Butterfly numbers in freefall as biodiversity decline unfolds at pace
Clockwise from top left; Orange-tip butterfly, peacock butterfly, comma butterfly, and small tortoiseshell butterfly. Pictures: Jesmond Harding
April is when spring wildflowers begin to blossom in quantity, in tune with butterflies and bees emerging for the summer season ahead. The offering up of sweet nectar and protein-rich pollen, just when they’re needed most, is one of the most stunning and finely tuned examples of everyday reciprocity.
In damp meadows and wet, grassy byways across the country, one particularly pretty wildflower appears in abundance during April and May. Lady’s smock, also known as cuckoo flower, has delicately pink tinged white blossoms that look a little like an especially elegant lady’s nightdress.
The name cuckoo flower also makes sense, as these wildflowers fill wet grassy fields and verges just as the cuckoos arrive back from Africa in April, calling out over Irish meadows and pastures for a mate.
Linger a while to look at the cuckoo flowers and you may also see a butterfly called the orange-tipped white. Males are readily recognisable by their white wings and bright orange wing-tips.
These butterflies have spent the past 10 months inside a chitin case, correctly known as a chrysalis, and are emerging now for the first time as winged adults. Once mated, they lay their eggs on the tall stems of cuckoo flowers.
I’ll be eagerly looking out for orange-tips in the coming weeks, albeit with a little anxiety about the stability of their populations.
The most recent figures from the National Biodiversity Data Centre contain the shocking news that the Irish population of these sumptuous orange-tip butterflies has declined by 65% between 2008-2023.
Other white butterflies have shown similar and even more severe declines. During this same time period, the small white has declined by 69%, the large white by 70%, and the green-veined white by 82%.
In the case of the orange-tip, their demise is related to drainage of wet fields across the country, which changes the conditions so that the cuckoo flower can no longer thrive there. When such fields are then reseeded with ryegrass, the eviction of wild bees and butterflies becomes almost complete.
Since the 1980s, species-rich grassland, including meadows and pastures, have been replaced with other, more profitable, activities such as intensively managed dairy herds to produce ever increasing quantities export commodities for international markets. With fewer and fewer and fewer places left for the cuckoo flower to thrive, fewer and fewer orange-tipped white butterflies are able to reproduce.
Similarly, dozens of wild flowers that for centuries have been an integral component of semi-natural grassland habitats are eliminated by intensification, with butterflies suffering the consequences. Wild bees, through this same chain of cause-and-effect, are in freefall too.
Of approximately 100 native wild bee species, more than half have undergone substantial declines in their numbers since 1980 in Ireland, with 40 of these species having declined by more than 50%. The rare and declining bumblebees are generally those associated with open grassland habitats.
Ecologists have been warning for decades about the consequences of loss and degradation of species rich and semi-natural grassland habitats. Every few years, research reports are published documenting rapid downward trends in groups of indicator species, with some headed for collapse.
Yet several I have spoken have been shocked by the severity of what has been witnessed during 2024. Even our commonest brown butterflies plummeted, with the charming and well recognised ringlet declining by 70% and the near ubiquitous and unfussy meadow brown having fallen by 69%.
What is especially eerie is the observations throughout last year that well-known butterfly-rich habitats were bereft of butterflies.
According to Jesmond Harding, conservation officer of Butterfly Conservation Ireland, the absence of butterflies in 2024 has been devastatingly obvious, even in the most important, flower-rich areas in Ireland.
Species that are typically abundant in such areas were thinly represented or marked absent, leaving butterfly watchers bewildered by the dearth of even typically abundant butterflies.
The causes for the current collapse in many, once common, butterfly species include the loss of their habitats and degradation of habitats that remain, along with chemical pollution and climate change.
Some species, like the wall butterfly, may be suffering the impacts of the three factors combined. Wall browns emerge from the middle of April and have long been a familiar sight resting on walls and paths, where they soak up the sun as warmth from above as well as from the warm paths and walls where they like to linger.
Only a few decades ago, this was a common butterfly, but today it is scarce, confined to small number of coastal sites and now classified as endangered.
Butterflies and wild bees are two examples of how biodiversity decline is unfolding at pace across the Irish countryside. These species groups are considered ‘indicator species’ — species that can be readily monitored and represent trends in other, harder to monitor, species groups.
All indicator trends are now telling us with no uncertainty that grasslands habitats are being obliterated, collapsing under the pressure of ever greater intensification of land use, as greater profit-serving commodities replace traditional agricultural land uses and associated semi-natural, wildlife rich habitat types.
Widespread awareness of the consequences is not new. It is well known that this is happening, yet the policies that support ongoing habitat loss and degradation continue, albeit with some offerings for the least inconvenient of conservation measures.
Other invertebrates such as moths, hoverflies and grasshoppers — all dependant on species-rich and semi-natural grassland habitat too — in turn support the larger feathered and furry beings who depend on a good supply of invertebrate dinners. The Irish countryside is becoming increasingly inhospitable to all components of wild food webs.
Continuing downward trends are not inevitable. We already know how to reverse these trends, with conservation initiatives demonstrating consistently positive results where carried out with sufficient care. According to Harding, the key obstacle is the “profound societal change” that is needed to ease pressure and implement conservation.
- A deeper look of the threats facing Ireland’s butterflies and how to help can be found in Jesmond Harding’s book, , available in selected bookshops and from Jesmond (jesmondmharding@gmail.com).
- Additionally, will be launched on May 2 at the Royal Irish Academy.
