Biodiversity Ireland Issue 2 Autumn/Winter 2023 is 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 since 2008, the baseline year for transect recording in Ireland, 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 very 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.
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. Declines in the numbers of common butterflies are worrying because these are highly 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.
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.
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, probably to spread 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.
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: firstname.lastname@example.org
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.
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)).
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.
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.
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).
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.
D’Arcy, G. (1992) The Natural History of the Burren Immel Publishing, London.
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.
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.
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 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.
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.
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.
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.
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.
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!
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.
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.
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 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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
Time, like an ever-rolling stream bears all its sons away; they fly forgotten, as a dream dies at the op’ning day.
(O God Our Help in Ages Past, Isaac Watts, 1674-1748)
Since humans learned to manipulate the environment to produce food, the natural world has been changing. Some people try to help nature by trying to restore what once was. Conscious not just of nature’s fragility but also of our mortality, the desire to leave something good that will outlast us is a powerful motivation. The following article reviews, briefly, what we have lost, describes efforts to reintroduce lost butterflies, and assesses the validity of reintroductions.
Animal and plant population loss is a common theme across the world. Humans have been radically altering the natural environment for thousands of years, especially since the farming of plants and animals began during the Neolithic period about 12,000 years ago. Mesolithic man was a hunter-gatherer, who moved through the landscape, surviving on food he picked, dug and hunted. There were no permanent settlements, and in Ireland and in other places, he used waterways to reach new areas to find food. Plant and animal domestication made long-term and permanent settlements possible, and humans began to replace natural vegetation with crops and grazing for animals.
Animals that threatened domesticated animals were killed when this was possible, and humans learned to protect livestock using dogs, and walls and by removing habitat for predators. Determined attempts were made to extirpate predatory animals, with rewards offered for proof of kills. The environment we have inherited is quite different from before farming was used to feed people and build civilizations; the pollen records and archaeological evidence show evidence of radically altered ecosystems.
The Brown Bear, the Eurasian Wolf, Wild Boar and Giant Elk are long extinct from Ireland and Britain, with the Giant Elk lost from the world, a likely victim of overkill and perhaps natural climate change. Many habitats are at a fraction of their original extent, and no fully natural habitat exists in these islands and in most of Europe. What these looked like is very difficult to say; there is recent research that challenges the long-held view that woodland dominated our landscapes before humans dominated them. The widespread presence of open grassland invertebrates today suggests that large areas of natural grassland must have existed.
The pollen record is not an infallible guide; some plants produce far more than others and some plant pollen travels further. Scots Pine falls into these categories; we cannot deduce huge pine forests existed simply because its pollen is abundant in the archaeological record. The pollen record does indicate that grasslands existed along with woods.
A mixed landscape of wooded and more open areas is now believed to have existed before the onslaught on forested areas by humans. When we began reafforestation early in the 20th century, we decided to use fast-growing non-native coniferous trees which lack any relationship with the woods we once had, and this approach, recently modified in favour of including some native trees, has continued. The most severe recent habitat loss in this country following the loss of native woods and grassland is our raised bogs, mostly destroyed. I doubt there is a single raised bog in Ireland that is undamaged.
Animals and plants require suitable conditions for their survival. When a species is lost from an area, it is usually because important conditions it needs no longer exist on a sufficient scale. You cannot, for example, plough a field containing wild grasses and herbs and re-seed it with agricultural grasses and White Clover and expect all the original insects it supported to survive.
There are people who dream of landscapes filled with beauty, containing the species we know once existed more widely. We cherish the often-small areas that still hold these natural features and want them protected and restored. Restoration involves returning existing habitats to their best condition, usually through some form of direct management.
Some go further; rewilding is their goal. Rewilding is the restoration of an area of land to its (original) natural uncultivated state; the idea is to remove human influence. In pursuit of these dreams, some people want to return animals that once existed in our environments. This has happened in Ireland, with the state-funded projects to restore the extirpated Golden and White-tailed Sea Eagles and Red Kite. Eurasian Beavers were reintroduced to parts of England and Scotland, many unofficially. Beavers are sometimes admiringly referred to as “ecosystem engineers”. By damming streams, they reshape valley bottoms, creating new ponds and waterways that rapidly fill with birds, amphibians, dragonflies, and other insects and fish. Research also shows how dams filter polluted water, and store huge quantities of floodwater. Beavers’ dams can even prevent towns from being flooded. But the water must go somewhere – and the farmers whose fields are flooded as a result tend to detest these rodent engineers.
One animal group that might be less controversially reintroduced is Lepidoptera, butterflies and moths. Some are easy to breed and easy to introduce. Just to be clear, reintroduction is the intentional movement and release of a species within an area that was once part of its historical range, but from which it has become extinct.
This has occurred in well-organized ways in England, with the reintroduction of the Large Blue (wiped out in 1979) and Chequered Skipper (went extinct in 1977). These reintroductions were underpinned by painstaking research and habitat restoration; the stock for the reintroduction of the Large Blue was sourced from Sweden while the Chequered Skippers were taken in Belgium.
But these were professionally executed and scientifically informed. Some people, however, are impatient with the slow progress of official reintroduction programmes and have decided to do it themselves.
Martin White from Nottinghamshire was a rewilder passionate about the reintroduction of extinct butterflies. He bemoaned the slow pace and cost involved in official reintroductions. He said that his first attempt to reintroduce the Mazarine Blue cost him less than £10. Contrastingly, official programmes cost much more. Transporting the Chequered Skipper to Rockingham Forest, Northamptonshire (north of Milton Keynes) via Eurostar cost £10,000.
White has introduced thousands of butterflies to various places; many of these efforts failed. But some succeeded; he closed a 90-mile gap in the Marbled White’s distribution between the midlands and the Yorkshire Wolds. He reintroduced the Purple Emperor to Lincolnshire. He has introduced the Dingy Skipper onto former mine sites, with success. Some butterflies cannot reach suitable sites because the intervening countryside is so hostile to insects that seek to move. Migrating insects must brave herbicides, pesticides, foodless ground, and long distances to reach areas that have become suitable again. Unless you are a powerful species, like the Red Admiral, the chances of natural recolonisation are very low.
But will these efforts succeed over the longer term? If a butterfly or moth is missing from a site, there is reason for its absence. Unless dealt with, simply releasing fertilised females will not help, even if the larval foodplants still occur on the site. Some species have highly specific needs that extend far beyond the presence of their foodplant. What often seems to happen is that the released butterfly breeds for a year or two before dying out.
What annoys nature reserve managers is the clamour to ‘save’ a reintroduced butterfly that reached the reserve via the car boot. People want to see rarities, such as the Marsh Fritillary or Glanville Fritillary so insist on this one butterfly being accorded conservation priority. This can reach extreme levels of attention. The only known Marsh Fritillary colony in Lincolnshire (courtesy of Martin White) exists in two fields, 100 miles from the nearest colony. The caterpillars are collected by volunteers and replaced on their foodplant after the area is mown. This is certainly not natural, and one wonders what the argument is for artificially maintaining this population. This is a gardening exercise, not a conservation one.
What is perhaps a more serious concern is using butterflies sourced in Europe to reintroduce a butterfly to an area in Ireland or Britain when the species still occurs in these countries. For example, Purple Emperors sourced in Germany were used to re-populate woods in east England. This might be harmful to native populations of the butterfly if pests or pathogens arrive with them. It might also change the genetic makeup of native Purple Emperors, which may have developed the genome to cope with English conditions.
There is evidence that introduced or reintroduced butterflies might create difficulties for other butterfly species. The arrival of the Map butterfly in southern Sweden (which it reached unaided) coincided with increased rates of infection by parasites of two other nettle-feeding butterflies, the Small Tortoiseshell and Peacock.
The three species’ caterpillars overlap in their occurrence, but there are phenological differences (differences in the timing of the hatching of the caterpillars).
The Map might be causing higher infection rates by shared parasitoids by providing a host for the parasitoids when the larvae of the Small Tortoiseshell and Peacock are scarce.
Therefore, there are times in the year when Map larvae are plentiful but those of the Peacock and Small Tortoiseshell are less numerous. Phenological differences in the parasitoids between hosts might also mean the Map is assisting increased infection rates in its butterfly relatives. If correct, the Map is reducing the competition for its food (nettles) during its establishment phase, but if the Map recruits more parasitoids, as the Swedish study indicates is likely, a balance between these butterflies might be struck.
But the study did not look at the parasitoids that the Map may have introduced to the other three butterflies, only looking at shared parasitoids, and looked at larval parasitoids, not egg or pupal ones.
The relationships are therefore not well-known and extrapolation from the Swedish experience may not be possible in another area with different conditions. Therefore, harm might be caused to native populations by reintroducing a butterfly or moth; however, after establishment, a balance might develop as the new arrival becomes subject to biological controls.
This is where the need to investigate impacts arises. The most useful step is to protect existing habitats, restore them where needed and extend them so that populations can move through the landscape. Where large areas of suitable habitat exist whether this is mainly the result of long-term favourable management, restoration, rewilding, or natural processes, then the conditions for the reintroduction of animal or plant species might be reached. Given the state of our habitats, reintroduction might even be necessary.
The severe reduction in the area of the Small Blue’s habitat along the Dublin coastline due to serious coastal erosion, management problems and the creation of golf links prompted an introduction of the species in extensive suitable habitat in County Meath and Louth. This attempt has been very successful. Meanwhile, the donor population has lost about 90% of its original habitat, which has been swallowed by the sea. The remaining population is hanging by the proverbial thread.
If the dune habitat on the donor site is restored by natural or human action, the new populations might return the compliment! This has already happened in England. Black Hairstreak butterflies from Monk’s Wood, Cambridgeshire were used to establish a new population at Warboys Wood. When Monk’s Wood lost its population during the Great War, it was repopulated from its receptor site. The restored Monk’s Wood population still exists to this day!
Considerable resistance to unauthorised, unofficial reintroduction exists and has for some time. It is illegal to introduce an exotic animal into the wild in Ireland and illegal to introduce or reintroduce, without consent, any animal or plant not already present in certain protected areas after a Statutory Instrument has been signed. It is a great pity that this is not the case for non-native plants in the general countryside. Biological recorders resent their maps being compromised by records of unofficially released species. This makes it harder to calculate the true distribution of a species, especially given the often transient presence of introduced species. Others hate the idea, captured in naturalist Robert Lloyd Praeger’s phrase of ‘forging nature’s signature’, by introducing species in areas where they might never have occurred.
There are very good reasons for not interfering with nature. There are very good reasons for interfering with nature. In the absence of good motives and good research, reintroduction should not be tried. Bad motives include removing rarities from a site because it is about to be destroyed by a development or introducing rarities to a site that is about to be destroyed by a development. Martin White carried out his introductions because he loved butterflies and wanted to leave a legacy, to feel that his life was not a waste. Martin White died on 12 October 2020. He knew his time was coming months before. He was still releasing butterflies in the summer of 2020. Whatever the ecological impacts of his efforts, it is touching to see his drive to see nature flourish.
The damage we have done places a moral obligation on us to atone. Reintroductions might be part of this process. It might be a question of how these are done, not whether they are done. But let’s focus chiefly on looking after our habitats and extending them. Without good, large-scale habitats, many species don’t stand a chance.
Audusseau, H., Ryrholm, N., Stefanescu, C., Tharel, S., Jansson, C., Champeaux, L., Shaw, M.R., Raper, C., Lewis, O.T., Janz, N. & Schmucki, R. 2021, “Rewiring of interactions in a changing environment: nettle‐feeding butterflies and their parasitoids”, Oikos, vol. 130, no. 4, pp. 624-636.
The extraordinary garden of Robert Donnelly and Jane Doughty boasts enormous butterfly populations, with hundreds of butterflies counted for Butterfly Conservation Ireland’s National Garden Butterfly Survey annually. On just one day, 27 August 2020, 154 Small Tortoiseshells were counted, feasting on native flowers such as Hemp Agrimony Eupatorium cannabinum. Less frequent garden visitors, such as Cryptic Wood White, Small Copper, Comma, and Silver-washed Fritillary also make Robert and Jane’s garden at Little Eden in County Kilkenny their home.
But Little Eden is not just looking after local butterflies. The garden’s fruit and vegetable yield generated €793.42 from neighbours and passers-by, which Robert and Jane have kindly donated to Butterfly Conservation Ireland. Their help is timely, as we are currently arranging fencing for the front boundary of the reserve in Lullybeg in northwest Kildare to improve the security of the area to ensure grazing livestock needed to conserve the grassland habitats are better contained.
A great thanks to Robert and Jane for all they do for butterflies local and national. The joy of seeing beautiful butterflies in our gardens and beyond, like this Red Admiral, depends on the care for nature shown by Jane, Robert, and all our members and supporters.