Under the Habitats Directive 1992 certain geological features, habitats and species must be protected within Special Areas of Conservation (SACs). One of the species is the Marsh Fritillary butterfly. Ireland had to identify areas important for the Marsh Fritillary butterfly and designate the areas as Special Areas of Conservation. This was required of European Union countries with populations of the butterfly. Where an area is designated for the butterfly, the butterfly is named as a ‘qualifying feature’ for the Special Area of Conservation. A full list of Ireland’s SACs can be found here:

https://www.npws.ie/sites/default/files/files/SAC%20quick%20reference%20table(1).pdf

Ireland listed 12 SACs with the Marsh Fritillary as a qualifying feature (in each SAC, other qualifying features are listed too). The 12 sites are listed here: https://www.npws.ie/protected-sites/search/by-feature?feature%5B%5D=6133&designation%5B%5D=375

A check of the documents available concerning each site on the National Parks & Wildlife Service website makes for interesting reading. The documents consist of

1. Conservation Objectives: these aim to define favourable conservation conditions for particular habitats or species at that site. The Conservation Objectives state whether the Marsh Fritillary is present and the area of suitable habitat within the SAC.

2. Site Synopsis: this states the site location, and summarises the habitats, species, and importance of the site and comments on any threats to the site’s conservation values.

3. Statutory Instrument (SI) and SAC maps: The SI designates the SAC, states the qualifying feature species and habitats, and sets out the activities that require ministerial consent. The maps identify the area occupied by the SAC.

What do the Conservation Objective Reports tell us?

The Marsh Fritillary was recorded in just four of the 12 SACs. These are:
1. Bricklieve Mountains and Keishcorran SAC
2. East Burren Complex SAC
3. Moneen Mountain SAC
4. West of Ardara/Maas Road SAC

My records indicate it is extinct in Ballynafagh (last recorded 1999) and Killarney (last recorded 2006), the report for Barrigone states that there are no confirmed records for that site. Remarkably, the Barrigone report states:

The association of the species with the SAC derives from a paper by Lavery (1993) which refers to a site called Foynes/Barrigone as being one of three major populations in Ireland. A survey in 2012 did not find the species in the SAC (Wilson et al., 2013).

Was Lavery correct when he wrote the paper? Was Lavery’s word taken without an NPWS site survey? Why is the area designated to protect a butterfly that does not occur there?

The area occupied by the Marsh Fritillary at Barrigone has dried out and is now overgrown with scrub. Geoffrey Hunt, a reliable recorder searched the area regularly since 1998 and has not seen any Marsh Fritillary on the site. Geoffrey’s knowledge of the site raises questions concerning this statement from the site’s Conservation Objectives report:

In 2012, just over 9ha of habitat was assessed as suitable for the species (NPWS, 2019).

Is there any suitable habitat remaining at Barrigone?

The Conservation Objective reports for the following four sites where the Marsh Fritillary is a qualifying feature for the SAC do not even mention the butterfly:

1. Bunduff Lough and Machair/Trawalua/Mullaghmore

2. Gweedore Bay and Islands SAC

3. Sheephaven SAC

4. St. John’s Point SAC.

I have visited Bunduff Lough and Machair/Trawalua/Mullaghmore SAC (the terrestrial area is 1,812.12ha) and St. John’s Point SAC (the terrestrial area is 152.08ha) and found larval webs on these sites. However, while I did not measure the area of suitable habitat present on these sites, the areas are not extensive.

I calculated the combined area of the SACs (excluding maritime areas for coastal sites) and, where the figure was provided, the area of suitable habitat for the butterfly. In two SACs, located in the Burren, the area of suitable habitat was estimated by NPWS, not measured. Combined, the 12 SACs contain 159,647.26 hectares. The total suitable habitat stated is 5,725.2 hectares.

The ratio of suitable habitat in hectares to overall terrestrial area in these SACs is 1:28. There is one hectare of suitable habitat for the Marsh Fritillary for every 28 hectares of land. The ratio of Marsh Fritillary habitat to total SAC land of 1:28 is problematic.

As the Marsh Fritillary occupies the landscape in a metapopulation structure there is a need for a network of sites within a region for the species’ long-term survival. In England, the minimum figure of 50ha (note: 50ha2 is ½ km2) of suitable habitat within an area of 16km2 (1600ha) is indicated by Bulman et al. (2007). (This ratio is 1ha:32ha.) The modelling suggests the species may persist in areas below this area for decades, but extinction will eventually result unless additional habitat is provided. Irish research is needed concerning this aspect (NPWS, 2019).

If the ecology and habitat distribution of the Marsh Fritillary reflect that in England, the combined figures for the 12 SACs designated to protect the species are below the minimum threshold needed for long-term survival.
Taken on a regional basis, only the two Burren SACs, which are extensive (but much smaller than the Connemara and Killarney SACs), contain habitat that exceeds the minimum required. The Burren SACs and the habitat and habitat ratios are:

East Burren Complex (18800.65 ha (188 km2 ): 3,200ha (32km2), ratio 1:6 and Moneen Mountain (6100ha (61 km2): 2,500ha (25 km2), ratio is 1:2.4.

A proper analysis of the minimum figure for regions holding the smaller SACs would need to factor in any suitable habitat in areas adjoining the SAC to assess the species on a regional basis. However, adjoining areas might not hold breeding habitat.

The absence of detailed management plans for some SACs is another problem. How do we know if the habitat is being managed correctly? The Burren’s populations are safe, for now.

This cannot be said of many populations elsewhere. Look at Barrigone, once regarded as one of the three major populations In Ireland. Look at Killarney and Ballynafagh, where it no longer occurs. These are sites where the preservation of the Marsh Fritillary is a conservation priority.  Protecting the butterfly, which means protecting its habitat, preserves many important habitats and species. The absence of the butterfly highlights poor habitat quality, bad practice and lack of care. The summative assessment is ‘poor result is due to the lack of any serious effort.’

The formative assessment is to ‘apply the required habitat management techniques to restore the habitat within SACs and expand the network of protected areas and appropriately manage these areas to at least meet the minimum habitat size of 50ha within 16km2 to ensure this lovely butterfly’s long-term survival.’

There are two areas set aside for nature where the land is managed specifically for the Marsh Fritillary. These are Butterfly Conservation Ireland’s Crabtree Reserve, Lullybeg, Kildare and the Irish Peatland Conservation Council’s Lullymore West Butterfly Reserve. Both sites hold long-term, thriving populations. It can be done.

References

Bulman, C.R., Wilson, R.J., Holt, A., Galvez Bravo, L., Early, R., Warren, M.& Thomas, C.D. (2007) Minimum viable metapopulation size, extinction debt, and the conservation of a declining species. Ecological Applications 17: 1460–1473.

NPWS (2019). The Status of EU Protected Habitats and Species in Ireland. Volume 3: Species Assessments. Unpublished NPWS report. Edited by: Deirdre Lynn and Fionnuala O’Neill

NPWS (2021) Conservation Objectives: Ballynafagh Lake SAC 001387. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.

NPWS (2019) Conservation Objectives: Barrigone SAC 000432. Version 1. National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht.

NPWS (2021) Conservation Objectives: Bricklieve Mountains and Keishcorran SAC 001656. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.

NPWS (2015) Conservation Objectives: Bunduff Lough and Machair/Trawalua/Mullaghmore SAC 000625. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

NPWS (2015) Conservation Objectives: Connemara Bog Complex SAC 002034. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

NPWS (2022) Conservation Objectives: East Burren Complex SAC 001926. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.

NPWS (2015) Conservation Objectives: Gweedore Bay and Islands SAC 001141. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

NPWS (2021) Conservation Objectives: Moneen Mountain SAC 000054. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.

NPWS (2017) Conservation Objectives: Killarney National Park, Macgillycuddy’s Reeks and Caragh River Catchment SAC 000365. Version 1. National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht.

NPWS (2014) Conservation Objectives: Sheephaven SAC 001190. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

NPWS (2015) Conservation Objectives: St. John’s Point SAC 000191. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

NPWS (2015) Conservation Objectives: West of Ardara/Maas Road SAC 000197. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

 

 

 

 

Butterfly Conservation Ireland Annual Report 2024 is now available. You can find it under the Report tab: https://butterflyconservation.ie/wp/butterfly-conservation-ireland-annual-report-2024/

We hope you enjoy the content. A hard copy is available free to all members of Butterfly Conservation Ireland.

On 1^st November 2024, the Irish Government published its response to the recommendations of the Citizens’ Assembly on Biodiversity Loss. This was done just before the General Election was called. The statement concerning the report can be found here:

https://www.npws.ie/news/government-publishes-response-recommendations-citizens%E2%80%99-assembly-biodiversity-loss

It claims:

Over 90% of recommendations are ‘In progress’ or ‘Implemented’

Work will continue across Government to address gaps, including through the forthcoming national Nature Restoration Plan

Report also includes responses to the ‘Calls to Action’ from the Children and Young People’s Assembly on Biodiversity Loss

The report can be read here:

https://www.gov.ie/pdf/?file=https://assets.gov.ie/310662/9af8b802-a500-464a-8501-577eed84797b.pdf#page=null

The government states that the National Biodiversity Action Plan was assessed by the Worldwide Fund for Nature and “was found to be the best in Europe and one of the best in the world.”

These are the Government’s claims. Do these withstand scrutiny?

What does the Worldwide Fund for Nature say about Ireland’s National Biodiversity Action Plan?

First, a definition: the Worldwide Fund for Nature references the Global Biodiversity Framework (GBF) when assessing National Biodiversity Action Plans.

In 2022, 196 countries agreed to halt and reverse biodiversity loss by 2030 under the Kunming-Montreal Global Biodiversity Framework. This is a historic deal for nature and a breakthrough for conserving and restoring biodiversity and ensuring its sustainable use. The GBF contains four goals and 23 targets. One goal is to

Substantially increase the area of natural ecosystems by maintaining, enhancing or restoring the integrity, connectivity and resilience of all ecosystems. Reduce by tenfold the extinction rate and risk of all species and increase the abundance of native wild species. Maintain the genetic diversity of wild and domesticated species and safeguard their adaptive potential.

(Source: https://lordslibrary.parliament.uk/cop15-global-biodiversity-framework/#:~:text=The%20GEF%20is%20an%20international,change%20responses%20in%20developing%20countries.)

The Worldwide Fund for Nature is highly complimentary about Ireland’s 4^th National Biodiversity Action Plan (NBSAP). It notes that the Plan addresses all the targets of the GBF.  These can be read in Appendix I of the Plan. Targets, clear actions and success indicators are stated.

However,  the Fund notes problems too. Areas lacking include no specific plans within the NBSAP to reduce the footprint of consumption within Ireland other than what is already in place (GBF Target 16); plans to address harmful incentives (GBF Target 18) do not go further than committing to implement a financial tracking system.  Overall, financing commitments and actions are weak. GBF Target 18 calls for the Governments to

eliminate, phase out or reform incentives: incentives, including subsidies, harmful for biodiversity, in a proportionate, just, fair, effective and equitable way by 2030, starting with the most harmful incentives, and scale up positive incentives for the conservation and sustainable use of biodiversity.

(Source: https://www.cbd.int/gbf/targets/18)

In the matter of financing the 4^th National Biodiversity Action Plan (NBSAP), the Worldwide Fund for Nature states:

In terms of financing, 3 billion euros have been allocated in Ireland’s 2024 Budget to an Infrastructure, Climate and Nature Fund which may include support for the delivery of the NBSAP but it is unclear how much will be dedicated to the NBSAP or to which action plans. The process to develop a National Biodiversity Finance Plan dedicated to NBSAP execution is underway which may yield more resources. 

The 4th National Biodiversity Action Plan is in place, but will it be implemented? And how well will it work?

Since this Government took office in 2020, some positive initiatives have been implemented. The state has ceased destroying peat bogs in its ownership and has re-wet a minority of the peatlands held by Bord na Móna. Coillte (state forestry service) is also restoring some peatland.  However, a negative lies in the failure to implement Recommendation 117 of the Citizen’s Assembly on Biodiversity Loss which provides:

All enterprise involved in the harnessing of renewable energy from or on all peatland must have a strict biodiversity net gain clause attached to their development permission and must be responsible for the ongoing and future management and enhancement of the biodiversity of their sites.

The result is likely to be the destruction of habitats and ongoing biodiversity loss from these peatland sites. The document provides no reason for this decision. Recommendation 50 of the Citizen’s Assembly on Biodiversity Loss is to

stop the use of harmful chemicals and pesticides. This would include: – Preventing people from spraying plants with pesticides and chemicals, and making sure farmers do not spread chemicals on the roads

This recommendation is not being implemented.

Of the 159 Recommendations of the Citizens Assembly on Biodiversity Loss, 134 (84.3%) are considered by the Government to be in progress, 15 (9.4%) are being implemented and 10 (6.3%) are not being implemented.

A huge amount of work has not been completed. Some of the targets in the National Biodiversity Action Plan, such as the notification of Annex habitats and species listed on the EU Habitats and Birds Directives and the development of management plans for Special Areas of Conservation should have been completed decades ago. The National Peatland Strategy 2015-2025 has missed important deadlines for the completion of actions. It is doubtful that some of these will be completed. Ireland remains without a national park holding a single raised bog, a priority habitat.

A complete review of the Government’s claims and progress is impossible here, but let’s look at some problems.

The Eurasian Curlew might cease breeding in Ireland. Its farmland and bogland breeding areas have mostly been destroyed. The Lapwing is in deep trouble for similar reasons.

The 2024 Irish Butterfly Monitoring Scheme report (which covers the 2023 flight season) contains stark news.

No resident butterfly species showed an increase in population size compared to 2008. During 2008-2023, four of our butterflies experienced a ‘strong decline’ and eight experienced a ‘moderate decline’. Two are regarded as stable while seven are rated ‘uncertain.’ Just one butterfly, the migrant Red Admiral, showed an increase. (Source: Judge, M and Lysaght, L. (2024). The Irish Butterfly Monitoring Scheme Newsletter, Issue 16. National Biodiversity Data Centre).

Next year’s report will show even bigger declines, owing to the poor summer weather in 2023 and 2024, ongoing challenges of shrinking habitat, pollution and climate change. If we were to judge the Government’s success in dealing with biodiversity based on the population levels of our butterflies, we would deliver a failure verdict.

Between 2008 and 2023, a population decline of 60% was recorded for the Common Blue, Wood White agg. and Speckled Wood. The Green-veined White, probably our most widespread species, fell by 82%.

You might ask the politicians and canvassers why so many of our landscapes cannot support abundant populations of once-common butterflies, birds, flowers and bees. Ask why Ireland insists on destroying biodiversity by clinging to its derogation from the Nitrates Directive and continues to use poisons and pollutants to grow food.

How many Small Tortoiseshell butterflies did you see in 2024? If common butterflies with no special requirements no longer thrive, the Government cannot claim success in protecting nature.

 

 

 

 

 

 

 

 

 

 

 

 

 

There is a track in Lullymore in northwest Kildare that runs in an east-west direction, about half of its length is open to the south while native woodland exists on its northern edge. The track was created by excavating marl and rises above the adjoining peat soils. The track holds a range of grasses, including Red Fescue, Cock’s-foot Grass, Sweet Vernal Grass, and Quaking Grass. Herbs include Common Knapweed, Rough Hawkbit, Common Dandelion, Common Bird’s-foot-trefoil, eye-bright, Common Dog-violet, Meadow Vetchling, and Devil’s-bit Scabious. Common Nettle occurs in different areas on both sides of the track. There are some areas of bare soil on the track created by vehicles.

The adjoining wood contains Bilberry, Bramble, Downy Birch, Grey Willow and Common Holly, with small amounts of Common Hawthorn. Broom and Bracken are present with the latter abundant in the shaded area on the southern edge of the track. Alder Buckthorn occurs near the southern edge of the track, on peat soil. The track leads to the Irish Peatland Conservation Council’s butterfly reserve.

The track is very popular with nature lovers. In spring and summer, many happy hours are spent in this space by nature lovers who can observe the large populations of insects that congregate here. From Hairy Dragonflies in May to Black Darters and Migrant Hawkers in late October, the track is a dragonfly haven throughout these months. And little wonder, given the large prey populations, warmth and perch points available.

Several butterflies visit the track and several breed on it. Dingy Skipper, Cryptic Wood White, Common Blue, Red Admiral, Small Tortoiseshell, Peacock, Comma, Speckled Wood, Meadow Brown and Ringlet breed on the site, while Wall Brown, a suspected breeder, is sadly now rare.

Brimstone, Small White, Green-veined White, Orange-tip, Silver-washed Fritillary and Marsh Fritillary visit for food and mates. The sheltered site encourages butterflies from adjoining areas to congregate here during windy conditions. This makes the track a place of abundance and a pleasant place for people to watch nature.

However, over recent years the experience has become less than it used to be. Shade cast by overhanging branches from the wood and the scrub on the track’s southern edge and the denser, more shade-tolerant grasses are lessening the floral resources and darkening and cooling the track.

Butterfly Conservation Ireland’s work party have begun to reverse these changes on our workday on Saturday 9^th November. Shading scrub and the shadow-casting overhanging branches were tackled and bramble, which favours semi-shade and has been swallowing up the herbs, was dealt with by our brush-cutter. Tough and inglorious the work might be, but the results are glorious. As usual, our tea and lunch breaks are not just welcome sustenance but great catch-up times, and happy times for sharing news and experiences. Sharing experiences with nature are great enhancement to appreciation.

We offer our heartfelt thanks to all our conservation workers for all the effort devoted to nature. We will have our next work party early in 2025.

 

We are baked into a biodiversity catastrophe. Observers who have lived over 40 years and those with access to long-term data might grasp how bad the natural world’s crisis has become. In Ireland, we moved from holding massive areas of intact wetlands containing large populations of breeding wading birds, to ugly, brown peat deserts many now with towering wind turbines, from vast flower-rich grasslands with their Skylarks, Meadow Pipits, Curlews and Corncrakes to empty factory floor astro-turf-coloured rye-grass monocultures maintained by climate-warming chemical inputs.

The baselines plummet ever downwards. And how do we react? Mostly not at all or with minimal tokenism. A little scheme here and there. Or worse. Kildare farmer Dermot Doran puts a pond in his farm that draws Kingfishers, Herons, Moorhens and Egrets. He did it because he loves nature. He spends €6000 in the process. Then his farm payment is cut. He is punished for doing the right thing—dumb and Dumber.

Bad practice abounds. Hedgerows are one of our crucial habitats. In a country with few native woods, our hedgerows assume great significance for nature. Most of our butterflies and large numbers of our moths breed in hedges or on the extended field margins and hedge banks. Bats and birds use hedges as their feeding zones and travel routes. Hedgehogs, frogs, Foxes and Badgers feed, rest, breed and hide in them. A species-rich hedge and adjoining grassland is a treasure. These habitats are biodiversity hotspots, give shelter and warmth, mark boundaries, retain livestock and add character to our countryside. Yet look at the miserable example below. Many are badly managed; cut severely like the one in the photograph or left unmanaged so they develop gaps.

Even nastier is the practice of removing sections of rural hedging to erect post and rail fencing usually followed by ‘garden shrubs’ like Escallonia (South America), Griselinia (New Zealand), Leylandii (derived from two species of cypress from North America ), Cherry Laurel (native to south-east Europe towards Iran) or some other bland blight on the landscape. These plants are not native support only a few native insects and don’t provide nectar, pollen and fruit like Common Hawthorn, Dog Rose, Field Rose, Honeysuckle, Blackthorn, Guelder Rose, and Bramble do.

A little less nasty is Common Beech. Beech isn’t native either and beech-only hedges look wrong in our countryside. The non-native hedging plants are typically the rubrics of suburbia now appearing in rural areas courtesy of one-off houses. They remove native species hedgerows and replace them with ‘plastic.’ These plants could be plastic as far as their value for biodiversity extends. No native butterfly breeds on any of these non-native plants.

Not happy with shiny laurel and Griselinia, many add sycamores, Himalayan Birch and ornamental conifers. A tree is a tree, right? We need more trees, don’t we? We need more of the right trees. Grow, according to the trees naturally present in your area, Mountain Ash, Irish Whitebeam, Common Whitebeam, Bird Cherry, Wild Cherry, Alder Buckthorn, Purging Buckthorn, Common Hawthorn, Grey Willow, Downy Birch, Common Hazel, Sessile Oak, Pedunculate Oak.

According to UK research,  1,178 invertebrate species use our native oaks (Sessile Oak, Pedunculate Oak) and 257 of them rely solely on these trees.[1] This does not include birds, bats, lichens, fungi and mosses using our native oaks. Taking every dependent and associated species, oaks support 2,300 species excluding bacteria and other microorganisms. [2]

To offer a little Lepidoptera context, only two of our large moth species use non-native Sycamore (the Small Yellow Wave and the Buff-tip, which also uses native trees). However, 71 of Ireland’s larger moths use oak.

It is simply a magical tree, long-lived, steeped in our culture, and needed by nature more than ever.

Another crime against nature is our addiction to chemical weapons. We poison wildlife. At the Orchard Garden Centre in Celbridge, I found shelves full of chemicals to kill wildlife. One of the products, Weedfree Plus promises to kill Dandelion, clover, speedwell, buttercups, and Creeping Thistle, among others. Dandelion, Red Clover and White Clover, Creeping and Field Buttercup and Creeping Thistle are among the best native flora for pollinators. The public is encouraged to let these flowers flourish by pollinator schemes while garden centres encourage us to poison them. Charming.

The safety instructions on Weedfree Plus advise users to ‘Avoid all unnecessary contact with this product’. Excellent advice.

There is an obsession with slug and snail killers. What are Song Thrushes, frogs and Hedgehogs supposed to eat?

Elsewhere in the garden centre, there is a range of bird food products ranging from dried mealworm to seed and nuts, fat balls, and bird feeders supported by a video on repeat showing Goldfinches frenzying over a feeder.

If we grow native flora in our gardens, we would not need supplemental feeding for birds. Dandelion and Creeping Thistle provide lots of natural food for Goldfinches.

One plant in the garden centre caught my eye; Cephalanthus occidentalis marketed as Cephalanthus Magical Moonlight and described as a ‘Butterfly Magnet’. The species is native to North America. It attracts butterflies there and is likely to attract Irish butterflies. Native herbs are targeted for eradication while non-natives sell for €19.95.

We need native plants to feed species native to our ecosystems. The best native shrub for feeding adult pollinators is probably Bramble. Nineteen of our larger moths’ larvae feed on the leaves. The fruit is eaten by birds and by several butterflies and moths, including the Small Copper and Speckled Wood butterflies.

We have destroyed most of our wetlands and farmland. We need to repair the damage, late as it is, but the right approach must be implemented across all habitats.

The home and garden are good places to begin.

 

 

 

 

 

 

 

 

[1] https://catalogue.ceh.ac.uk/documents/22b3d41e-7c35-4c51-9e55-0f47bb845202

[2] https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/oak-tree-wildlife/

Then Jesus said to his disciples: “Therefore I tell you, do not worry about your life, what you will eat; or about your body, what you will wear. For life is more than food, and the body more than clothes. Consider the ravens: They do not sow or reap, they have no storeroom or barn; yet God feeds them. And how much more valuable you are than birds! Who of you by worrying can add a single hour to your life? Since you cannot do this very little thing, why do you worry about the rest? “Consider how the wildflowers grow. They do not labour or spin. Yet I tell you, not even Solomon in all his splendour was dressed like one of these. If that is how God clothes the grass of the field, which is here today, and tomorrow is thrown into the fire, how much more will he clothe you—you of little faith! And do not set your heart on what you will eat or drink; do not worry about it. For the pagan world runs after all such things, and your Father knows that you need them. But seek his kingdom, and these things will be given to you as well.

(Luke 12:22–31)

During a sermon based on this reading last Sunday, the minister referenced butterflies. Immediately I focussed on the sermon. Striving for material success, wealth and fame was likened to butterfly hunting. Butterfly hunting was referenced as a shallow, empty, purposeless activity. I bristled. My fellow congregants know my propinquity to the world of butterflies.

This is the first time I heard of butterflies signifying vacuity although The Bible mentions moths as a corrupting force, symbolising the futility of a life lived for gain:

Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal:

But lay up for yourselves treasures in heaven, where neither moth nor rust doth corrupt, and where thieves do not break through nor steal:

For where your treasure is, there will your heart be also.

(Matthew 6:19-21)

This stimulated me to ponder the metaphorical references to butterflies. How do we view butterflies?

Are they just the objects of admiration for the shallow, or do they reflect the positive values of those who love them and the butterflies themselves?

The ITV dramatization of P.G. Wodehouse’s Cheeves and Wooster novels contains this exchange:

Roderick Spode: Because he’s a butterfly, who toys with women’s hearts and throws them aside like soiled gloves!

Bertie Wooster: Do butterflies do that?

In this exchange, butterflies are shallowly attractive, meretriciously compelling but ultimately deceitful. Nothing of integrity lies beneath the beguiling beauty of a butterfly. So far we have butterflies aligned with emptiness, greed, materialism and dishonesty. Not a pretty picture, despite their beauty.

Nothing so sweet can be wholesome. Yet butterflies have been deployed as symbols of spiritual living. In Maria van Oosterwijck’s Vanitas Still Life (1668) a Red Admiral is perched on a page accompanied by objects that appear to have little connection.   Beneath the somewhat faded butterfly is a piece of paper with a handwritten quote from the Old Testament’s Book of Job: “Man born of woman is of few days and full of trouble” – a passage that goes on to say, “He springs up like a flower and withers away; like a fleeting shadow, he does not endure.” It sounds bleak, but it is intended to liberate us from our addiction to luxuries. All the objects in the image show the passing of time (such as the timer and skull) and the ultimate futility of worldly possessions. The Red Admiral reinforces the theme; it will not live long, and its colours are already fading. The painting is a warning.

Some species carry particular significance. The Celts saw white butterflies as the souls of dead people. In Scotland, the small tortoiseshell was known as the witch’s butterfly. I don’t know why they thought negatively about a butterfly loved elsewhere.

The complexity of the symbolic associations created around butterflies is interesting in that it shows our suspicion of beauty. Beauty cannot be trusted. It often conceals ugly realities. In the poem Butterflies Rosita Boland writes about landmines in Bosnia “Decorated with butterflies”. Children who touch them become “winged in the act/Gaudy and ephemeral.”

The sinister practice of targeting innocence is powerfully underscored using the butterfly metaphor. Reaching out for the butterflies, the children become butterflies. The terror is stark, especially with the use of beautiful imagery to convey ugly reality.

Other references are more positive. In his remarkable portrait of trench warfare on the western front (1914-1918) Erich Remarque writes about beautiful Brimstone butterflies fluttering around a muddy trench, a sight that lifts the soul of the soldiers after the horrors of the most recent battle. Interestingly, there are no trees or shrubs nearby. The Brimstone habitat has been destroyed by artillery fire.

While the conflict raged, British troops saw butterflies they knew from home only as extreme rarities, like the Camberwell Beauty and Common Swallowtail. These gave joy amid the horror, a juxtaposition that hopefully offered some relief.

Dipping into the ancient world of Greece, one wonders why a society stocked with great thinkers and writers is almost devoid of even passing references to butterflies. Homer (date of life unknown), Hesiod (c. 750-650 BC) and Plato (428/427-348 BC)  have no recorded mention of butterflies although Aristotle does; in 340 BC, he described the metamorphosis of the butterfly from caterpillar to adult butterfly. This silence is at odds with the ancient Greek curiosity and interest in the world in general. Peter Marren (2019) wonders if the Greeks saw the butterfly as trivia. Important things were the subjects of literature. Butterflies didn’t matter. They are beautiful but essentially useless. I have often been asked, “What do they do?” Implicit is the idea that they do nothing and or they mean nothing unless they do something for humans. Geoffrey Chaucer is blunt in his view of their uselessness.

In The Canterbury’s Tales, the host asks the monk to tell another tale:

Sir Monk, no more of this, so God you bless!

Your tale annoys the entire company;

Such talking is not worth a butterfly;

For in it is no sport nor any game.

(The Canterbury’s Tales: The Nun’s Priest’s Prologue lines 14-39: The Host asks the Monk to tell another tale )

Shakespeare is not complimentary either. In King Lear, after Cordelia’s forces are defeated and she and her father King Lear are imprisoned, Lear comforts her:

Lear: No, no, no, no! Come, let’s away to prison: We two alone will sing like birds i’ the cage: When thou dost ask me blessing, I’ll kneel down, And ask of thee forgiveness: so we’ll live, And pray, and sing, and tell old tales, and laugh At gilded butterflies, and hear poor rogues Talk of court news;

(King Lear Act 5, Sc 3, 1-4)

Butterflies are fake; the characters Lear alludes to are the hypocrites in the royal court.

William Wordsworth (1770-1850) was far more positive. He sees the butterfly as a reminder of his younger self and “My father’s family”:

Stay near me – do not take thy flight!

A little longer stay in sight!

Much converse do I find in thee,

Historian of my infancy!

Float near me; do not yet depart!

Dead times revive in thee:

(To a Butterfly lines 1-7)

The second verse is a dip into the past when he and his sister “Emmeline and ITogether chased the butterfly!” He hunted the butterfly with vigour and Emmeline, his gentle sister, was careful not to damage its delicate wings. Wordsworth does not evoke any larger interpretive vision of butterflies. They matter to him because they stir memories of his past.

It is interesting to note that Wordsworth lived in England when butterflies were regarded as wonderful, objects of desire and as species worthy of serious study. Attitudes were changing. People invested their time and money in acquiring specimens and breeding and studying butterflies.

Today butterflies hold a firm position as representing the condition of the natural world. We know they are important indicators of the health of our broader environment. They are less often viewed simply as beautiful but essentially useless; our knowledge of ecology and the key role butterflies play in ecosystems means they are taken seriously. They show the effects of climate change, land use change, the use of chemicals in farming and atmospheric pollution. They indicate when our environment is improving or degrading. In essence, they teach us about ourselves, just as Wordsworth described in 1807.

 

 

 

 

As a species with a large brain and extraordinary imagination, we often believe we can do anything. We landed on the moon, explored Mars, developed answers to diseases that have killed people for thousands of years, and increased human lifespans at an extraordinary rate. In 1900, the average life expectancy in the UK was 48. Today it is 81.92 years. My great-grandfather died at age 31. I can expect to live 51 years longer. We produce enough food to feed 10 billion people. We can, it appears, achieve anything.

Man can be forgiven for hubris. The record of achievement is phenomenal. There is nothing bigger than us. All other life forms appear to be under our control. We are masters of our planet.

But planet Earth is a complex place with systems we interfere with at our peril. A key system that regulates our climate and distributes nutrients is the Atlantic Meridional Overturning Circulation (AMOC).

The AMOC circulates water from north to south and back in a long cycle within the Atlantic Ocean. This circulation brings warmth to various parts of the globe and carries nutrients necessary to sustain ocean life.

The circulation process begins as warm water near the surface moves toward the poles (such as the Gulf Stream in the North Atlantic), where it cools and forms sea ice. As this ice forms, salt is left behind in the ocean water. Due to the large amount of salt in the water, it becomes denser, sinks, and is carried southwards in the depths below. Eventually, the water gets pulled back up towards the surface and warms up in a process called upwelling, completing the cycle.

The entire circulation cycle of the AMOC, and the global conveyor belt, is quite slow. It takes an estimated 1,000 years for a parcel (any given cubic meter) of water to complete its journey along the belt.

This system was turned off during the last Ice Age. Now there is evidence that pre-history may be repeating itself.

Susanne Ditlevsen and her brother Peter Ditlevsen, issued a stark warning in their 2023 paper, “Warning of a forthcoming collapse of the Atlantic meridional overturning circulation”. Their paper predicts a tipping point, to occur in 2057.

The AMOC has only been monitored continuously since 2004 through combined measurements from moored instruments, induced electrical currents in submarine cables and satellite surface measurements. Over the period 2004–2012, a decline in the AMOC has been observed.

The threat to AMOC is climate warming. The rising temperatures are causing ice in the North Atlantic region to melt, adding fresh water to the North Atlantic. This decreases the salt content as the current reaches the North Atlantic. This makes the water less dense. This means the water will eventually not be pushed down (overturning circulation) to the seabed to begin its southward journey, as happens now.  This means the water will not be rewarmed and will not return to the North Atlantic, to bring mild air to Northern Europe, including Ireland.

The Ditlevsens estimate an inaccurate confidence in the stability of AMOC. The  Intergovernmental Panel on Climate Change (IPCC), based on the Climate Model Intercomparison Project (CMIP) model simulations suggest that a full collapse is unlikely within the 21st century.  The UK Met Office agrees with the IPCC that a collapse before 2100 is unlikely. But as our future descendants would say, “That’s no good to us.”

Based on the data used by the Ditlevesens, the tipping point is nigh. 2057 is 33 years hence. While many climate scientists disagree with the Ditlevsens, nobody has been able to prove them wrong.

What are the impacts of a major slowdown in AMOC?

According to the UK Met Office, the impacts of an AMOC collapse are as follows.

An AMOC shutdown would cause cooling of the northern hemisphere, sea level rise in the Atlantic, an overall decrease in precipitation over Europe and North America, and a southwards shift in monsoons in South America and Africa.  These impacts are robust and seen in many models, but their magnitude remains uncertain. Atmospheric circulation over Europe may also change, possibly causing more winter storms in Northern Europe and increasing summer rain around the Mediterranean.  Impacts outside of the Atlantic region are less certain, but could affect Asian monsoons and El Nino. (Met Office, 2019)

René M. van Westen, Michael Klipphuis and Henk A. Dijkstra in their paper Physics-based early warning signal shows that AMOC is on tipping course, published in February this year (2024)  gives a very stark picture of what a collapse in AMOC will bring.

The AMOC collapse dramatically changes the redistribution of heat (and salt) and results in a cooling of the Northern Hemisphere, while the Southern Hemisphere slightly warms. Atmospheric and sea-ice feedbacks, which were not considered in idealized climate models studies, further amplify the AMOC-induced changes, resulting in a very strong and rapid cooling of the European climate with temperature trends of more than 3°C per decade. In comparison with the present-day global mean surface temperature trend (due to climate change) of about 0.2°C per decade, no realistic adaptation measures can deal with such rapid temperature changes under an AMOC collapse. (Westen et al., 2024)

They also mapped the consequences of a collapse. Sea levels in the Atlantic would rise by a metre in some regions, inundating many coastal cities. Wet and dry seasons in the Amazon would flip, potentially pushing the already weakened rainforest past its own tipping point.

Temperatures around the world would fluctuate far more erratically. The southern hemisphere would become warmer. Europe would cool dramatically and have less rainfall. While this might sound appealing compared with the current heating trend, the changes would hit 10 times faster than now, making adaptation almost impossible.

“What surprised us was the rate at which tipping occurs,” said Dr René van Westen of Utrecht University. “It will be devastating.”

There was not yet enough data to say whether this would occur in the next year or in the coming century, but when it happens, the changes are irreversible on human timescales. “We are moving towards [collapse]. That is kind of scary,” Dr van Westen said. “We need to take climate change much more seriously.”

Declines of the magnitude of 3°C per decade point to catastrophe. Our ecosystems, already assaulted by habitat and species loss, and pollution would be altered or destroyed. We will cease to be a major producer of food. Areas of the country might be below water.  The world we know now will change utterly. Is it a question of if, or when?

References

Ditlevsen, P. & Ditlevsen, S. 2023, “Warning of a forthcoming collapse of the Atlantic meridional overturning circulation”, Nature communications, vol. 14, no. 1, pp. 4254-4254.

van Westen, R.M., Kliphuis, M. & Dijkstra, H.A. 2024, “Physics-based early warning signal shows that AMOC is on tipping course”, Science advances, vol. 10, no. 6, pp. eadk1189.

Met Office 2019. Risk Management of climate thresholds and feedbacks: Atlantic Meridional Overturning Circulation Available at https://www.metoffice.gov.uk/weather/learn-about/weather/oceans/amoc (Accessed 15 September 2024)

O’Sullivan, K. (2024) Collapse of Atlantic ocean current could turn Ireland’s climate into Iceland’s The Irish Times 16 February Available at https://www.irishtimes.com/environment/climate-crisis/2024/02/16/ireland-must-prepare-for-atlantic-meridional-overturning-circulation-collapse-ff-senator-warns/

 

 

The latest Irish Butterfly Monitoring Scheme report 2023 (Judge and Lysaght 2023) mentions the six most common butterflies recorded using butterfly transect recording.

1. Meadow Brown 7716
2. Speckled Wood 5678
3. Ringlet 3849
4. Small Tortoiseshell 3582
5. Peacock 2997
6. Green-veined White 2488

While 2023 lacked warm, dry summer weather after the end of June, populations of some species proved quite high. I was thrilled to see a great recovery in Peacock numbers, for example, which were much lower in 2022. The Small Tortoiseshell also featured in thrilling numbers during 2023 in the places I look for butterflies, chiefly south Meath and north-west Kildare.

The figures given above are taken from transects, not from casual recording. Transects are fixed route walks when counts are made each week from 1 April to 30 September or are made five times during this period.

Casual butterfly recording is recording butterflies seen in a location but without necessarily visiting that location regularly and probably not applying a standardised counting methodology. This does not mean that casual recording is not valuable. Casual recording is vital to obtain distributional data meaning it allows us to know where in a country butterflies occur. Furthermore, many casual recorders report their sightings from an area they visit regularly, so results can be broadly similar to those obtained when walking the fixed route used in a transect.

The records on the Butterfly Conservation Ireland record database are a mixture of transect records, records from regularly visited locations and records arising from one-off site visits.

As an imperfect, interim comparison exercise, we compiled the records Butterfly Conservation Ireland received of these six most common species from the beginning of 2024 to the end of August 2024 and ranked them numerically.

Here is what we found.

1. Meadow Brown 2225
2. Ringlet 1632
3. Speckled Wood 642
4. Green-veined White 526
5. Peacock 245
6. Small Tortoiseshell 188

While the Meadow Brown held the top spot, the other five species changed their placings. The crashes in the Peacock and Small Tortoiseshell populations are particularly striking.

The number of Small Tortoiseshell recorded in July 2023 (351) and for the Peacock in August 2023 (881) heavily underline this collapse. August 2023 saw more 72% more Peacock records than the first eight months of 2024. For the Small Tortoiseshell that figure is 46%. A comparison for both species using the full years will show even steeper drops.

We hope to bring you that analysis in our Annual Report 2024.  For the Annual Report 2023, see https://butterflyconservation.ie/wp/butterfly-conservation-ireland-annual-report-2023/

We expect the figures for the Small Tortoiseshell and Speckled Wood to increase appreciably during September, a key month for both but the damage to the Small Tortoiseshell from April to August is too severe for its abundance to come close to last year’s population.

Several consecutive months (July 2023-April 2024, except February 2024) with heavy rainfall is the likeliest cause of the declines. While June and July 2024 had below-average rainfall in most places in Ireland, the temperatures were below average everywhere in July and nearly everywhere in June. In August 2024, the temperature was below average in most areas and rainfall varied widely, with Dublin Airport receiving 50% of its average rainfall, compared with areas in the west of Ireland which saw their wettest August since 1992 (Belmullet) and 1985 (Newport).

Two weather stations had their wettest August on record. These were Malin Head, Co Donegal with 181.3 mm (record length 69 years) and Knock Airport, Co Mayo with 215.4 mm (record length 28 years). The puzzling month is May 2024. Met Eireann reported May 2024 as the warmest on record; however, it was dull and overcast much of the time, with all available monthly sunshine totals below their long-term average. Direct sunshine is important for butterfly and moth larvae. Perhaps this deficiency added to the crisis.

I have yet to see a Small Tortoiseshell in my garden in 2024; I have seen this butterfly in my garden for each of the last 26 years. I hope for a September bailout. We could do with a burst of butterfly joy!

Key References

Judge, M and Lysaght, L. (2024). The Irish Butterfly Monitoring Scheme Newsletter, Issue 16. National Biodiversity Data Centre.

Past weather statements (2024) Met Éireann – The Irish Meteorological Service. Available at: https://www.met.ie/climate/past-weather-statements (Accessed: 03 September 2024).

All photographs J.Harding

One of Europe’s most widespread blue butterflies (absent in Ireland), the Chalkhill Blue Lysandra coridon, a relatively large species of blue which in the male has bright pale ‘chalky’ blue uppersides has been studied for its relationship with ants, its conservation needs, especially in England and its genome. Genome refers to the full complement of DNA in a cell.  DNA contains the information needed for an organism to develop. Humans have 23 pairs of chromosomes in the cell’s nucleus. As is the case for butterflies, half are inherited from each of the parents. The haploid number in a human sex cell is therefore 23; the full complement after the fusion or joining of the chromosomes, the diploid number, is 46.

The Chalkhill Blue, however, does not always conform to this neat formula. From Spain to Bulgaria, the chromosome numbers in Chalkhill Blues range from 87-92 with higher counts predominating in eastern Europe. From southern to northern Europe, the chromosomal range is 87-90. Why has the butterfly added chromosomes as it moved north after the last Ice Age, and while moving east?  Was it adapting to a cooler climate? Typically, an animal contains a fixed number of chromosomes; a butterfly with more or fewer than another butterfly might be a different species.

Does this mean that the ‘Chalkhill Blue’ in England and northern Europe is a separate species from the Chalkhill Blue in Northern Spain? Not necessarily, according to Tom Tolman, author of the Collins Guide to The Butterflies of Britain and Europe, expertly illustrated by Richard Lewington.

Tolman states the change in chromosome numbers from Spain to Bulgaria appears clinal. A cline is a progressive, usually continuous change in one or more traits over a geographical or altitudinal range. An example of a cline in Ireland might be the change in the proportion of brown to blue female Common Blue butterflies. In drier coastal areas in eastern Ireland, most females have brown uppersides. As one moves west, there is a progressive change from brown to blue, with some females in the far west showing very little brown on their uppersides.

No one currently believes these blue and brown Common Blues are separate species. In Scotland, the Common Blue produces one generation a year and maintains this characteristic even when bred in the south of England. It is genetically programmed to produce only one generation but this genetic difference with its southern English cousins does not make it a separate species.

Neither are factors such as appearance always reliable species indicators; the Wood White and Cryptic Wood White are identical but separate species. The most accepted definition of a species is based on whether two individuals can or are willing to mate to produce offspring that are healthy and can reproduce.

This occurs when Chalkhill Blue butterflies with slightly different chromosome numbers pair. The additional unpaired chromosome is excluded. While this might result in the loss of some genetic information, such loss is likely selective and does not prevent the development of viable offspring. Nature finds a way.

There is plenty of confusion concerning the Chalkhill Blue.  Many colour forms confuse taxonomists as to what butterfly they are looking at. Some believe that the butterfly that occurs in central Spain, Lysandra coridon caelestissima (Verity 1921 Type Locality: Central Spain, Albarracin) is a sub-species [i]of the Chalkhill Blue; others say it is a separate species. Tolman (2009) accepts the Macedonian Chalkhill Blue Lysandra phillippi as a separate species. Based on appearance, I find it impossible to separate this butterfly from the Chalkhill Blue in England. The Macedonian Chalkhill Blue uses the same larval foodplant, Horseshoe Vetch and is single-brooded, appearing in July and August, like populations in southern England. However, the Macedonian Chalkhill Blue has a much lower chromosome count, ranging from 20-26; in the Chalkhill Blue, this ranges from 84-92.

Just because the Chalkhill Blue has many more chromosomes than the Macedonian Chalkhill Blue does not mean that there are significant genetic differences. Some genes (DNA sequences on a chromosome) are redundant, persisting as a legacy of evolutionary history. In humans, the appendix is largely believed to be redundant, for example.

Some believe the Chalkhill Blue might be producing new species through fission events. Fission occurs when a single entity divides into two or more parts and the regeneration of those parts to separate entities resembling the original. The object experiencing fission is usually a cell, but the term may also refer to how organisms, bodies, populations, or species split into discrete parts.

A study published in February 2024, Comparative genomics reveals the dynamics of chromosome evolution in Lepidoptera, looked at butterfly genomes and found that most have shown remarkable stability, changing little over 250 million years. However, changes occurred in a few species, including the Chalkhill Blue. Most butterflies hold 28-31 chromosomes, not 90 plus as is often the case in the Chalkhill Blue.

To investigate the dynamics of fission in the Lysandra genus, the study reconstructed the events that gave rise to the genome structures of Chalkhill Blue and the closely related Adonis Blue Lysandra bellargus. Seven pairwise fusions generated a karyotype (full complement of chromosomes) of n = 24 in the last common ancestor of the family Lycaenidae (the coppers, hairstreaks and blues). Fifteen fissions then generated n = 39 in the last common ancestor of Lysandra. Subsequently, Lysandra bellargus underwent six fissions generating n = 45 and Lysandra coridon experienced at least one fission event in 37 of the 39 chromosomes of the Lysandra last common ancestor. An overwhelming majority of the 90 chromosomes in Lysandra coridon mapped to a single Merian element (Merian refers to ancestral linkage groups of modern butterflies and moths) and show conservation of gene order. The few Lysandra coridon chromosomes that contained segments from more than one Merian element derive from the seven fused chromosomes present in the common ancestor of the family Lycaenidae.

The study states that fusion and fission events are rare and very rare respectively and overwhelmingly occurred in just eight of the 32 ancestral linkage groups modern butterflies and moths are derived from. Other species that have undergone such changes are the Large White Pieris brassicae, Green-veined White Artogeia napi, Small White Artogeia rapae, Tinea semifulvella, Hewitson’s Tiger-wing  Melinaea menophilus, Melinaea marsaeus, Black-veined White Aporia crataegi, Lesser Marbled Fritillary Brenthis ino, Winter Moth Operophtera brumata, Brown Scallop Philereme vetulata, Wood White Leptidea sinapis and Lilac Beauty Apeira syringaria.

Of these, the Large White, Green-veined White, Small White, Winter Moth, Brown Scallop, Wood White and Lilac Beauty occur in Ireland. Some believe the Green-veined White is in an active state of evolution while others maintain the variations in this butterfly are influenced by ecological factors. Ecological factors that influence the appearance of a species can include climatic influences such as sunshine and rainfall levels, cloudiness, temperature, and features such as elevation and habitat conditions such as the presence of exposed rock, etc.

However, adaptation to ecological conditions can give rise to new species.

Speciation (the process by which populations evolve to become distinct species) can occur in response to changing conditions, such as a changing climate. Mutations (alterations in the DNA) occur naturally in all populations. Better-adapted mutants thrive while less well-adapted individuals gradually, or suddenly, disappear. Less beneficial traits are bred out by natural selection. This underlines the importance of conserving genetic diversity within species, meaning conserving a species across various habitat types, landscapes and continents.

However, we have seen that most butterfly genomes have remained stable over the past 250 million years. This indicates that Lepidoptera are well designed containing within their genome sufficient resilience to adapt to changing conditions to continue their purpose.

We ought to marvel at this winning design. Butterflies have been on the planet far longer than us. The first modern genera [ii] came into existence during the Paleogene era, between 23-66 million years ago. The oldest known still-existing species is the Ancient Metalmark Voltinia danforthi, from Sonora, Mexico. This butterfly evolved as long as 40-50 million years ago. Homo sapiens emerged about 300,000 years ago (Smithsonian Magazine, 2021).

Our destruction of most of the planet’s natural vegetation is challenging 250 million years of Lepidoptera existence, the continuation of one of the most important animal groups on Earth. We need to adapt rather than reshape the environment to suit ourselves.

Key References

Handwerk, B. (2021). An Evolutionary Timeline of Homo Sapiens. Smithsonian Magazine. Available at: https://www.smithsonianmag.com/science-nature/essential-timeline-understanding-evolution-homo-sapiens-180976807/.

McKie, R. (2024) Startling genome discovery in butterfly project reveals impact of climate change in Europe, The Guardian. Available at: https://www.theguardian.com/environment/article/2024/aug/11/genome-discovery-butterfly-project-impact-climate-change-europe-moths?CMP=share_btn_url (Accessed: 19 August 2024).

Tolman, T. and Lewington, R. (2009) Collins Butterfly Guide. Harper Collins, London.

Wright, C. J., Stevens, L., Mackintosh, A., Lawniczak, M., & Blaxter, M. (2024). Comparative genomics reveals the dynamics of chromosome evolution in Lepidoptera. Nature Ecology & Evolution, 8(4), 777-790. https://doi.org/10.1038/s41559-024-02329-4

 

[i] A subspecies is a population occupying a distinct geographical region, separate from other populations of the same species and having constant and clearly different characters; the subspecies can breed with the populations regarded as the species if they meet.

 

[ii] A genus (plural genera) is the group above species but below family, e.g. species: Common Blue Polyommatus icarus, genus: Polyommatus, family: Lycaenidae)

 

All photographs copyright J. Harding.

Butterfly Declines in 2024

How many times have you noticed the absence of butterflies, bees and other pollinators this summer? Months of dull, windy weather are being blamed. Butterfly Conservation UK, who run their Big Butterfly Count across the UK spanning the last two weeks in July and the first week in August, have reported the lowest butterfly count in the 14 years they ran the survey.

So, it is not an impression, it’s fact. Here is an interesting illustration juxtaposing two counts in one of Ireland’s best butterfly sites in 2023 and 2024.

Michael Gray (19/07/2023)
Essex Skipper 8, Cryptic Wood White 2, Large White 26, Small White 12, Green-veined White 12, Common Blue 6, Holly Blue 2, Red Admiral 76, Painted Lady 22 (magnetized to Wild Thyme), Small Tortoiseshell 8, Peacock 31, Comma 6, Silver-washed Fritillary 9, Dark Green Fritillary 2, Speckled Wood 5, Gatekeeper 39, Meadow Brown 20, Ringlet 20, Small Heath 9, Silver Y abundant seen during my exploration of the Raven Nature Reserve from 10.00 am to 6.00 pm, covering about half the open dunes, all the wood down to the southern point, T 113 262, Raven Nature Reserve, Co. Wexford. A mixture of sun and cloud, 50/50.

Michael Gray (16/07/2024)
Essex Skipper 2, Large White 3, Small White 5, Green-veined White 13, Common Blue 1, Silver-washed Fritillary 5, Speckled Wood 5, Hedge Brown/Gatekeeper 17, Meadow Brown 20, Ringlet 82, Small Heath 11, Six-spot Burnet 4, Silver Y 12, Cinnabar larvae several between 11 am and 5 pm at and near T 116 231, The Raven, Co. Wexford. The weather was warm with intermittent sunny spells.

On 19 July 2023, Michael counted 249 butterflies and 19 butterfly species.

On 16 July 2024, Michael recorded 164 butterflies and 11 butterfly species.

Standing in habitats awash with nectar-bearing blooms in the Burren, I needed to search for butterflies there in June, instead of being surrounded by them, as I have been in years past.

The Influence of Weather on Butterfly Abundance

This shortage is not always easily linked to weather-related events; we had high populations of some species last summer, despite the deluges of July and August 2023. Strong declines in a particular year are not disastrous; butterflies have a high reproductive rate allowing for rapid population recovery when conditions are favourable.

A good year, with warm, dry, sunny weather in important months for larval growth for several species, March, April and June following cold winter weather can yield great results. We had warmer temperatures than usual in March and April in the last two years, but June 2024 was cooler than usual with nearly all mean air temperatures below their long-term average.

The greatest difference between these months was in the weather in June. June 2023 was the warmest June on record, and had less rainfall than the average, allowing the caterpillars of species such as the Peacock, Small Tortoiseshell, Red Admiral and Comma to develop rapidly. Species that fly during June (and May 2023, also very dry) had the weather needed to feed and breed.

Is June the key month for these species? The caterpillars of most butterflies are present in June, varying in their development stage according to species. Is there a sensitive phase in larval development during June for some species? Did the extreme rainfall of July 2023 impact populations flying in 2024? During July 2023, rainfall amounts throughout Ireland were high above the long-term average, ranging from 133% to 300% above the long-term average. Extreme precipitation is the number of days above the 97.5 percentile for rainfall during the life cycle period for a particular species at that particular site. A UK study (McDermott Long et al. 2017) found that extreme precipitation is the most frequent cause of population decline in adult butterflies during the first and second-generation adult life stages.

The same study identified the pupal stage of single-brooded butterflies to be vulnerable to extreme precipitation.  Extreme warmth during winter was found to be damaging to butterflies.  Last winter (December 2023 and January and February 2024) are described by Met Eireann as “mild and wet overall”. The study also found that generalist butterflies (our common, widespread species) suffer more than specialist butterflies from extreme climate events (extreme precipitation, drought, extreme cold and heat).

The larva is the growth stage, and larvae are sensitive to weather conditions, often needing precise ecological conditions, including optimum temperature, insolation, surface geology, vegetation type and vegetation structure, and foodplant quality to develop. Adults of some species will move to find the resources needed for sustenance and reproduction and some species can survive long enough to use occasional good weather to breed and lay eggs. Larvae are much less likely or able to move to avoid bad conditions. However, if adult emergence and breeding are delayed by unsuitable weather, the foodplants may be in suboptimal condition. Declines in foodplant quality might be fatal to the successful development of the caterpillar or might result in less healthy adult butterflies. Observers are drawing attention to the number of dwarf butterflies this year.

Interestingly, most butterflies (31/35) are on the wing in June and July. The monthly average of daytime maximum temperatures, sunshine hours, rainfall and windiness are the most favourable during these months. Thirteen species fly in March and 15 in October. After early October the numbers flying collapses, as the conditions and resources needed to sustain adult activity deteriorate rapidly.

When summer weather is poor the four factors contributing to the favourability index are reduced. However, some woodland butterflies are probably better placed to cope with these downturns, given their more sheltered environs; in this suggestion, I am relying on the record of poor summers not reducing Silver-washed Fritillary populations found the following summer. However, in cold summers the Wood White will produce no second generation to speak of, with pupae from the spring flight overwintering until the following spring. This plasticity enables species to ‘wait’ until conditions are at their best before attempting to reproduce but plasticity is limited. The Wood White pupae must hatch the following spring but have around 10 weeks of spring and early summer (June) to select from.

Perhaps the Silver-washed Fritillary caterpillar enjoys a phenological advantage over other woodland butterflies; its caterpillar feeds from March to early June only. This makes it vulnerable only to poor weather during three months, unlike the Speckled Wood whose larva occurs in most of the year and Wood White which exists in the larval form in May/June and August/September.

A feature that has been noted this year is the appearance of dwarf butterflies. This has been observed in Speckled Wood, Holly Blue, Small Tortoiseshell and Peacock butterflies. This is likely the result of insufficient food for the larva. In short, the food available might have been in short supply, food was unsuitable, or both. Some species can still pupate and produce adults when the larva is insufficiently fed but there might be species less able or unable to do this.

Does poor weather per se explain the shortage of butterflies?

The answer to low figures might lie partly in poor weather in combination with the quality of the habitat and where the habitat is located. In a cold, windy summer, butterflies that use species-rich grassland in highly exposed coastal locations, upland slopes and open areas in the Burren will struggle. In these circumstances, butterflies congregate in the most sheltered areas, making them more vulnerable to predators. Most observers have favourite places to record butterflies, especially those doing transect walks. A population can collapse on one site but not nearby. This year, for example, the Marsh Fritillary was numerous in Lullybeg but numbers were far lower in adjoining Lullymore.  Recorder bias and location bias can distort results.

Therefore, a wider scope is needed to assess population trends. That is why the records sent to Butterfly Conservation Ireland matter. We are receiving evidence from various locations around Ireland to show the population trend of most butterflies is down compared with previous years, especially in the summer months.

The Role of Predators

Another factor in low abundance might be predation levels.  Butterflies have many natural enemies. Many are obvious: birds, frogs, dragonflies, spiders. However, a greater number of predators are obscure. Many parasitic wasp species destroy vast numbers of butterflies and in some years these predators reach a peak that collapses butterfly numbers. This phenomenon has been thoroughly studied in the common brassica-eating whites, the Marsh Fritillary and Holly Blue. In the latter two, the loss can be so high that populations disappear from some sites for years. In landscapes with well-connected suitable habitats, butterflies will return, and populations recover. We might be seeing the peaking of parasite populations for some butterflies dragging numbers down.

Weather is the likeliest cause of 2024 Declines

However, because all butterflies flying in summer appear to be in decline, it appears most likely that a common factor is driving declines. The likeliest is our weather. All months from July 2023 to April 2024 had above-average rainfall except January. As we have seen, extreme rainfall damages populations.

Longterm Declines 2008-2023

There is little doubt that populations have crashed spectacularly in 2024. Looking at the population data for our butterflies during the period 2008 and 2023 tells us that we are seeing sustained declines. The National Biodiversity Data Centre report for 2023 shows that common species that are widespread and well-monitored are in trouble. The Large White (-70%), Small White (-69%), Orange-tip (-65%) and Green-veined White (-82%) are in the ‘strong decline’ category with populations lower than the baseline year 2008.

The strong decline of -82% in the Green-veined White since 2008 is particularly disturbing for this is rated as among Ireland’s most widespread butterflies, recorded in over 86% of Ireland’s 10 km squares. It breeds in wet and humid grassland, vegetated damp ditches, hedgerow margins and marshes, along the banks of waterways, woodland glades and rides and wilder gardens. These habitats are common so one would expect the butterfly to thrive.

However, the Green-veined White is not flourishing in areas away from the direct influence of modern farming. Its distribution in Ireland is probably unchanged but its abundance has reduced. The reasons for the decline of the common white butterflies are unknown but what should create alarm is the fact that the Green-veined White, a widespread butterfly that has many larval foodplants and is not a habitat specialist is undergoing a severe thinning. In a sense, this is more concerning than a rare butterfly being in decline.

A Major Crisis?

Rare species can decline when their habitat, occupying small areas is shrinking or suffering neglect but that does not apply to the widespread Green-veined White or other common whites. We need to consider whether our entire countryside is being degraded. The failure of our landscape to support healthy populations of unfussy, common species must sound the sirens.

Time to worry.

Let us hope that butterfly lover Matthew Oates is correct in his statement, “Never underestimate a caterpillar.”

Key References

Judge, M and Lysaght, L. (2024). The Irish Butterfly Monitoring Scheme Newsletter, Issue 16. National Biodiversity Data Centre.

Long, O.M., Warren, R., Price, J., Brereton, T.M., Botham, M.S. & Franco, A.M.A. 2017, “Sensitivity of UK butterflies to local climatic extremes: which life stages are most at risk?”, The Journal of animal ecology, vol. 86, no. 1, pp. 108-116.