This species is widespread in the Palearctic realm, from Ireland in the west to Yakutia in the east, and to north-west China and Mongolia in the south. The marsh fritillary is in decline in Europe and it is one of eleven butterflies covered by the United Kingdom Biodiversity Action Plan. Within the British Isles, it is more frequent in the south and west, but especially in Wales where there is a stronghold This species lives in calcareous grassland, in woodland clearings, in damp marshy areas (hence the common name), and in heathy grassland, dominated by tussock forming grasses, including purple moor and rush pastures. In Finland, E. aurinia has been shown to favor semi-permanent grasslands and impermanent clearcuts in the forest. Young clearcuts were preferred over old clearcuts due to the dense growth of vegetation in old clearcut forests. In the United Kingdom, two types of grasslands can be inhabited by E. aurinia: damp grasslands that are either neutral or acidophilus and dry grasslands that have an abundance of plants growing in lime-rich soil (calcicolous grasslands). These butterflies can reach an elevation of 10–2,200 metres (33–7,218 ft) above sea level. In the British Isles, the marsh fritillary is usually found in damp, heathy grasslands that are called rhos pastures, from the Welsh word rhos meaning heath. Small populations can be an important element of the ecology because they produce many mobile individuals which can then found other populations. The marsh fritillary is protected under UK law, listed under Schedule 5 of the Wildlife and Countryside Act, and the EU Habitats and Species Directive (Annex II). The Devon Wildlife Trust owns a number of sites at which it monitors this species. Examples include Stowford Moor (near Holsworthy, Devon), Dunsdon nature reserve (near Bude), Mambury Moor (near Great Torrington), Vealand Farm nature reserve (near Holsworthy), and Volehouse Nature Reserve (near Holsworthy). In 2009, population counts had significantly increased from years 2007 and 2008. In 2018, a breeding population was found in Carmarthenshire, Wales, after an absence of 50 years. In Lithuania (included into the Lithuanian Red Data Book since 2000, red list category-3 (R))(Rašomavičius, 2007) is protected insect species. Euphydryas aurinia usually is found in natural and seminatural moist or wet oligotrophic grasslands (purple moorgrass and heath rush meadows), base rich fens, mostly in Eastern, North-Western and Central Lithuania, where its main foodplant Succisa pratensis (Dipsacaceae) is abundant. Inhabited patches frequently are situated along woodland edges or surrounded by bushes. Species is not found in Southern Lithuania where sandy soils predominate and in South-Western Lithuania where agriculture is very intensive.