MOUNTAIN RINGLET IN CUMBRIA
you are walking in the Lake District in June or early
July please look carefully and report any sightings
via "Contact Details" above. Please include
a grid reference and number seen if possible.
Mountain Ringlet Erebia epiphron is a speciality
of the Lake District, this being the only place in England
and Wales where it occurs. It is an enigmatic species,
living on the high fells but only flying in sunshine!
Its larval foodplant, Mat Grass, is everywhere,
but the butterfly is found only in specific areas, apparently
linked to the geology, soil type and possibly aspect.
believe everything you read in butterfly books about this
species; this webpage is based on local knowledge and
the efforts of members of Butterfly Conservation's Cumbria
branch, who monitor the fells. One esteemed text, recently
re-issued, quotes "evidence" that, because of
global warming, a third of colonies have become extinct
and on average other colonies have moved 140 metres higher
up the fells. Apart from the fact that this would mean
that most colonies were now on the very summits, which
are usually avoided, there is actually no evidence, based
on observation, that the species is in anyway declining
in Cumbria. In fact, survey results from 2010 onwards
are very healthy, but that may only mean that a lot of
effort was expended searching for this difficult species
and the weather was reasonably favourable.
research quoted above was apparently based on surveys
of sites in the last three weeks of July, as that is when
the books say the species usually flies. In Scotland perhaps,
but in Cumbria you will only find the tail-end stragglers
by then (see below). Furthermore, the weather is crucial
when conducting surveys. Two visits in 2010 to the same
site, two days apart, yielded counts of 200+ and 5, the
former when it was sunny the latter when largely cloudy!
On one day you might conclude from casual surveys that
the species was thriving, on the other that it was in
is no doubt that the species does spread out during the
flight period in good or even most years, which is why
records of ones and two's are of little value in monitoring
its distribution. But we are now fairly sure that breeding
sites do move and absolutely certain that it breeds as
low as 200 metres (650 feet).
sites show a marked preference for the west and south-west
of the region, especially around Wasdale, the Langdales
and Honister where numbers have traditionally been highest
and are holding up well. Colonies to the east, around
Helvellyn, Haweswater and Kirkstone, are fewer in number
and more isolated, although some are very strong. The
Red Screes site, where the species was first discovered
in Britain in the early 1800's, now appears to be weak,
but new breeding sites have been found close by, one as
recently as 2010. The species does appear to move about
(sometimes downhill!), for reasons we don't yet understand.
This is another reason why it is difficult to assess population
changes; one site may become extinct but there may be
two new ones nearby in some less accessible place that
we don't know about!
Mountain Ringlets may be found in the Lakes between the beginning
of June and mid-July, but at one low level site emergence sometimes
occurs before the end of May! However, numbers peak for most
colonies around the last two weeks of June, followed by a fairly
long tail when only small numbers tend to be found. Analysis
of breeding records (i.e. sites where significant numbers have
been recorded) over the last ten years gives a distribution:
is a frustrating species for the casual observer to plan to
see and why records over the years are relatively sparse, despite
the increasing popularity of fell-walking! If you want to see
the species, I'd suggest you pick the day in the last fortnight
of June that has the best weather forecast promising long periods
of sunshine with temperatures above 15 C at 500 metres!!! However,
be warned, a cold spring, as in 2015, can delay emergence by
two or more weeks. Try Hartsop Dodd, Kidsty Pike, Raise, Cold
Pike/Little Stand, Brandreth or the Irton Fell/Illgill Head
ridge rather than sites suggested in the books.
sites are normally found between 550 metres and 700 metres (to
set that in context, the very highest peaks in Cumbria are just
over 900 metres). However, we know they can thrive at 200m just
as well as at 650m if the conditions are right – we
just don’t know what those conditions are yet!
spite of its preference for altitude the species does avoid
the summit tops, as it is nearly always found in sheltered
spots or flushes at the base of crags. Mat Grass,
its larval food plant, occurs in every 2 km square of the
Lakes. BUT there have been no records ever
from some fells (although well walked) such as Great Gable,
Bowfell and the Band, The Fairfield Horseshoe, and Skiddaw,
despite the abundance of Mat Grass throughout. The species
is very strong just to the north of the Wrynose Pass, but
curiously has never crossed the road to the Coniston range!
research on Scottish Mountain Ringlets have shown the species
prefers herb-rich Nardus grassland. The herbs on which
the Mountain Ringlet nectars, such as Thyme, Tormentil and Meadow
Buttercup, tend to be found at the base of crags and gullies,
where mineral enrichment occurs (see photo above at Whin Rigg
- photo courtesy of Steve Clarke). They are virtually absent
on the summit tops, making this another reason why the species
is unlikely to move higher in the Lakes. Perplexingly however,
one site (High Raise) that regularly returns good counts, including
1600 in 2011, has virtually none of the above flower species
and only tiny amounts of Heath Bedstraw. What was significant
about this site is that the height of the vegetation was higher
than that measured at all other sites surveyed.
appears to be a very strong geological link to its habitat requirements
(see map below). Known sites are found only on certain of the
igneous Borrowdale Volcanic rocks - the Skiddaw and Silurian
Slates to the north and south respectively have no colonies.
It may be that the areas avoided, being more acidic, are mineral
deficient (especially in calcium). Mat Grass is so
lacking in mineral nutrition that even the sheep leave it alone
(which is why it becomes dominant if the fells are over-grazed).
It is known that small areas within the Volcanic rocks are base
rich. David Clarke reports (2010 Carlisle Naturalist 18.2) finding
the lichens Solorina saccata and Peltigera leucophobia
and the spleenwort Asplenium viride in a gill-ravine
near Thirlmere. These are all calcicoles; perhaps species of
this type may be indicators of Mountain Ringlet habitat.
Known breeding sites for
Mountain Ringlet grouped together by colonies within loose
geographical boundaries determined by valleys and ridges.
The western colonies could be regarded as one super-colony.
The light and dark pink backgrounds are areas of igneous
rock. Of the areas not used by Mountain Ringlet, the lilac
background is Skiddaw slate, red is granite and brown
to the south Silurian slate.
I have grouped the known breeding sites into colonies that have
some degree of geographical separation, as there is really no
strong evidence that these breeding sites should be treated
as separate colonies in the conventional sense i.e. are separated
by intervening habitats that are unsuitable. Thus, all
the sites along the Irton Fell to Illgill Head ridge form a
"Wasdale" colony, the High Raise and Kidsty Pike sites
form a "Haweswater" colony etc.
the colonies in the west of the Lake District could all be considered
to be one super-colony as they are all inter-connected by the
ridges that radiate out from the central dome of the Scafells.
Any interchange that does occur here will enable genetic mixing
and strengthen future generations. It may be the case that colonies
in the east have a different genetic make up and, being more
isolated, could decline through lack of genetic mixing. On the
other hand it may be the case that this area is under-recorded
and there may be more inter-linking sites than we know about
a colony there are genetic differences of size, brightness and
number of spots. English specimens differ slightly from those
of Scotland, which differ again from European specimens.
has been much speculation about the potential loss of an alpine
species like the Mountain Ringlet as global warming occurs.
It is just speculation, as so little is known about the habitat
requirements and ecology of this species. The site that always
features the earliest emergence (Irton Fell) is the one found
at lowest altitude (200-250m) and is on the milder west coast,
where it enjoys the benefits of warm Gulf Steam air and higher
humidity - just the sort of conditions Global warming is supposed
to bring. This colony has been observed for over 60 years, with
little apparent change in strength, even in recent years.
the other hand, despite global warming, we had two of the hardest
winters for years in 2009-10 and 2010-11. Snow covered the fells
continuously for five months and numbers of Mountain Ringlets
recorded in 2010 and 2011 did seem to be good; 1600 were recorded
on one day across four 10 km squares at High Raise in 2011.
But this may only be the result of more determined monitoring.
Flight times were not noticeably different in 2010 and 2011,
perhaps because the early months enjoyed dry sunny weather just
at the time larvae were developing and pupating. Could it be
that the amount of snow cover is important? At low altitudes
this protective cover is not present and appears not to be needed.
At high altitude it may be beneficial, in which case the species
may well benefit from moving to higher ground in Scotland, but
this is not possible in the Lake District. It's such a complex
picture. To throw another spanner in the works, many pupae are
devoured by Field Voles, a species notorious for rapid fluctautions
in numbers from year to year even without hard winters!
effects of global warming will manifest themselves in changes
in the habitat, but we need to understand the precise habitat
requirements of this species before we can assess what changes
are taking place! Butterfly Conservation Cumbria branch is working
hard to try to understand those requirements.
in all, the Lake District Mountain Ringlets are a fascinating
and unsolved enigma! If you have any comments on the above theories
please get in touch.