The Pyrenean Desman is one of Europe's most unique and least known mammals. It is a small semi-aquatic insectivore with an elongated, mobile snout like a small proboscis, which it uses to explore the bottom of mountain streams for insect larvae.
It belongs to an extremely ancient group of mammals with very few living relatives worldwide. It is practically an evolutionary relic, surviving in the clean, well-oxygenated rivers of south-western European mountains.
Its presence is so difficult to detect that most people living beside its streams have never heard of it. This is despite its decline in recent decades being one of the fastest and most concerning among European mammals.
The Pyrenean Desman is a small mammal with a distinctive appearance. It has a long, slender, highly mobile snout ending in a small proboscis-like structure, tiny, barely visible eyes, and dense, dark brown, waterproof fur. Its long, laterally flattened tail is used as a rudder when swimming. It cannot be confused with any other mammal in its range due to its highly characteristic snout, which is unique among European mammals.
Small track, 2-2.5 cm, with five toes and partial webbing visible in soft substrate next to water. Tiny, elongated droppings, 0.5-1 cm long, containing remains of aquatic insect larvae, deposited on emergent stones along the bank as a territorial mark. Its presence is best revealed by the stones themselves, used as latrines and covered in small, dark droppings. The Pyrenean Desman itself is extremely difficult to observe due to its crepuscular and nocturnal habits and extreme discretion.
Mountain rivers and streams with clean, cold, well-oxygenated, fast-flowing water, generally between 300 and 2000 m altitude. Endemic to south-western Europe, with populations in the Iberian Peninsula and the Pyrenees, absent from the rest of the continent.
It feeds almost exclusively on aquatic insect larvae and other small invertebrates from the riverbed, which it locates primarily by touch and smell using its mobile snout during short, repeated dives.
Solitary and highly territorial, the Pyrenean Desman digs burrows in riverbanks with underwater entrances, defending a stretch of river against other individuals of its own species. It is mainly crepuscular and nocturnal, which makes its study and direct observation in the wild extremely difficult.
The Pyrenean Desman has experienced a very rapid and pronounced contraction of its distribution range over the last two decades. Documented declines exceed 50% in northern Portugal and 60% in the French Pyrenees. This has led to an aggravated threat status in recent assessments.
Construction of dams and hydroelectric power stations alters water flow and quality. Other threats are pollution of watercourses, competition and predation by the introduced American Mink, and climate change, which reduces the available flow in the mountain streams on which the Pyrenean Desman depends.
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