Wildlife and habitats
The site is notable for a variety of species which are rare in a national, regional or local context. These include the dormouse, otter, pearl mussel (Margaritifera margaritifera), white-legged damselfly, and specialist beetles associated with river shingle, wetlands and high-quality dead-wood habitats. Kingfishers and sand martins can be spotted along the river. Among plant species, Devon whitebeam, wild service tree and bastard balm are of note. Also look out for bats including Noctules, Daubentons, Brown long-eared, lesser horseshoes, soprano and common pipistrelles.
Halsdon nature reserve covers an extensive area of flood plain pasture and valley-side woodland alongside a 2.6 km stretch of the River Torridge. The flood plain comprises improved, semi-improved and unimproved grassland, scrub and hedge banks. The valley-side is covered by semi-natural broadleaved woodland, with smaller areas of unimproved Culm grassland, acid grassland and improved pasture.
The reserve includes a long stretch of the River Torridge, representing one of the least disturbed stretches of this important Devon river system.
The site contains a wide diversity of habitats: old, neglected oak coppice and coppice-with-standards; younger plantation, secondary woodland and scrub; areas of unimproved, semi-improved and improved pasture, including areas of rush pasture and mire (Culm grassland); the dynamic river channel; and varying bank-side vegetation.
Seasonally flooded, semi-improved valley-bottom pasture is unusual in the region, as is the extent of natural erosion and deposition which is occurring along the river course. The Culm grassland communities are representative of a vegetation type which is typical of the area but now much fragmented and restricted to parts of Devon and Cornwall.