Black Down and Sampford Commons is a 155.2 hectares (383.5 acre) biological Site of Special Scientific Interest in Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

 and Somerset

Somerset

The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...

, notified in 1952.
The Little Breach reserve, which forms part of the SSSI is an area of heathy grassland on Greensand, with some blackthorn

Blackthorn

Prunus spinosa is a species of Prunus native to Europe, western Asia, and locally in northwest Africa. It is also locally naturalised in New Zealand and eastern North America....

 and birch

Birch

Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...

, noted for its butterflies and moths

Moths

Moths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...

.

Blackdown and Sampford Commons have the finest and most extensive surviving examples of the heathland

Heath (habitat)

A heath or heathland is a dwarf-shrub habitat found on mainly low quality acidic soils, characterised by open, low growing woody vegetation, often dominated by plants of the Ericaceae. There are some clear differences between heath and moorland...

, carr woodland and marshy grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 habitats that have developed on the acidic soils overlying the Greensand and Keuper Marls of the Blackdown Hills

Blackdown Hills

The Blackdown Hills are a range of hills along the Somerset-Devon border in south-western England, which were designated an Area of Outstanding Natural Beauty in 1991....

. The heathland supports a typical invertebrate fauna

Fauna

Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

, including a wide variety of butterfly

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 species, and with spiders notably abundant. The site is regionally important for birds which favour heathland habitats.