With over 1475 moth species recorded in Ireland, we have a wonderful wealth of species to admire. For every butterfly species, we have 42 moth species. Most moths are strictly nocturnal, and these are rarely found without the correct equipment. Like butterflies, moth species have their specific flight time. Below is a very small selection of the moths flying now. I have included the native breeding plants these species use, underlining the need to grow the correct native herbs and trees in our housing schemes, gardens, parks, motorway embankments, woodlands, hedgerows, grasslands, and everywhere plants are planted.
If you would like to see these moths, join us on our moth morning, on June 26th. See https://butterflyconservation.ie/wp/events-2/
Just a trio to highlight the beauty of bogs. To defend their future, and ours, we need to defend the bogs. That means no more horticultural peat, no more industrial-scale peat mining, no landfills on bogs.
And the benefits? Beautiful wildlife: butterflies, Skylarks, Cuckoos, Curlews, Otters. Clean air: carbon storage. Clean water: flood control. Economic growth: a healthy environment brings tourists to see our landscapes. Education: study how bogs function to stabilize climate, improve water and air quality, and how they function as ecosystems. Recreation: bog walks, rambling, cycling, horse riding, boating.
Free at last! But freedom must be managed with the caution and restraint that characterized our outing but it was so refreshing to be in nature, in great company.
The morning began overcast but mild and the forecast promised sunshine. It kept its word.
Blackcaps and Song Thrushes were sweetly and prominently vocalizing the day’s rapture, and soon the first butterfly, a lovely male Marsh Fritillary, as fresh as the morning, flitted into our ken. Netted then released, he calmed obligingly, wings outstretched, with photo ops for all. What we did not know yet was he was the first of around 100 Marsh Fritillaries (all but one were males) we would see on our ramble, for the sun shone liberally for much of the duration.
Shortly after seeing our first Marsh Fritillary, an erratic flyer in an area of poor fen and wet heath stopped us. A Green Hairstreak, the first I have seen off a bog in Lullymore. Looking around, the presence of Cross-leaved Heath, a breeding plant, provides a potential context.
Next, we entered the “corridor” linking Lullymore and Lullybeg, expertly managed by Pat Wyse over the winter months to bring in light and regenerating heath to an area under encroachment. Here the amazing Narrow-bordered Bee Hawkmoth reigns-all the ones we sighted as pristine as the Marsh Fritillaries. Some amazing close photos were taken-see below. Again, they posed nicely for us; it was warm enough for activity but cool enough to discourage freneticism.
Marsh Fritillaries love this corridor too, having moved in to breed following scrub clearances. As a result, we now have an almost contiguous breeding habitat extending from the Irish Peatland Conservation Council Reserve in Lullymore to BCI’s reserve in Lullybeg. Brimstone egg-laying, with the female contorting her powdery abdomen in what looks like a painful procedure to deposit her precious egg, was observed close-up. Pat’s clearance means more Alder Buckthorns are now available for egg-laying Brimstones, so they can distribute their eggs over more plants, which may relieve predation pressure on the butterfly.
We passed through the corridor into the BCI reserve, looking fairly flowerless and bleached, but soon the colour of multiple Marsh Fritillaries brightened proceedings. I have not seen so many on the reserve on one day for at least a decade. This made for a momentous visit.
Another butterfly that seems to be thriving on the reserve is the Dingy Skipper-we saw at least 20, most of them in good condition. A large female Red Admiral fussed around some Meadowsweet plants, evidently mistaking the dark, wrinkled leaves for Stinging Nettles. Flashes of red revealed Small Coppers, with one tattered female laying on a tiny Sheep’s Sorrel on bare peat.
Cryptic Wood White, never numerous on the reserve, numbered five during our sojourn-a very respectably tally on this site. The southern side of the reserve was our last stop, and there were Marsh Fritillaries throughout-this is a new development-it was hitherto very scarce here. It is days like this that show that our hard work in managing the reserve is working-our resources are yielding tangible conservation results. This is thanks to all our supporters for all your help, both financial and practical.
We spent over three hours enjoying nature on this gentle, lovely day, enjoying everything from the tiny Small Purple-barred moth flitting jaggedly over the Common Milkwort to the mighty Buzzard soaring proprietorially above us.
I, for one, was delighted to be out. Thanks to everyone who took part in our walk, making the day so enjoyable.
Lockdown has been hard on people. Long periods without meeting friends and family, without working face to face with colleagues, without playing sports, and following our hobbies with other people are sorely missed. We need other people. That is how we are made.
One of our compensations is nature’s beauty, needed and appreciated more in our restricted circumstances. Bird song really cheers especially during spring when many species are in full voice. The Blackcap is particularly evocative of spring, having a varied, sweet, and melodious broadcast. He sings throughout the day in spring and well into summer. Gardens, woods, and hedges are occupied by this modest-looking bird, which appears to be thriving. Goldfinches, Linnets, Song Thrushes, Blackbirds, Chiff-chaffs are very vocal right now, often singing at the same time, making separating their songs tricky.
A rarer sound now is the call of the Curlew, a sweet but haunting call, made all the more evocative when heard drifting across a vast expanse of bog, surely our wildest and loneliest looking habitat. A dreamy, melancholic repeated note, there is just something mystical about the call, something that stirs in the soul.
So much rarer now, the species is numbered at around 130 pairs, a catastrophic crash mirroring the mass destruction of our bogs. The plummeting population of the Curlew and other birds are well recorded but many species are declining without our knowledge, silently vanishing, having no voice for us to notice their plight.
The mass decline and extinction of species from many areas is a stark underliner of our loss and mortality. By replacing natural habitats with agricultural grassland, we exchange the profound for the banal, biodiversity with impoverishment. Our sense of place is altered, affecting us culturally and psychologically. Who can sigh with satisfaction after replacing flower-filled limestone grassland with acrylic green sward nibbled to nothing by sheep? Who beams with pleasure when the character is ripped from the countryside? The ‘blanding’ of our landscapes carries on as I write; there is a hideous human drive, it seems, to ‘improve’ land. The outcome is that we are all diminished and have so much less to leave to following generations.
In butterfly terms, many losses do not show up on distribution maps. The maps are often produced at the 10 km resolution, which does not pick up local extinctions. In some of these 10 km squares, a population of a particular species is confined to a single site but the map gives the impression that the species is well represented in that square. A study by Thomas and Avery (1995) showed that maps at the 10 km resolution probably reflect real declines in only the rarest species, whereas declines of species of intermediate rarity may be underestimated by as much as 85%, and population losses of common species are unlikely to be detected at all.
One species that is now locally scarce but is not showing range contraction on butterfly atlases is the Small Heath. For species that are declining strongly, like the Wall Brown, the 10 km maps are showing range contractions. For butterflies like the Small Heath and Small Copper, To obtain a clearer reading of the status of butterflies like the Small Heath and Small Copper, maps with a more detailed level of resolution are needed. If you can help with recording, please send in your records, according to the details here https://butterflyconservation.ie/wp/records/
Why are declines happening?
Recently, a conservationist who carries out site surveys told me that he is seeing “habitat destruction everywhere” he looked. One does not need to look hard to see this depressing situation. Here are just some examples of habitat destruction and some butterfly losses arising.
These are just a few examples of habitat damage. But there are many more, including around our own homes. Spraying chemicals to control “weeds” create damage, and this anti-social behaviour, while not as conspicuous as industrial-scale pollution and habitat loss, damages ecosystems too and says so much about our attitude to nature. Conservation starts at home. Let us all play our part.
Spring has really made its presence felt over the last week, with abundant sunshine bringing nature to life. Birdsong seems constant, with Blackcap, Chiff-chaff, Willow Warbler, Song Thrush pouring their music from scrub and hedges everywhere. The Barn Swallow arrived in early April and the Cuckoo has been heard in Donegal.
The Brimstone is on the wing in its open woods and scrub habitats that contain its breeding plants, Purging Buckthorn and Alder Buckthorn. Orange-tips, emerging later than in recent years, are now flashing their gleaming, high-vis orange tips in bright sunshine while the less showy females already looking for egg-sites. Green-veined Whites are emerging too-a species to watch, given a recent decline. Large Whites and Small Whites are now hatching from their pupae and exiting the gardens where they pupated last autumn. Speckled Woods are out too-less conspicuous than the whites, but can be seen fluttering around grassy scrub and hedge edges edged with wild grasses.
Holly Blue, a much smaller butterfly than any mentioned so far, is highly prominent because their shining lilac-blue gleams in the sun. This active butterfly loves suburban and urban gardens with holly and ivy, the breeding plants for the first and subsequent generations respectively.
Comma, Peacock and Small Tortoiseshell butterflies are found in and around their Stinging Nettles, the food plant for their caterpillars. Males are quite territorial-while the sexes look identical, males will fly after any object thrown in the air, while the females ignore it.
Spring butterflies are at the mercy of the weather. Spring can collapse into winter very suddenly, and when this happens for a prolonged time, spring can be over for these early season fliers. In short, enjoy the Orange-tips, Brimstones and the rest of spring’s insects, two of which are featured below, while they are here!
Brutus: There is a tide in the affairs of men.
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
On such a full sea are we now afloat,
And we must take the current when it serves,
Or lose our ventures.
Julius Caesar, Act 4, Scene 3, 218-224.
An era has ended for Ireland’s state-owned bogs and a new phase is beginning. Bord na Móna’s announcement in late 2020 that all peat cutting has ended on its estate coupled with the Government’s Peatlands Climate Action Scheme (PCAS) announced by the Minister of the Environment, Climate Action and Communications Eamon Ryan on 24 November 2020 marks a new beginning. This Scheme will see the Minister support, via the Climate Action Fund, Bord na Móna in developing a package of measures, for enhanced decommissioning, rehabilitation and restoration of cutaway peatlands, referred to as the Peatlands Climate Action Scheme. The additional costs of the scheme to rehabilitate peatlands are being supported by the Government through the Climate Action Fund, administered by the Department of Environment, Climate and Communications (DECC), while the National Parks and Wildlife Service (NPWS) will act as the Scheme regulator. (Details of the scheme can be found here https://www.gov.ie/en/publication/136a7-bord-na-mona-bog-rehabilitation-scheme/)
Before we get too excited, we need to consider the condition, among other important factors, of the peatlands being rehabilitated. Most of the peatland areas selected (and there are many bogs that have not been added to the scheme) are so severely degraded that it is not possible to restore them to anything resembling their once pristine condition. In short, the restoration of “active raised bog” as described by the European Union Habitats’ Directive Annex I within the foreseeable future is not possible. In fact, the primary objective of the Government scheme is not habitat restoration but to turn carbon-emitting peatlands into carbon sinks to address climate change. This is a worthy objective, especially as the re-wetting is planned to set the peatlands on a trajectory towards the establishment of a mosaic of compatible habitats including wetland, fen, reed swamp, wet woodland, heath, embryonic sphagnum-rich peat-forming communities, scrub and birch woodland communities.
Refinements in the re-wetting measures will be applied where important grassland habitats have developed on parts of the peatlands selected for enhanced decommissioning, rehabilitation and restoration. This is key to protecting important butterfly habitats. Some bogs contain superb grasslands, including orchid-rich grassland one might expect to see in a very different habitat, such as in karst landscape and eskers. Some of the high-quality grasslands are so studded with summer orchids the fragrance is stunning, almost cloying in its concentration. Over this fragrant colour dance bejewelled butterflies like Common Blue, Dark Green Fritillary and Small Copper.
Modern farming has destroyed the vast majority of flower-rich grasslands making the biodiverse grasslands on peat soils the last bastion for many butterflies. Some species that are now unknown from farmland have found refuge in cutaway bogs (peatlands from which most of the peat has been removed). There is, for example, no known viable population of the Dark Green Fritillary butterfly in County Kildare outside the Ballydermot Bog group area.
This area of bogland currently holds among the best butterfly and moth habitats and populations in Ireland. The area holds 25 butterfly species, some of these endangered, and hundreds of moth species, including endangered species. Exceeding an impressive 5,000 hectares, in one large contiguous block, it is the right size for species to move around in the landscape, allowing species to find the best habitats for their needs and avoid genetic bottlenecks which damage a species’ vitality. Butterfly Conservation Ireland’s monitoring of the Marsh Fritillary in the area shows that the species is moving around in the landscape taking advantage of optimum habitat as it develops. We have noted that there is a high level of variability in the wing markings of the Marsh Fritillary butterflies in the region, a clear indication of genetic diversity. In short, the population of this endangered butterfly is healthy here and this must continue.
Once in a Lifetime Opportunity
Peat-cutting has ceased in the state-owned Ballydermot Bog group area. The machinery has fallen silent, and the sounds are now exclusively nature’s voices. Ravens and Whooper Swans in winter, Cuckoos and Willow Warblers and Great-spotted Woodpeckers in spring, grasslands sizzling with grasshoppers and humming with the drone of bees shouldering their way through flowers in summer, followed by Goldfinches, Linnets and Lesser Redpolls delivering their liquid notes throughout autumn as they pick their way through the rich seed harvest.
Flowers bloom from April to October hosting various butterflies, bees, moths and much more according to the season. Vast native birch woods, shrubbery rich in birds, sky-reflecting lakes, ponds, dry and damp calcareous grassland, wet grassland, heath, fens, bogs abound. There is so much for the nature-lover and rambler to enjoy. The varied landscape gives a restless and artistic eye the drama of change to soothe and inspire. The area offers you the freedom to lose yourself.
And look where the area is, on the doorstep of the biggest population of people in Ireland, a wilderness offering exploration, freedom, health and happiness. I once brought a group of underprivileged urban teenagers to these bogs on a fairly dull spring day. After clambering out of the minibus they looked around, bemused. “Where are the shops?” “Where are the paths and street lights?”
I feared a long, long day. But no. They loved every minute of it. “Are we allowed to go here?” There are no walls, boundaries or prohibitions to inhibit freedom. Of course, they jumped in every pond, drain and puddle available, amazed at frog spawn and “water lizards” (newts!) Notorious for their boisterous behaviour, their exuberance was appropriate here, perhaps for the first time.
Why am I telling you this? Because there is so much more to nature and what it has to offer than hitting climate action and Water Framework Directive targets, very important though these things are. Horse riding, walking, running, cycling, picnicking, scientific study for young and all other age groups are available along with tremendous physical and mental wellbeing benefits. And, perhaps above all, the vastness of the space offers great freedom. And all compatible with habitat restoration and nature conservation.
It is time to show vision, to take the opportunity now available. The west of Ireland has five national parks. There is no national park in Ireland’s midlands. Without this landscape-scale protection, the long-term viability of many species in the region is in peril. Butterfly Conservation Ireland, together will all the non-governmental environmental organisations, is calling on the Minister of the Environment, Climate Action and Communications Eamon Ryan, Bord na Móna, Kildare County Council and the National Parks and Wildlife Service to establish a new national park in the Ballydermot Bog group area, for nature, for people, forever.
In the butterfly world, signs of spring are often well concealed and most of the signs that are detectable are subtle and elusive. The glowing colours of the adult butterfly will only be seen later in the season in the case of most of our species so we must look hard for the signs that are available. Below are some of these signs. Let us imagine how these lead to greater glories as warmth returns.
Ireland’s butterfly species operate in a relatively cool climate which presents challenges to these ectotherms, cold-blooded animals whose regulation of body temperature depends on external sources, such as a cool, shaded woodland or direct sunlight or a heated surface such as a mat of dead vegetation, branch or rock. The metabolic activity and physical movement of butterflies are highly influenced by the thermal environment. This article looks at strategies butterflies use to deal with their thermal environment.
The adult butterfly needs to fly to escape enemies, to find food, mates and breeding sites. Efficient flight is only possible when the thoracic musculature, which houses the wing muscles, reaches temperatures in the range of 35-40 Celsius. Biological functions, such as mating, egg development and egg-laying, require certain temperatures (these vary according to the species). Air temperatures in Ireland rarely reach the levels needed so how do our butterflies reach the temperatures required for efficient flight and for the metabolic activities needed to sustain life?
During our butterfly flight periods, all our butterflies deal with thermal challenges. These can be unsuitably hot or unsuitably cool conditions. A way to raise body temperature to enable the butterfly to take flight is wing muscle vibration. This is used by a butterfly during cool weather or when it has roosted in a cool location when it is unable to use external heat sources to warm its flight muscles. Wing muscle vibration, which looks like the butterfly is shivering, allows a butterfly to create enough heat to fly to or from cover but will not allow for sustained flight. The butterfly (or moth) vibrates its wings vigorously until it has created heat by friction that enables it to fly, usually weakly and briefly, to reach a suitable location. In cool, breezy weather this strategy may not work, leaving the immobile butterfly vulnerable to predation and severe weather. Occasionally, early on spring and autumn mornings, stranded butterflies can be found resting in the open on a flower from the day before, covered in dew.
Butterflies are efficient heat seekers, frequenting warm sheltered areas receiving direct sunlight even when these sites contain fewer resources than more open sites. It will be noted that open flower-rich grassland will often have fewer butterflies than expected, while sheltered rides in woodland with fewer nectar resources can hold an abundance of butterflies and other insects. Managers of nature reserves containing open, exposed grassland should be careful to allow some scrub, a resource that enables grassland butterflies to find shelter when the weather is cool, cloudy and windy. When the sun shines, butterflies will move into more open areas. As our climate warms, scrub habitats may become vital for butterflies to escape escalating heat during the hottest times of the day or season.
Butterflies also adopt thermoregulation strategies (regulation of body temperature) that vary according to species, habitat and temperature. The wings are used to regulate temperature, both to raise and reduce the temperature. Most of our butterflies will bask with wings held wide open when they need to increase body temperature. This is known as dorsal basking. When the thorax is coolest, the wings are held fully extended and the extreme edges of the wings are pressed against the surface, often bare soil or rock. This is known as the ‘appression’ posture, proposed in one study as potentially different from dorsal basking. This is often seen used by the Small Tortoiseshell, Peacock, Comma, Red Admiral and Painted Lady-the first three species use this technique frequently on cool, sunny days in early spring. This technique is believed to be the most efficient for increasing thoracic temperature, by trapping warm air radiating from the surface, trapping warm air radiating from the underside of the wings and minimising the flow of cooling air around and under the thorax.
Basking with wings held off the surface in a horizontal posture is used to warm the butterfly when it is cool but slightly warmer than a butterfly applying appression. The butterfly is absorbing heat onto the wings, but experiments with dead butterflies show that only 30% of the wing area closest to the body is used to transfer heat to the thorax. A heating thorax causes the basking butterfly to angle its wings, forming a shallower ‘V’ as the thoracic temperature rises until the butterfly folds its wings, a posture to allow cooler air to circulate around the thorax so the insect can cool down. If it becomes too warm for this thermoregulation strategy to be efficient, the butterfly seeks shade.
Lateral basking is another thermoregulatory mechanism used by some of our butterflies. This involves basking with folded wings where the butterfly perches on a surface and angles its wing surfaces by leaning sideways onto the sun to receive the maximum solar incidence when the insect is too cool. When the butterfly is warming, it starts to correct its posture until perched upright. When the butterfly is too warm it stands head-on to the sun, raising its body off the surface by standing tall. This strategy is used particularly and rather strikingly by the Graying, and less notably by the Large Heath, Small Heath, Green and Purple Hairstreaks and the Brimstone. The Brimstone uses this especially in spring, typically by basking on dry, dead grass clumps. Using this mechanism, it can raise its body temperature to the high 30s Celsius when air temperatures are barely above 13 Celsius.
The other form of thermoregulation used is called reflectance basking. This is used by some of the whites, especially the Large White, Small White, Green-veined White and Orange-tip, although these species will occasionally use dorsal basking when they need to recover a steep loss of body heat. The butterfly perches on a surface, usually a leaf, with wings half-open. It orients its position to receive sunlight onto its wing surfaces. The white wings reflect solar radiation onto the body to increase body temperature. A dusting of dark scales on the wings near the thorax may also play a role in heating the thoracic muscles. When it is too warm, the butterfly shields body tissues from the sun by folding its wings.
A thermoregulation mechanism used by the Brown Hairstreak to avoid over-heating on its sunny, sheltered hedge habitat is orienting its closed wings towards the sun, where its shiny undersides reflect rather than absorb the light. While this appears to be lateral basking, which is used to increase body temperature, this rare butterfly mainly uses dorsal basking to warm itself. Appearances can deceive!
Let us look at how adult butterflies respond to prolonged unsuitable thermal conditions. Migration involves butterflies leaving an area that is becoming unsuitable and moving to a location where their needs are met. It enables butterflies to escape the onset of prolonged unsuitable conditions typically caused by changing temperatures. An example of this strategy is the migratory habits of the Painted Lady, which extends its range progressively from early spring onwards through summer, from North Africa, throughout Europe. This continues until the onset of cold weather when return southwards migration of the species is undertaken by the children, grandchildren and great-grandchildren of the individuals that dispersed northwards earlier in the year.
Another response by adult butterflies to prolonged unsuitable thermal conditions (in Ireland these prolonged conditions consist of low temperatures) is hibernation. This is used by the Brimstone, Small Tortoiseshell, Comma and Peacock butterflies and by several moths, such as the Red-green Carpet, The Herald and Tissue. These species remain dormant until suitable temperatures return.
The next time you are outside looking at butterflies, look at the posture it is adopting. There is nothing casual, accidental or whimsical about the way butterflies perch, they are always doing what they do for a reason. There is a lesson for us in that, but you can decide what that is!
Our temperatures are increasing. All the indications show that all our seasons are warmer, spring is arriving earlier, the growing season is lengthening. How good is this for our butterflies? Here we consider just some of the results observed and ponder potential results that may arise from the ongoing climate warming.
Weather conditions play a major role in the abundance levels of our butterfly populations, while climate change plays a deeper role, influencing abundance and distribution of species. Let us start by looking at our three regular migrants. Three migrant butterfly species are considered to recolonise Ireland each year from southern Europe or North Africa: the Clouded Yellow, Red Admiral and Painted Lady. However, nowadays the Red Admiral is commonly present here during winter, blurring the distinction between resident and visiting species. There are also indications that Clouded Yellow larvae and pupae may be overwintering in warm, sheltered spots. This has been recorded in County Wexford.
We may receive new species that are expanding in response to the warming climate. In August 2013, there was a substantial influx of the Long-tailed Blue, with around 30 individual butterflies recorded, predominantly from south and east coast counties of England. In several cases, eggs or larvae were discovered at the same locations and, subsequently, an autumn ‘home-grown’ generation of Long-tailed Blues emerged across southern England, generating sightings of at least 80 individual butterflies spread across eight counties. Although the occurrence of Long-tailed Blue in the UK in 2013 was unprecedented in abundance and distribution, the species is not able to survive our winters and so permanent colonisation is impossible at present. Amazingly, another almost identical influx of Long-tailed Blue occurred in the summer of 2015, again with substantial local breeding and the emergence of a new generation. Milder winters may allow this very successful butterfly to become established in Ireland.
Another candidate for colonisation is the Swallowtail. The Swallowtail a large and spectacular butterfly that, occurs widely in continental Europe and on many off-shore islands. Sightings of this species have increased in southern England. Two were recorded here in recent years, including one last summer. As a highly mobile butterfly, it can reach our island and may become established here if temperatures continue to increase. The species over-winters as a pupa, which may be able to survive our winters as they warm.
We may also receive the Southern Small White as a new species. Until recently, and as its name suggests, this butterfly was confined to southern and especially south-eastern Europe, but it is now spreading rapidly in a north-westerly direction, at the rate of over 100 km per year. It was first found north of the Alps in France and in Germany in 2008 and has since gradually extended its range and was first sighted in the southern Netherlands in 2015. In 2019 it was reliably recorded near Calais in France. So there is only the matter of the 22 miles of English Channel to cross before it arrives on the UK’s shores.
Of course, it may already be in the UK, just not noticed amongst its cousins. This expanding species is likely to be Ireland’s next new butterfly. It breeds on Candy Tuft Iberis sempervirens, commonly grown in gardens, Rock Candy Tuft Iberis saxatilisand Bladderpod Alyssoides ultriculatum, which are also garden plants. It looks very similar to the resident Small White but can be separated from it by looking at the upperside of the forewings. The black wing-tips extend as far down the leading edge or costa as it does along the outer edge or termen. In the Small White, the black wing-tip extends further down the leading edge or costa. The forewing spots are more square rather than rounded and a thin black line extends from the forewing spot (from the forewing spot closest to the wing-tip in the female which has two forewing spots) to the black wing-tip where this extends down the outer edge (termen). If you think that you have seen this butterfly, send us a photograph!
A butterfly success that is associated with increasing warmth is the Comma, unknown as a breeding resident until it was confirmed breeding here in 2014. It is now well established in the south-east and expanding northwards and westwards. It appears to be a matter of time before it is distributed throughout Ireland. Its larva is a solitary feeder, meaning it needs warmer conditions than larvae that feed in groups that help their fellows to absorb heat, like the caterpillars of the Small Tortoiseshell and Peacock butterflies.
The Peacock butterfly, a resident for as long as records can tell us, has increased in abundance in northern parts of Ireland, where it was much scarcer before the 1990s.
Another success being associated with climate ‘amelioration’ is the Holly Blue butterfly. Until the late 1990s, this was mainly restricted to old woodland in milder coastal areas and was very rare outside these areas. Not only is it found throughout much more of Ireland, but it is also producing more generations than it did. E. S. A . Baynes (1964) considered it was single-brooded in the northern half of Ireland and double-brooded in the southern half. Today it regularly produces two generations in some counties in Northern Ireland and three in southern areas, including along the Dublin coast.
Warmer summers appear to be assisting the Marsh Fritillary butterfly, which is usually highly sedentary, especially in wet, cool summers but it will move beyond its colony in warm, dry summers, which was very evident during 2018. The species exists in many areas in a metapopulation, meaning it moves around in the landscape, repopulating sites lost during poor years. To function in this way, the species needs warm weather. Cold May and June weather can destroy colonies, so earlier springs and warmer summers may be an advantage to this endangered butterfly.
But there is always a ‘but’. Warmer drier summers and milder, wetter winters may damage some species even if these conditions benefit others. Take the example of the Small Blue, an endangered butterfly that breeds on one species plant, Kidney Vetch, that only grows in usually poor, well-drained thin and skeletal soils such as on fixed and eroding sand dunes and limestone grassland. These soils dry quickly after a few weeks of hot, sunny weather and the foodplant often desiccates, leaving it useless for breeding. Even more worrying is rising sea levels that can remove coastal dune habitats that are the main stronghold for this tiny butterfly. This is already happening along the east coast, notably at Portrane in Dublin.
More subtle changes are created by climate warming that challenges the survival of butterflies. Milder, wetter winters and earlier and warmer springs prompt plants to remain green and begin growing earlier. While this appears to be good news for some butterflies, this can prevent larvae of some butterflies from developing at an optimum rate to cut down on losses due to natural predation or may prevent some developing, starving to death on their healthy foodplants.
This paradox of heat-loving butterflies declining under a warming climate can be explained by the need of many butterfly and moth larvae for an abundance of dry, senile plant matter which is used for basking to raise their body temperature, allowing for food digestion. This is extremely important for larvae that resume feeding in early spring when air temperatures are low. This problem may be behind the crisis afflicting the Wall Brown, now in freefall across most of Ireland. It has not been seen in Northern Ireland since 2015 and is missing from most areas where it was present before the mid-1980s. I suspect this issue may be influencing the decline of the Small Heath too, for like the Wall Brown the caterpillars are daytime feeders that bask on dry, non-growing plant matter to digest their green food.
The increasingly rapid growth of the larval foodplants creates a shading effect, decreasing ground temperatures, making basking on dry stalks or bare soil impossible (if bare patches will persist for long enough under moister, warmer conditions) unless the caterpillar moves away from the plant which many larvae are reluctant to do.
The constraints on the larval micro-site temperatures may eventually be overcome if climate warming creates air temperatures that are warm enough to allow the larvae to reach the correct body temperature without the need to bask on dry, warm material. However, this is not certain either. One of the drivers of climate warming is the increased level of Carbon Dioxide. This may be affecting foodplant quality.
This is an interesting area of study, and the body of literature on this topic is increasing. At this stage, the picture emerging is that winners and losers will emerge under a warming climate scenario. A study in Germany by Habel et al. entitled Butterfly community shifts over two centuries that tracked butterflies on a dry calcareous grassland site overlooking the Danube from 1840 to 2013 found that changes in the environment associated with industrialisation and climate change are benefiting habitat generalists, especially those that use nitrogen-loving plants and damaging habitat specialists that use plants that are adapted to a low nutrient environment.
However, in Ireland and Britain, we have seen some species that were generalists or that occurred in a broad range of habitats become specialised on a smaller number of habitat types. To add to the mix, one butterfly in Britain, the Brown Argus, that was a habitat specialist has become adapted to a broader range of habitats, a development attributed to the warming climate which has allowed it to exploit foodplants that previously were unavailable because they grow in habitats that were previously to cool for it.
The story told here is a developing one. We can expect colonisation by some species, and some of our current species breeding at higher altitudes than they do now. These are likely to be habitat generalists that are following their climate envelope. What is the future of our habitat specialists, which are generally much rarer? We certainly need to protect their habitats and we need butterfly records to let us know what is happening. We don’t want to lose the plot of this tale. Send us your records, both your casual records and, if you can give the commitment, monitor the butterflies in your garden.
Here is how to provide these records, which will be published on our website and sent to a national database. Send your butterfly and moth records to us by email at firstname.lastname@example.org.
Let us know: your name/s, date of the find, species found, the life stage/s found, the numbers seen, the location the butterfly/moth was found (e.g., townland name, site name, county), and a six-figure grid reference, including the letter identifying the 100,000-metre grid square in which the location lies (see http://www.gridreference.ie/ or Discovery Series maps) weather conditions and any other interesting comments you wish to provide.
John Smith (14/06/2020)
Small Blue 14, Small Heath 15 at O 254515, Portrane sand dunes, County Dublin. Sunny, light breeze, 18 Celsius.
It will be greatly appreciated if you could send in their records by listing the butterflies observed in the following order:
Small Skipper, Essex Skipper, Dingy Skipper, Common Swallowtail, Wood White, Cryptic Wood White, Clouded Yellow, Brimstone, Large White, Small White, Green-veined White, Orange-tip, Green Hairstreak, Brown Hairstreak, Purple Hairstreak, Small Copper, Small Blue, Common Blue, Holly Blue, Red Admiral, Painted Lady, Small Tortoiseshell, Peacock, Comma, Pearl-bordered Fritillary, Dark Green Fritillary, Silver-washed Fritillary, Marsh Fritillary, Speckled Wood, Wall Brown, Grayling, Hedge Brown/Gatekeeper, Meadow Brown, Ringlet, Small Heath, Large Heath, Monarch.
To count the butterflies in your garden, download our Nation Butterfly Garden Survey form below which explains how to record your garden butterflies. We will send you a report at the end of the year after you send us your survey forms.
The rain, wind and misery of January hang heavy on most people, especially on butterfly lovers, who miss the sunshine and happiness inseparable from butterflies. While we wait for better weather to renew our relationship with nature, it is nice to catch up on some reading. A good backdrop to the coming season is Butterfly Conservation Ireland’s Annual Report 2020, now available under the Report tab on this website. The hard copy of the report is free to members of Butterfly Conservation Ireland and will be posted soon. The report is available to non-members at €15.
We hope you enjoy our report and find plenty to interest you. If you have any question or inquiry don’t hesitate to contact us by email at:
or by post:
Butterfly Conservation Ireland, Butterfly House, Pagestown, Maynooth, County Kildare