On 1 April 2024 on a sunbaked hillside east of Qala village in Gozo, I enjoyed Swallowtails, Red Admirals, Painted Ladies, Clouded Yellows, Long-tailed Blues and Wall Browns. The temperature exceeded 31 Celsius that afternoon, the highest ever recorded in Malta during April. The airborne Swallowtail is eye-catching, blending silk with steel as it manoeuvres intense hilltop gusts. On ethereal high ground, this elusive butterfly evanesces beyond and within view, the ubiquitous cream Coraline limestone absorbing it only for it to condense to a just perceptible presence on a buff senescent sprig, typically African Carline Thistle, a relic of last summer’s moisture-starved ground. The Swallowtail’s command of the air in these windswept hills is soul-gripping, its beauty refreshing in the harshness of heat and naked rock.
Malta in spring sees no shivering in the rain and dank wind or peering at a murky sky for a hint of direct sunlight, a staple for early spring butterflies in Ireland. Ireland’s butterflies did not get much encouragement from the March and early April weather. Wet spring weather inhibits butterflies. March was wet so its above-average temperatures were unavailing. April 2024 shows no signs of being suitable but three weeks lie ahead.
I noted some positives this year. In his impressive book on British and Irish butterflies, Peter Eeles states that the Speckled Wood caterpillar can overwinter only in the third instar (instars are inter-moult stages in the caterpillar) with other instars dying with the onset of extreme cold. However, the fourth instar caterpillars I reared outdoors in County Meath survived the prolonged low temperatures during January 2024. Our Speckled Woods are tailor-made for the Irish winter.
Regarding winter survival strategies our butterflies occupy three categories: the species that migrate south, species that overwinter as adult butterflies and those that pass the colder months in juvenile stages (egg, caterpillar, chrysalis). Four hibernate as adults: Brimstone, Small Tortoiseshell, Peacock and Comma, and these have been seen this spring. They return to rest when spring weather reverts to winter. These species are long-lived as adults and can play a longer game.
For the rest of our resident butterflies, carpe diem applies. Ireland’s spring butterflies are particularly adept at exploiting brief good weather to transact their life’s work. On 3 April Lisa Scarff saw her first butterflies of the year on the Sheep’s Head peninsula in West Cork: a Holly Blue and three Green Hairstreaks. Green-veined whites were reported on 31 March (Lullymore, Kildare) and 5 April (Marlay Park, Dublin). A Large White was seen on 31 March (Sutton, Dublin). The increasing day length added to milder temperatures tempted these out of their pupae. These emerge over several weeks, spreading the risk, so that some will appear at the right time.
Another early spring butterfly, the Speckled Wood (unique in its ability to overwinter as a pupa or larva), is awaited. In 2023, the first Speckled Wood reported to Butterfly Conservation Ireland appeared on 30 March. Most of our spring butterflies are yet to emerge: Dingy Skipper, Cryptic Wood White, Small White, Orange-tip, Small Copper, and Wall Brown. As connoisseurs of butterfly beauty, you will be impatient to savour these delights. Of some delights, the delay makes the taste sweeter. Enjoy your butterfly recording in 2024: the weather will turn!
Records can be emailed to us at: conservation.butterfly@gmail.com
The information needed for a valid record is described at
British Swallowtail reared specimen. Photo copyright Peter Eeles. Source: www.ukbutterflies.co.uk
When I was eight, my father bought me a book, A colour guide to familiar Butterflies, Caterpillars and Chrysalides by Josef Moucha, beautifully illustrated by Bohumil Vančura. There was not much money in our home, so I was surprised as well as delighted with the book. Many happy hours were passed drawing and painting butterflies from the book. The first butterfly illustrated is the Swallowtail Papilio machaon. The illustrations show the butterfly with wings extended, the pupa affixed to a dead stem and the feeding caterpillar, perched high on a foodplant. The plant is an unnamed umbellifer (celery, carrot and parsley family).
The Swallowtail is a large, beautiful species, well distributed in Europe. It also occurs in North Africa, temperate areas of Asia and parts of North America. It also occurs on Mediterranean islands, including small islands like Gozo (Malta). Last year, the Swallowtail on Lampedusa Island in the Mediterranean was identified as a new subspecies, not of the Common Swallowtail Papilio machaon but of the Desert Swallowtail Papilio saharae. The adult Desert Swallowtail looks identical to the Common Swallowtail when seen in the field. The study that makes this claim examines all life stages and is a morphometric study (looking at the size, shape, colour etc of individuals). It did not use genetic techniques.
I have read the study carefully, and while the butterflies on Lampedusa have characteristics referable to the Desert Swallowtail, they also share traits with the Common Swallowtail. For example, the adult Desert Swallowtail has 30-31 antennal segments, while the adult Common Swallowtail has 33-36 antennal segments. Most of the Lampedusa specimens had 30-31 segments but some had 33 and one had 35.
The authors note “that the population on the island of Lampedusa possesses morphological traits of both P. saharae and P. machaon, plausibly the result of a hybrid swarm…” Intriguingly, the authors state: “The Lampedusa taxon appears to be, quite literally, a species in the making through the process of natural hybridization. Papilio saharae and P. machaon are known to hybridise naturally in Israel, where the two species maintain a contemporary sympatric association (both species occur together in the same area), contrary to the case of the Lampedusa taxon (a taxon is a biological entity of any status), which has been isolated for millennia.”
The authors made the decision, based on their morphometric analysis of all our four life stages, to recognise the swallowtail found in Lampedusa as a ‘new’ subspecies of the Desert Swallowtail, proposing the name Papilio saharae aferpilaggi ssp. nov (ssp. nov. means new subspecies; the subspecies name refers to the fact that the taxon originated in Africa, hence, the use of the adjective âfer which implies “of Africa”, while pilaggi is derived from the Sicilian name of the island group, Ìsuli Pilaggî.’)
One of the features that I did find persuasive for anchoring the swallowtail found on Lampedusa to Papilio saharae is that some of the pupae the researchers reared did not hatch but entered diapause (a delayed development used to deal with unsuitable conditions, such as extreme heat). The Desert Swallowtail pupa is known to enter diapause, sometimes taking over a year to hatch. The swallowtail in Malta, Sicily and southern Italy do not habitually resort to diapause, at least in the long term.
Swallowtail (Maltese Islands). Photo J. Harding.
The swallowtail has much to teach us about how it varies across its wide range. Over 50 subspecies of Papilio machaon have been described so far, and if genetic analysis is used, some might be regarded as full species. Some might have arisen from hybridisation, geographical isolation and ecological conditions, such as climatic and habitat conditions.
One such subspecies is the British race of the Common Swallowtail, Papilio machon britannicus. It differs in appearance from the main European Common Swallowtail, Papilio machaon gorganus and it is also restricted to one habitat type and one larval foodplant. It occurs only in fens, and breeds on Milk Parsley Peucedanum palustre. In Europe, the species breeds on a range of plants, especially Fennel Foeniculum vulgare, Wild Carrot Daucus carota, Fringed Rue Ruta chalepensis, etc.
The British Swallowtail used to occur widely in the extensive fenlands in central and eastern England, but it disappeared from all but a few places near the Norfolk coast when the vast fens were drained for agriculture. Thus, the fens of Cambridgeshire are now featureless flat farmland. Its last site in Cambridgeshire was Wicken Fen, but it was lost from the fen in the early 1950s when it became too dry and probably overgrown to support the foodplant in the correct circumstances for the butterfly to use it.
The Norfolk fenlands are a big destination for butterfly lovers in England. Seeing Britain’s rarest and largest native butterfly is a big tick on one’s list. It is a powerful flyer, with a dramatic surging flight and an especially dramatic courtship flight when both sexes fly vertically into the sky until almost out of sight before descending to the ground to mate.
As you might have guessed by now, the butterfly is in grave danger. According to The Guardian, only 81 swallowtails were counted in Norfolk last summer (2023). It might be the world’s rarest butterfly. Even worse might be unfolding. The fens are wetlands, with water typically near or at times above the surface of the ground. The chrysalis is formed low down on reeds and has been known to survive short periods of inundation. However, many East Anglian fens have been flooded since last October.
In Norfolk, the butterfly usually starts to emerge in May. Will any emerge this year? Is it about to become extinct? The situation is, to quote noted English Lepidopterist Peter Eeles, ‘absolutely shocking.’ I contacted Peter to check whether the recent report in The Guardian reflects the true situation, or whether the low number recorded last summer indicates low monitoring effort. Peter confirmed that the monitoring is of a high standard; in other words, the population is in crisis.
It is not simply that the population abundance has fallen. The distribution of the population has declined too. Between 1976 and 2019 its distribution change is -27%. This means that the butterfly has lost habitat at the rate of -12% per decade. Loss of area occupied is very serious because its shrinking distribution leaves it more vulnerable to changes in the areas it still occupies, such as the flooding since October 2023.
Bad news arises from more than one cause. The rising sea level off the Norfolk coast is increasing salinity (saltiness) in the fens; the Milk Parsley the British Swallowtail relies on needs fresh water. Salinity affects plant growth and germination. In summer droughts there is not enough water falling as rain to keep salt water out.
Milk Parsley is not the only rare plant in the fens; Fen Violet, for example, occurs there too. Some efforts to protect Milk Parsley harm other rare plants, so a conflict of priorities, common in small areas devoted to nature, is a further conservation conundrum.
Bizarrely the Red List of British Butterflies 2019 assesses the Swallowtail as ‘Vulnerable,’ not as ‘Endangered’ or ‘Critically Endangered’. In this instance, the criteria used appear to be unfit for purpose.
It is worth noting that the International Union for the Conservation of Nature (IUCN) Red Listing process is complex and statistically prescriptive. Some key points to bear in mind are that it is an assessment of extinction risk and not conservation priority, that rarity alone is not sufficient for Red List qualification and that historical declines that have ceased are not relevant. Therefore an animal that was once very widely distributed and which lost the vast majority of its distribution and population would not be ranked as under threat today if its distribution and population were stable as recently as the decade before the list was drawn up or reassessed. One wonders when considering a numerically small population confined to a small area of at-risk habitat if another criterion/criteria can be applied to assess its status.
British Swallowtail underside. Reared specimen. Photo copyright Peter Eeles, Source: www.ukbutterflies.co.uk
My instinct apart from decrying the widescale loss of fens inland would be to embark on an ambitious landscape-scale re-wetting programme to recreate suitable habitat inland to save Britain’s most iconic butterfly. Captive breeding, if not already in place (captive breeding was carried out in Monk’s Wood in the past) must be instituted immediately and maintained until the habitat is available.
Being restricted to small patches of habitat is disastrous when things go wrong. Landscapes must be protected, not sites. In this country, we cannot say we haven’t been warned.
There are hundreds of museum specimens of the British Swallowtail. Soon, that’s likely where you’ll need to go to see it.
References
Cassar, Louis-F, Catania, Aldo (2023): A new subspecies of Papilio saharae Oberthür, 1879 (Lepidoptera: Papilionidae) from Lampedusa, Italy.
Fox R, Dennis EB, Purdy KM, Middlebrook I, Roy DB, Noble DG, Botham MS & Bourn NAD (2023) The State of the UK’s Butterflies 2022.Butterfly Conservation, Wareham, UK.
Biodiversity Ireland Issue 2 Autumn/Winter 2023 has been published by the National Biodiversity Data Centre. Among other interesting biodiversity topics, it reports on trends in Ireland’s butterflies, giving interesting information about abundance trends in 2022 plotted against 2008, the baseline year for recording butterflies in Ireland using transects and phenology or specifically in this case, the timing of butterfly flight periods.
Just a quick reminder about what butterfly transect walking involves. In Ireland, the main flight period lasts from April to September. Accordingly, a fixed route likely to contain butterflies is walked once a week from 1 April to 30 September, and the number of each butterfly species is recorded. The data is sent to the National Biodiversity Data Centre where it is added to their database and analysed for abundance and phenology trends.
It is interesting to walk a transect, not just for the pleasure it brings but to see how nature changes through the seasons and between years. However, sometimes the findings are more interesting than we would like them to be. The National Biodiversity Data Centre has found that there was an overall decline of -57% in the number of butterflies flying in 2022 compared to 2008. This information reflects the flight data of the 15 most common butterflies. Just a reminder that 2022 was one of the warmest years globally, and Ireland had hot weather in July and August when many of our butterflies are at their flight peaks so we might have expected higher numbers. I recall being in the Burren in early August 2022, in beautiful habitats and being underwhelmed by the number and range of butterflies on show. Here is my record for 6 August 2022:
Small Copper 3, Common Blue 2, Brown Hairstreak 5 (female 1), Speckled Wood c.6, Grayling 3, Meadow Brown 28, Ringlet 2, Small Heath 2 between R 30322 94432 and R 29846 94242, Knockaunroe, Co. Clare. Sunny, breezy, c.17C.
Note the absence of Wood White, Brimstone, Small Tortoiseshell, Peacock, and Silver-washed Fritillary, among others, from the records. It is possible that the warmth of July 2022 brought an early close to the flight period of Wood White, Brimstone, Peacock and Silver-washed Fritillary. However, to see not one of any of these species is strange, especially as all these butterflies (apart from Wood White) were being recorded elsewhere in Ireland at that time.
Caher Valley Loop Walk, County Clare, August 2022
Regarding individual butterfly species, 12 of the 15 showed declines since 2012, two (Brimstone and Holly Blue) showed stable trends, while one, the Peacock, showed an increase. Numbers of some grass-feeding species, such as Speckled Wood, Meadow Brown and Ringlet show dramatic falls since 2008. Cryptic Wood White, Orange-tip, and the three common whites show big declines too. The decline in the numbers of common butterflies is worrying because these are mobile, have a range of caterpillar foodplants or one or two very common foodplants and are not confined to habitats that are restricted in Ireland, like limestone pavement or ancient woodland. Such declines suggest that the general environment is becoming less hospitable to wildlife generally.
What about the less common butterflies? There is less data for these, but the data suggests that Dark Green Fritillary, Wall Brown and Grayling have a slight downward trend, while Dingy Skipper looks stable. The report does not provide data for the other less common butterflies, like Pearl-bordered Fritillary, Marsh Fritillary or any of the hairstreaks.
A Burren Grayling resting on a rock. The species is abundant here during August.
The 2022 season shows that the peak of the flight periods occurred two weeks earlier than the peak seen in 2021. The increased heat in 2022 is likely responsible for this difference. While some butterfly species (Speckled Wood, Meadow Brown and Small Heath are examples ) will emerge over a lengthy period, spreading the risk of emerging in bad weather over several weeks and even months, prolonged warmth and high levels of direct sunshine may result in larvae of some species developing faster and more reaching maturity together, culminating in a mass emergence over a shorter time.
The Meadow Brown was once described as “a butterfly that is hard to get rid of.” Not any longer, according to the decline statistics.
This can be risky if a mass emergence is in progress and a prolonged spell of bad weather strikes. I have seen this happen to the Marsh Fritillary on my transect on Lullybeg Reserve. A population crash occurs the following year because only a small number of individuals get to produce offspring. Recovery occurs over time, but in some cases, the entire population is wiped out. This is not disastrous when the population is functioning properly because the unoccupied site will be repopulated from a nearby colony. The problem arises when there is no nearby population.
The article does not dig into the reasons for the population decline. The reasons are deeper than weather conditions, relating to habitat availability, quality and likely, pollution from intensive farming and industry. That is for another post.
If you would like to establish a transect close to where you live to help monitor our and your butterflies, please email our recording partners: butterflies@biodiversityireland.ie
We must postpone the reserve management event planned for Saturday 24 February. The weather has been extremely wet, and the access routes are in very poor condition. Apologies for any inconvenience.
On the plus side, some Marsh Fritillary caterpillars on the reserve are out of hibernation. We look forward to counting and monitoring them over the coming weeks.
Butterfly Conservation Ireland’s reserve’s butterflies continue to thrive (see the reserve report in our Annual Report: https://butterflyconservation.ie/wp/butterfly-conservation-ireland-annual-report-2023/), even though the National Biodiversity Data Centre analysis of the 15 most common butterfly species show a -57% decline in the number of butterflies flying in 2022 compared to the baseline year of 2008.
A special thanks for the continued support from all our members and friends.
Fourth instar Marsh Fritillary caterpillars communal basking on Purple Moor-grass, Lullybeg, County Kildare.
Butterfly Conservation Ireland Annual Report 2023 is now available at https://butterflyconservation.ie/wp/butterfly-conservation-ireland-annual-report-2023/
We hope you enjoy this report. A free hard copy is available to all members on request. We are looking forward to the butterfly season in 2024 which we will report to you early in 2025.
The Comma had a great year in 2023 by continuing to expand its range in Ireland.
This week the EU’s climate service Copernicus published figures for 2023. The headline statistic is that the temperature rise recorded last year, for a year, was the highest they had ever seen on record. But are we getting as full a picture as we should be?
Global surface air temperature highlights arising from the Copernicus data:
2023 is confirmed as the warmest calendar year in global temperature data records going back to 1850.
2023 had a global average temperature of 14.98°C, 0.17°C higher than the previous highest annual value in 2016.
2023 was 0.60°C warmer than the 1991-2020 average and 1.48°C warmer than the 1850-1900 pre-industrial level.
It is likely that a 12-month period ending in January or February 2024 will exceed 1.5°C above the pre-industrial level.
2023 marks the first time on record that every day within a year has exceeded 1°C above the 1850-1900 pre-industrial level. Close to 50% of days were more than 1.5°C warmer than the 1850-1900 level, and two days in November were, for the first time, more than 2°C warmer.
Annual average air temperatures were the warmest on record, or close to the warmest, over sizeable parts of all ocean basins and all continents except Australia.
Each month from June to December in 2023 was warmer than the corresponding month in any previous year.
July and August 2023 were the warmest two months on record. Boreal summer (June-August) was also the warmest season on record.
September 2023 was the month with a temperature deviation above the 1991–2020 average larger than any month in the ERA5 dataset.
December 2023 was the warmest December on record globally, with an average temperature of 13.51°C, 0.85°C above the 1991-2020 average and 1.78°C above the 1850-1900 level for the month.
However, we need to consider the longer term to obtain a fuller picture of the recent history of our climate. By ‘recent history’ I mean the period since the last time Ireland, Britain, and much of northern Europe were dominated by ice 13,000 years ago. Sudden, dramatic changes have occurred during the past 13,000 years; sudden climate change is not new. 13,000 years ago all butterflies and likely most if not all of the other invertebrates would have been eliminated from Britain, Ireland and probably much of northern Europe.
Rapid warming occurred in the period up to c.11500 BC, with steadier warming thereafter: by 9000 BC, major ice sheets had been eroded significantly, though were (possibly) still in evidence in the highlands of modern-day northern Britain. As regards conditions over southern Britain, by c.11500 BC, it is estimated that mean winter-time temperatures were between 0 and 4°C (perhaps a little lower than today’s values) and high-summer values between 12 and 16°C, again a little lower or like current figures.
However, ice receded, but with the return of cold weather, over the following three thousand years. The severe downturn known as the ‘Younger Dryas’ reversal is thought to have started abruptly c.10,900 BC, reaching a depth of cold c.10,500 BC, when average temperatures are thought to have been mid-winter, -16 to -20°C (at least 15 °C below modern values – a truly dramatic fall) and high-summer, 8 to 12°C, about 4°C below modern values. This would have been disastrous – given the c.50yr period over which the decline is thought to have occurred: if it were to happen today, it has been argued that civilisation as we know it would cease. By 11,500 BC, most of these islands were ice-free. Butterflies and other invertebrates probably re-occupied these islands from about 10,000 BC. By 9500 BC, temperatures were back to pre-reversal levels. By 8400 BC the estimated temperatures were: mid-winter 0 to 4°C (like today) and high-summer 14 to 18°C. These figures represent a rapid increase, far larger and more sudden than is being reported by Copernicus since 1850.
According to the figures from Met Eireann, the seasonal mean temperatures for Ireland for 1991-2020 gives summer as the warmest season with a mean air temperature for Ireland of 14.6°C. Autumn is the second warmest season with a mean air temperature of 10.3°C, followed by Spring at 8.8°C. Winter is the coldest season with a mean air temperature of 5.4°C.
As you can see, even under a climate warming scenario, Ireland’s summer temperatures were up to 1.4 °C warmer in 8400 BC. In 5000 BC the mean temperature is estimated to have been 2 Celsius warmer than values in the second half of the twentieth century.
Around 3000 BC, the climatic limit of elm and lime trees moved northwards, and woods probably grew on Orkney and exposed areas in northern Scotland, suggesting less windy conditions than exist today.
However, around 2200 BC colder conditions returned probably arising from volcanic activity. Over time, mean temperatures fell and rainfall increased, and bogs developed. By 200 BC temperatures may have 2°C below those of the warmest post-glacial period.
(The source of this data is Weatherweb.net, the internet presence of Weather Consultancy Services Ltd (WCS). Established in 1997 WCS provides weather forecasts, climatological data and expert analysis worldwide, to customers ranging from farmers to multi-national PLCs. It contains information similar to that found in other specialist sources online.)
Estimates for climate change before weather recording began are derived from sources such as tree-ring dating, ice-cores, palynology (study of plant pollen, spores and certain microscopic plankton organisms (collectively termed palynomorphs) in both living and fossil form), population movements, settlement patterns, written sources after 3400 BC, etc.
According to Thomas (2014) between 8000 BC and roughly 3000 to 2000 BC average summer temperatures were 2-3 °C warmer than today but about 2500 BC the climate cooled by 2°C or more. This must have caused butterfly extinctions. The species sensitive to cold could only survive by finding unusually warm habitats, like those created by humans who were felling woods from c.5000 BC (from c.3000 BC in the Burren, interpreting the pollen record (D’Arcy 1992)).
The Marsh Fritillary requires unshaded grasslands rich in its larval foodplant, typically on south-facing and west-facing sites.
Species like Gatekeeper Pyronia tithonus probably became confined to the south coast of Ireland, in rocky areas which heated adjoining vegetation when the sun shone. Graylings Hipparchia semele would be likely to have retreated to areas devoid of tree cover where rocky and sandy habitats provided the heat-generating conditions they needed to grow their larvae. Other butterflies, like the Marsh Fritillary Euphydryas aurinia, are likely to have retreated to similar habitats and sheltered south-facing grasslands and large, sun-filled forest clearings.
In England, butterflies like the Silver-spotted Skipper Hesperia comma relied on areas cleared by humans and heavily grazed, where the grass was so short that soils baked in the summer sun. Woodland butterflies would have become dependent on coppiced woodland or areas in woods that were burned and allowed to recover.
Silver-spotted Skipper male, Box Hill. The plant is Small Scabious Scabiosa columbaria.
In the 1970s and early 1980s, the Silver-spotted Skipper had reached a nadir, found on just 20 or so downland sites in southern England. Anyone who recalls the weather during the period 1977-1982 will remember wet, cold summers. The Silver-spotted Skipper needs warmer conditions than any other butterfly in Britain, and by the early 1980s, it looked destined for extinction in Britain. Studies were organised to assess its biology and habitat needs to attempt its conservation. It can very extremely difficult, and expensive, to restore a lost species.
Silver-spotted Skipper, female, Box Hill.
The studies confirmed the climate and habitat constraints the species labours under in Britain. Female Silver-spotted Skippers strongly preferred Sheep’s-fescue Festuca ovina plants (a grass species) that were growing well but were no more than 2.5cm in diameter and with about three-quarters of their edges adjoining bare ground. The females were avoiding tussocks under 1cm that have their tips eaten (typically by sheep and rabbits). Therefore, the butterfly wanted a thin-soiled, south-facing southern downland with 40% bare ground, 45% coverage of small Sheep’s-fescue plants, and the remaining 15% occupied by nectar sources. The fussiness meant that the butterfly needed a rather bespoke solution of heavy sheep grazing outside July and August, with no grazing during these months and the recovery of the rabbit population after it was struck by myxomatosis. Sheep grazing was restored to the steep south-facing chalk downs, rabbit populations recovered and today there are over 250 colonies in England (Thomas 2014).
Another plus supporting the butterfly’s recovery is the increasing summer temperatures from the 1990s. Because the temperatures have risen, the butterfly has become less reliant on heavy grazing, with the species now using plants with as little as 20% of their edges abutting bare ground and less reliant on strongly south-facing sites (Thomas 2014). I noticed a considerable change in the sward at the Silver-spotted Skipper’s breeding site on Box Hill, Surrey, which I first saw in 1995 and again in 2018. The butterfly was just as numerous in both years, but in 2018 the sward was taller and had far less bare soil than in 1995. There were sheep present in 1995 and not in 2018. The warmer summers have helped. Between 1979 and 2019, the Silver-spotted Skipper abundance rose by 596% (Fox et al. 2023).
Box Hill, Surrey, 27 July 2018.
A warming climate certainly does not suit all our butterflies and has been implicated, in combination with nitrogen pollution, in the decline of species such as the Wall Lasiommata megera. But it would be dishonest to claim that it represents a disaster for all biodiversity. The expanding Comma Polygonia c-album, Brown Argus Aricia agestis, and Holly Blue Celastrina argiolus populations, among others, indicate that this is not the case. More research like that carried out into the biology and habitat requirements of the Silver-spotted Skipper is needed, because whether we agree with the way the climate data is presented, or the time scale used, climate change appears set to continue.
Accordingly, its effects on biodiversity must be assessed to shape policy and practice concerning our species and landscapes with particular emphasis on landscape-scale conservation to ensure a range of niches exist to mitigate climate impacts for species sensitive to changes in temperature and precipitation. Currently, climate change on its own is not an extinction risk to Ireland’s butterflies. The great damage being done today arises from habitat loss and changes to habitats arising from the intensification of farming. If climate change does threaten butterfly populations, it will likely do this in combination with pollution from agriculture and industry, and for some species, especially grass-feeders, this might be devastating.
The Comma is benefitting from the warming climate. It has colonised c. 20% of Ireland’s landmass during the period 2010-2021. Comma breeding in Ireland was confirmed as recently as 2014.
References
D’Arcy, G. (1992) The Natural History of the Burren Immel Publishing, London.
Fox R, Dennis EB, Purdy KM, Middlebrook I, Roy DB, Noble DG, Botham MS & Bourn NAD (2023) The State of the UK’s Butterflies 2022. Butterfly Conservation, Wareham, UK.
The short, dark days draw in so swiftly as 2023 hastens to a close. With Christmas to break the winter gloom, cheer is welcome, but the butterfly lover mourns the loss of colour and character that butterflies bring to life. Butterflies animate our world in ways no other creatures do. Their affinity with flowers creates multiple vistas of beauty and the irresistible power to fire imagination. Added to this palette is their link with bright sunshine that draws out colour, texture and form in ways nothing can, and perfection and happiness are defined. If this is not enough, our collective anxiety for the future of our Earth fixes attention strongly on the progress of butterflies. Butterflies are short-lived, respond rapidly to change and have life cycles that require different aspects of an ecosystem, are readily recordable so their population status offer an excellent barometer for environmental conditions. The decline and disappearance of the more sensitive butterflies sounds a silent alarm, like the canary who stops singing in a coal mine.
Winter in this part of the world is synonymised with death. The shadows deepen, sunshine is rationed, light at a premium, and clear only in cloudless skies. Our ancestors knew it too. At Newgrange they shared a part of their story about light with us, leaving behind a 62-foot-long passage terminating in a chamber flooded with light at the winter solstice.
But winter light does not necessarily bring comfort. It is sharp, piercing, and slanted, described in searing perfection by Emily Dickinson in her mood poem, There’s a certain Slant of light:
There’s a certain Slant of light,
Winter Afternoons –
That oppresses, like the Heft
Of Cathedral Tunes –
In the final stanza, the poet captures the universalised fear of winter’s cold, melancholy, unwarming, spiritually destructive light:
When it comes, the Landscape listens –
Shadows – hold their breath –
When it goes, ’tis like the Distance
On the look of Death –
The road we have left to travel is made clear by Dickinson.
The bleakness of winter drives many indoors, seeking the solace of the stove and central heating. However excessive indoor living is not healthy. Fleeing from the dying of the light, my past habits involved giving up on life until warmth returned in late March. But as my mental well-being discovered, that won’t do!
How does a lover of sunshine-dependent nature survive the winter? Applying a poetic licence, it is tempting to believe that winter kills all our butterflies. And there is certainly a foundation in science for this fallacy. Some adult butterflies, like the adorable Red Admiral pictured below, flee south to escape winter but most of our butterflies die off before winter’s shadows are even cast across the landscape. A few hardy species, four in total, hunker down to out-wait winter. Three of these (Brimstone, Peacock and Comma) are invisible to us. The part-exception is the Small Tortoiseshell, because it has a habit of entering occupied houses, among other sites, to seek overwintering accommodation. Thirteen Small Tortoiseshells in two plastic boxes lined with kitchen roll are residing in my fridge after the central heating woke them up. They have settled, all are alive, and will be released next spring.
Like plane loads of Irish people heading for warmer climes during December, the Red Admiral heads south, where it can still find food and warmth.
But what happens to the Small Tortoiseshell, Comma and Peacock during the winter in the wild?
All three overwinter with closed wings, choosing cool, dry, dark places to pass several months of cold weather. How well does this work?
All three have subtle underside colouring, all three usually settle in places that are dark and that allow their colours to blend with their surroundings. Not being seen in the first place is the first line of defence against the attention of hungry, insectivorous birds, especially Robins, Wrens, Blue Tits, and Great Tits. All three of these butterflies overwinter in woods and dense scrub, while Peacocks and Small Tortoiseshells will also use caves, disused buildings, and partly submerged pipes. A study conducted in Sweden (Vallin et al., 2005) compared the impact on all three species of Blue Tits. In the experiment, caged Commas, Peacocks, and Small Tortoiseshells were settled, so only the underwings were visible. The temperature was kept low to replicate winter conditions and encourage stillness in the butterflies. To have the chance to remain invisible, it is vital to remain immobile. Blue Tits were admitted to the cage for 40 minutes.
The Comma has a leaf-like outline and leaf-coloured undersides giving it an invisibility cloak when overwintering among drifts of fallen leaves or dense wooded cover.The Comma underside.
All the Peacocks and most of the Small Tortoiseshells (nine out of 15) flicked their wings open when the birds approached. The Peacock did this at a further distance from the birds than the Small Tortoiseshell. A sudden blaze of colour, the sound generated and perhaps the unexpected increase in size scared the birds. Every Peacock survived. The Peacock wing flashing, which is accompanied by a disconcerting hissing sound caused by friction generated during wing opening, caused the Blue Tits to flee. The wing flicking by discovered Small Tortoiseshells was not very effective. Overall, only 20% of Small Tortoiseshells survived, and only one discovered Small Tortoiseshell survived. In short, the Small Tortoiseshell is, it seems, heavily reliant on remaining unfound for survival. The Commas did not flick their wings open at any point, remaining still even if attacked. Overall, 67% of Commas survived.
The Peacock flashing eye-spots and snake-like hissing proved a deterrent to Swedish Blue Tits.
The Peacock was the most discoverable but proved more intimidating than the Small Tortoiseshell, which was better hidden, followed by the Comma which was found least often and made no attempt to intimidate. All three are edible to birds, so none of them rely on chemical defences to deter the Blue Tits.
One might wonder why Small Tortoiseshells flick their wings open given it proved mostly unsuccessful in scaring the Blue Tits. It should be noted that the butterfly only flicked its wings open when the bird was very close, and it is likely that it ‘knew’ it had been discovered and had to fall onto a new line of defence. While wing flicking did not prove very effective in this case, it might be more effective against other birds and other predators.
A flash of sudden, unexpected colour was not a strong deterrent against Blue Tits in the Swedish study, but the species has evolved this defence for good reasons. It might be sufficient against other predators or give it sufficient time to escape if it is warm enough to fly.
Peacocks have been found overwintering together, in large groups. Given its ability to intimidate, overwintering in numbers makes sense; if a single Peacock can scare a Blue Tit, how intimidating is the combined impact of several flashing, hissing creatures?
The other Irish butterfly that passes the colder months as an adult but was not included in the study is the Brimstone. It uses different overwintering quarters to the three members of the Nymphalid family, selecting greenery to blend with its leaf-like appearance. Brimstones overwinter in clumps of ivy, under bramble leaves where bramble grows among other scrub and open woodland and probably in dense holly, yew, and Greater Tussock Sedge Carex paniculata. When a sleeping Brimstone is approached, it does not flick its wings open and remains immobile, even when handled. It likely relies, like the Comma, on being undiscovered.
A female Brimstone on Common Knapweed. Notice the ivy leaf shape and foliage venation which must provide excellent camouflage.
What can one do to continue to enjoy butterflies in the off-season? One way is to read journals, books and new research, especially involving our native butterflies. Another way is to plan our butterfly gardens for the coming season. Another is to study butterflies that remain active during the colder months, not as adult butterflies, but in the caterpillar stage.
Rearing butterflies is a great way to do this. There is much that can be learned from rearing butterflies outdoors, in the open, to reproduce natural conditions as much as possible.
Currently, I am rearing Speckled Wood caterpillars. The caterpillars arose from eggs I obtained from two females I caught on 2 September. After laying several eggs, the butterflies were released. The eggs hatched just before mid-September, all within about two days.
A newly hatched, first instar Speckled Wood caterpillar from mid-September 2023.
The Speckled Wood caterpillar undergoes four instars (growth stages). Each instar ends when the caterpillar sheds its skin and enters the next instar or pupates after reaching full size at the end of the final instar. My Speckled Wood caterpillars are showing different growth rates, despite arising from eggs laid at the same time, hatching at almost the same time, and feeding on the same plants. Some of the caterpillars are in the third instar, others are in the fourth instar (this is the final instar before pupation), but none of these fourth instar caterpillars are fully grown.
Third instar Speckled Wood caterpillar from late October 2023.
The Speckled Wood butterfly is unique among Irish and British butterflies in being able to overwinter as a larva or pupa (Speckled Woods I reared from eggs that hatched in late July have reached the pupa stage). However, the available research, from caterpillars observed in Britain, shows that the Speckled Wood larva can only survive the onset of cold weather in the third instar.
Speckled Wood fourth instar caterpillar from eggs laid in late July 2023.Speckled Wood pupa formed by the caterpillar shown above. The first and second generations of the Speckled Wood fly over an extended period, resulting in eggs being laid over a long period and caterpillars at very different stages of development throughout most of the year.
If this holds for Irish Speckled Woods, my fourth instar caterpillars have a problem. Their only chance to survive is to complete their development and pupate before the cold weather strikes and feeding and digestion become impossible. They were still busy feeding today (10 December 2023), and they certainly need to continue, because these currently measure 20mm, and need to reach about 30mm before they are fully-fed. I suspect that nocturnal feeding occurs even in December, with caterpillars being found high on the foodplant beside recently nibbled grass. If these are in a race against time, they are taking full advantage of the milder nights with the night-time temperature of nine Celsius at 19:00 on 10 December.
Will they make it? How will this play out? Will I discover that the fourth instar Speckled Wood caterpillar can withstand the generally mild Irish winter? Is it more flexible than was thought? Butterflies and the natural world generally can keep us immersed year-round if we continue to engage!
The Speckled Wood flies in two extended generations each year, and in some years might produce a third generation.
Key Reference
Vallin, A., Jakobsson, S., Lind, J. & Wiklund, C. 2006, “Crypsis versus intimidation–anti-predation defence in three closely related butterflies”, Behavioral ecology and sociobiology, vol. 59, no. 3, pp. 455-459.
Sunshine, companionship, and conservation combined at Butterfly Conservation Ireland’s reserve at Lullybeg on Saturday 11 November.
We have endured torrential rain at the reserve and in Ireland in 2023. In March, April, July, August, September, and October the country had above-average rainfall, with July being the wettest month on record at 12 weather stations. November has been wet so far, but not on Saturday. Much of the northern section of the reserve has benefited from recent cattle grazing, and we plan to resume the grazing next spring, because the cattle still have work to do, with a very dense sward resulting from the year’s rain.
Our own remit on Saturday was simple: uproot as many saplings as we could in a section of flower-rich grassland. We worked in a line, uprooting as systematically as we could. Uprooting birch and willow is far better than strimming the vegetation. Strimming means you cut plants you don’t intend to target, and the saplings re-grow. Uprooting means saplings do not return.
The threatened Small Purple-barred moth breeds on Common Milkwort in the area of grassland we worked to conserve.
Some denser areas of taller scrub need strimming, but our uprooting work involved plants c.30cm or less in height.
Another benefit of working close together is the catch-up chats, which is always a great feature of our work parties.
Working without machinery means you hear more: that screeching Jay, the short, clipped call of the Great-spotted Woodpecker, and the chip-chip call of the flock of around 30 Crossbills, flying high among the plantation Lodgepole Pines.
The Dark Green Fritillary uses the area for feeding, but we did find violets in this grassland, so breeding might be possible in this grassland.
Our work was punctuated by lunch in the sunshine, a restful experience after a busy year on the reserve. We also unveiled our reserve information board, to some merriment and delight.
We know the wildlife on the reserve benefits from the work we do; that is the payoff!
Thanks to everyone who worked hard yesterday, and to all our supporters.
It is great to have some positive news to report. Butterfly Conservation Ireland’s reserve at Lullybeg has benefitted from a generous grant provided by Kildare County Council and the Department of Housing, Local Government and Heritage (NPWS). This article describes the reserve and explains how the grant has been applied to fulfil our conservation objectives.
Lullybeg Nature Reserve is a Bord na Móna rehabilitated cutaway, managed since 2010 by Butterfly Conservation Ireland (BCI). It is listed in the Bord na Móna Biodiversity Action Plan 2016-2021. It is described as a site of national importance in the Kildare County Development Plan 2023-2029. The reserve contains a butterfly transect walked up to 26 times each year between 1 April and 30 September. The records for the transect have been sent to the National Biodiversity Data Centre each year from 2008-2023. A report concerning the transect is published on the BCI website annually as part of the Annual Report. Lullybeg Reserve is bounded by plantation forestry to the north and east and bare peat to the south and west. It lies on both sides of a waterway that is part of the Crabtree River.
The site contains several habitats existing as complex mosaics. Habitats found on the reserve include tall herb swamps, ponds, marsh, wet grassland, dry-humid acid grassland, dry calcareous and neutral grassland, wet heath, poor fen and flush, scrub and bog woodland. This is an important conservation location (rated Nationally Important) as it is home to a population of Marsh Fritillary Euphydryas aurinia, the only protected species of butterfly in Ireland (protected under Annex II of the Habitats’ Directive 1992). Other important butterflies present are Dark Green Fritillary Speyeria aglaja (ranked Vulnerable), Wall Brown (ranked Endangered) and Small Heath Coenonympha pamphilus (ranked Near Threatened). Twenty-six butterfly species have been recorded on the reserve.
The Marsh Fritillary, Lullybeg Reserve, 2023
The rewards of conservation management and scrub removal/control are evident as the already impressive list of flora and fauna recorded on site is increasing. As stated earlier, the site is used as a transect for the Irish Butterfly Monitoring Scheme (IBMS) run by the National Biodiversity Data Centre, with 15 years of IBMS records underlining the site’s importance for Lepidoptera.
The Small Purple-barred moth, ranked vulnerable, flies in two generations at Lullybeg.
Moths that are present on the site include species ranked Near Threatened on the macro-moth Red List published by the National Parks and Wildlife Service in 2016 (Allen et al. 2016), such as Small Chocolate-tip Clostera pigra, Dark Tussock Dicallomera fascelina, Small Purple-barred Phytometra viridaria, and species ranked as Vulnerable, such as Narrow-bordered Five-spot Burnet Zygaena lonicerae. Birds such as Teal (Amber-listed), Woodcock (Red-listed), and Snipe are among the breeding birds present. Merlin (Amber-listed), Buzzard, Kestrel (Red-listed), Sparrowhawk, Jay, Raven, and Linnet (Amber-listed) occur here.
Flower-rich grassland on Lullybeg Reserve.
The conservation work required consists mainly of scrub control and cattle grazing. Scrub must be controlled to maintain plagio-climax vegetation of flower-rich grassland, wet heath and fen with low scattered scrub over much of the eastern half of the reserve. The work of scrub control is labour-intensive and is done by hand and using power tools. Grazing is a vital conservation tool for maintaining grasslands for butterflies, moths and other invertebrates. A range of sward heights and periodic substrate disturbance is vital for habitat maintenance. To contain the livestock effectively, fixed and movable fencing is needed, as well as a safe, clean water source.
The National Parks and Wildlife Service is aware of the reserve and its importance. NPWS held a Marsh Fritillary survey methodology training day on the reserve, led by the state entomologist Dr. Brian Nelson. Butterfly Conservation Ireland’s Board of Directors includes Mr. Kieran Buckley recently District Conservation Officer for NPWS in County Kildare.
An annual report is written to describe the butterfly abundance trends on the reserve. These reports, titled Lullybeg Reserve Report, can be found under the Annual Reports tab on the Butterfly Conservation Ireland website. The most recent report, from 2022, can be found here:
The grant aid, processed by Bridget Loughlin, the Heritage Officer in Kildare County Council was applied to the purchase of materials to manage the reserve. The fencing materials bought were conduction tape, fence posts, an electric battery, and a fencer. These were used to erect mobile fencing in the northeast section of the reserve in preparation for grazing by cattle.
In addition, fixed fencing containing gates were installed along the front of the reserve to ease access for visitors and to make delivery of livestock to the reserve more manageable. An information board was produced to introduce the reserve and acknowledge the support of Kildare County Council and the Department of Housing, Local Government and Heritage (NPWS).
The addition of the drinking trough and pump means the livestock have access to clean drinking water, making it more attractive to the farmer who provides the cattle to graze the site.
The power tools purchased, chain saws, pole saw, strimmer, and hedge trimmer will enable BCI to manage the reserve. The strimmer has been used to cut the vegetation under the fence to prevent it from interfering with the electric current. The chain saws have been used to clear an area of dense scrub to extend the grassland and reduce shading in an area that has the potential to host the Marsh Fritillary butterfly.
The pole saw and hedge trimmer will help BCI maintain the habitat by keeping developing scrub under control. These tools have a long reach making the dense scrub easier to tackle.
Safety equipment to operate the tools safely supports BCI’s volunteers.
Posts holding conduction tape above the sward trimmed using the brush cutter.Cattle grazing the reserve following fence installation, 22 October 2023.Scrub piled up beside a freshly cleared area, October 2023.
Fencing is installed with gates to allow visitor access and is convenient for cattle delivery to the reserve. Photos 26 October 2023.
BCI expects the support provided to assist us in protecting this very important reserve. The latest data published in the Irish Butterfly Monitoring Scheme Newsletter by the National Biodiversity Data Centre concerning butterfly abundance is deeply concerning (Judge and Lysaght 2023).
The new gates and fencing secure the reserve.
Results from the multi-species index of the 15 most common butterfly species highlight that there was a moderate decline (-57%) in the population of butterflies in 2022 when compared to the baseline year of 2008.
The Small Heath occurs in wild grassland in a number of habitats, from coastal grasslands to upland heaths, this formerly common butterfly is in retreat throughout much of Ireland’s farmed land.
It is important to note that the multi-species index is a useful index to show overall trends in population changes of common butterflies of the wider countryside. However, it does not generate sufficiently reliable data to track how the populations of our more localised or specialised butter-fly species are changing. This is because there is currently not enough data being recorded for these species. In order to capture adequate information on these species additional species-specific schemes (like the Marsh Fritillary Monitoring Scheme) are needed.
The Marsh Fritillary is monitored on the reserve and continues to thrive, but there are indications that it is declining elsewhere. The most recent government report to the EU Commission concerning the Marsh Fritillary indicates that it is not in favourable status.
Perhaps of greater importance is the decline of non-specialist butterflies. The 2023 Irish Butterfly Monitoring Scheme Newsletter reports a strong decline for the Ringlet and Meadow Brown, both thriving on the reserve. The decline of common species suggests a deeper, more widescale biodiversity loss.
Ringlet on Common Spotted Orchid. The Ringlet is booming on Lullybeg Reserve.
It is hoped that the management of the reserve will continue to show the way to protect our countryside and species.
Finally, BCI would like to record its gratitude to Kildare County Council Heritage Officer, Bridget Loughlin for her help in processing the grant application, to the Kildare County Heritage Officer Maebh Boylan, and to Kildare County Council and the Department of Housing, Local Government and Heritage (NPWS) for the grant.
Key Reference
Judge, M and Lysaght, L. (2023). The Irish Butterfly Monitoring Scheme Newsletter, Issue 15. National Biodiversity Data Centre
October is the last month of the year to see butterflies in any numbers. What can be seen is even more crucially weather dependent, but this year’s October has seen some exceptionally warm weather, with some good abundance figures for the time of year.
Red Admiral, County Meath, 13 October 2023.
We are seeing some unseasonable behaviour. On 14/10/2023 I observed a courtship flight by a Red Admiral pair, and it appeared destined to culminate in mating. The gentle fluttering flight used by both sexes is a sign of female cooperation in this butterfly, and if the pair remained in the lane instead of slipping quietly into an adjoining field, probably to seek shelter from the stiff north-west breeze, I feel sure that I would have observed their pairing.
I have never seen the Red Admiral behave like this in autumn in Ireland, so perhaps we are seeing the species beginning to stay put, even 33km inland, rather than migrating south, the situation that traditionally applies in Ireland. Since the turn of this century, coastal breeding in two areas (Howth, Dublin and Ravenwood, Wexford) during late autumn has been recorded, but not inland, where the colder conditions destroy the Common Nettle.
Painted Ladies were still being seen, inland and on the coast. Like their relatives, their main and probably only nectar source in many areas is our Common Ivy. While they remain, we are holding on to the memories of summer.
Painted Lady basking.
Another feature of change that has extended the pleasure of seeing butterflies deeper into autumn is the spread of the Comma, and its ability to produce a second generation in Ireland, a generation that hatches from the pupa in September and October.
Comma male, 14 October 2023, County Meath.
This lovely addition to our butterfly fauna can be seen sunning its gleaming orange-red wings on shiny bramble and ivy leaves, feeding on their fruit and flowers respectively. After the feeding is complete, the Comma hides itself in dense wooded cover until spring’s rays warm it to action.
In some woods, a dozen or more will be found in March feeding on a flowering Grey Willow. Slightly later, dandelion comes on stream. By the time this occurs, the males are defending territories and seeking passing females.
A final stage Speckled Wood caterpillar. This is likely to pupate soon and the adult butterfly will emerge in April or May 2024. Many Speckled Wood caterpillars present in October are much smaller and will pass the winter in the caterpillar state. For these, pupation will take place in spring 2024 and the adults will fly in May and June.
What is much less visible is the activities of moth and butterfly caterpillars, many of them still busily feeding before colder weather pauses their activity. Autumn moths are still in flight, such as the Merveille du Jour pictured here. Last weekend I had 19 moth species in my garden trap, a good showing for October, but the night I trapped was very mild.
Merveille du Jour, 14 October 2023, County Meath.
At this time of the year, sunny, sheltered south-facing hedges containing flowering ivy are the best places to look for butterfly life. In a week or so, even these places will hold little evidence of a fine summer for many of our butterflies, leaving us with our memories but also our hopes for next spring.
