The Mountain Ringlet is one of our most difficult species to see. It is only found in discrete colonies in remote locations, has an extremely-short flight period and can be very difficult to find in anything other than bright sunshine, since the adults tend to remain sheltered deep in grass tussocks in overcast and cool conditions. Given the right temperature this butterfly will take to the air as soon as the sun shines, bringing an apparently dormant landscape to life. As its name suggests, this butterfly is found in mountainous areas, typically at altitudes between 450 and 800 metres above sea level. The butterfly forms discrete colonies in particular areas of the mountains they inhabit and, on good sites, may be seen by the hundred.
This butterfly is found in two main regions in the British Isles. In England, it is found in the Lake District of Cumberland and Westmorland. It is also found in western central Scotland, primarily in the counties of Argyllshire, West Inverness-shire and Mid Perthshire with a few scattered colonies elsewhere. The butterfly is surprisingly absent from Snowdonia and the Pennines.
On the basis of four specimens in total, this butterfly is also thought to have occurred in Ireland, although this is questioned by Redway (1981). The last record is from 30th June 1918, as documented in Nash (1990). Ford (1945) attributes the small number of very dark Irish specimens to the subspecies aetherius [Esper (1805)], form nelamus [Boisduval (1840)], which is found elsewhere only at high altitude in the Alps. This form is less strongly marked than populations in Scotland and Cumbria and the orange band, found only on the forewings, is faint and contains no spots. The three Irish specimens with labels show that they were caught at Croagh Patrick in West Mayo (1854), Lough Gill in Sligo (1895) and Nephin in West Mayo (1897).
It is believed that this butterfly was one of the first to recolonise the British Isles after the last ice age. Despite this heritage, this species is a relatively-recent discovery, with the Lake District population being discovered in 1809 in Ambleside, Westmorland, and the Scottish population in 1844 in Perthshire.
Subspecies: Erebia epiphron epiphron
The nominate subspecies was first defined in Knoch (1783) as shown here (type locality: Harz Mountains, Germany). It is not found in the British Isles.
Subspecies: Erebia epiphron mnemon
This subspecies was first defined in Haworth (1812) as shown here (type locality: Red Screes, Cumbria, England). Haworth (1812) incorrectly states the type locality as Scotland. The British population is represented by this subspecies.
Erebia epiphron mnemon
alis supra nigro-fuscis, fascia postica communi annulari, annulis coccineis.Habitat in Scotia.Obs. Statura et magnitudo Pap. Pamphili. Alae anticae supra annulis quatuor, horum tertius dimidiatus et aliquantillum exterior. Posticae alae annulis tantum duabus, vis. secundus et quartus anticarum alarum. Subtus alae cupreo-fuscae, anticae punctis subtribus fere evanescentibus fuscis fulvo obscure circumcinctis, loco annulorum: posticae fere omnino impunctatae.In Museo Dom. Francillon, a captore Dom. Stoddart.TranslationWings blackish-brown above, the rear band on both wings ringed, with scarlet rings.Lives in Scotland.Obs. Size of Pap. Pamphilus. Forewings with four rings above, of which the third is diminished and slightly displaced outward. Hindwings with only two rings, corresponding to the second and fourth of the forewings. Wings coppery brown beneath, the forewings with about three almost vanishing dark points surrounded by ill-defined reddish yellow, in the place of rings: hindwings generally without spots at all.In the Museum Dom. Francillon, from the collector Dom. Stoddart.
This form was first defined in Cooke (1943) (type locality: Loch Rannoch, Perthshire, Scotland). This form is found in northern Scotland, north of a line between the Clyde Isles in the west and North Aberdeenshire in the east. It is found in most of the western isles and is also present in Orkney. Emmet (1990) and Riley (2007) elevate this form to subspecific status. This form differs from the nominate form as follows:
1. It has a larger wingspan (Cooke estimated 4mm on average).
2. The red spots are more conspicuous and more elongated.
3. The black dots inside some of the red spots are larger and more pronounced.
4. The underside of the forewings has a more conspicuous and better-defined red band.
Erebia epiphron mnemon f. scotica
Male. On the upperside of the fore wings of the Scottish race there is a series of six or seven broad elongated bright red spots, almost forming a band, though interrupted by the veins, rather as in the illustrations of subsp. mackeri on Plate 67 (figs. 754 and 756) of Warren’s Monograph of Erebia. In all but one of my 24 specimens this band extends below vein 2. In the Westmorland race the red spots are much less conspicuous and narrower (i.e. less elongated), and do not normally extend below vein 2. It is altogether a more insignificant and duller insect. The black dots inside some of the red spots are considerably larger and more pronounced in the Scottish race. I took one or two with broad elongated red spots entirely lacking in red dots. On the underside of the fore wings the uninterrupted red band is also more conspicuous and better defined in the Scottish race. It measures about 4 mm. in breadth, except for the dent at the centre of the inner edge.
There is one generation each year, with adults emerging at the start of June in the Lake District and early July in Scotland. The flight period is extremely short at any given site, in the order of a few weeks only.
The butterfly prefers moist or boggy ground in sheltered depressions where the foodplant, Mat-grass, is found in abundance. These are often found in small localised areas on a mountainside resulting in colonies that are highly concentrated.
When weather conditions are suitable, males can be seen patrolling back and forth low over the ground, in search of a mate. Any brown object is investigated in the hope of finding a virgin female. The female, on the other hand, is much more sedentary - typically waiting among the grasses for a male to find her. Courtship is brief and a virgin female is quickly mated. She continues to spend most of her time hidden away among the grasses, emerging only to lay or feed from whatever nectar sources are available. Males are also known to take in minerals from damp soil.
Eggs are laid singly on a blade of Mat-grass. They are pale cream when first laid, but develop brown blotches after a few days. This stage lasts 2 or 3 weeks depending on the weather. The egg is relatively-large compared with the size of the butterfly, with each female laying up to 70 eggs.
The larva eats its eggshell after hatching and selects the tenderest leaf tips on which to feed. As winter approaches, the 3rd instar larvae will crawl deep into grass tussocks where they hibernate. They emerge in the spring and recommence feeding. It is believed that some slow-developing larvae may spend two years in this stage, usually the result of a late spring and short summer.
This is one of the more difficult species to monitor given its remote habitats and is generally considered to be under-recorded. However, it is known to have declined at several low altitude sites, possibly as a result of global warming, and is therefore a priority species for conservation efforts.