interested in wildlife, have an obligatory date in the Pyrenees in autumn: this is with the bellowing of the deer, which is a curious ceremony of sound that takes place in the idyllic settings of the Pyrenees and Pre-Pyrenees of Lleida. Areas such as the Alt Pirineu and Cadí-Moixeró natural parks, the Aigüestortes and Estany de Sant Maurici National Park, and especially the Boumort National Reserve, play host to this wonder of the animal kingdom between mid-September and mid-October. This is a period in which the males fight with each other to win the favour of the females, marking their territory, and bellowing constantly. It is a tremendous experience to discover, at first hand, how these animals behave as they seek to reproduce and ensure the continuity of their lineage amongst the females of the group: marking pine trees with their antlers, digging up the ground to leave their mark, fighting fiercely with clashing antlers, and staging these unusual concerts, which go on from dusk until well into the night. In this area, there are specialised companies and rural houses that organize guided trips to maximise the enjoyment of this experience and which enable visitors to observe this activity in all its splendour, while interfering as little as possible in what is a vital moment for this animal species.