TThe swallowtail butterfly is Britain’s largest and most spectacular butterfly. Most of Britain’s butterflies are small and brown, as they have adapted to survive the harsh, cold, wet and temperamental summers.
But with tiger-like stripes, dashes of iridescent blue and red, and a dapper tail, this amazing animal It looks like it has escaped from a tropical butterfly house.
Ironically, it’s more British than most nominations for British Invertebrate of the Year. As a small offshoot of continental Europe, Britain has relatively few endemic species that are unique to the country. However, as the last part of the scientific name, Swallowtail Britannicusit was revealed that this swallowtail is a subspecies endemic to the UK.
The swallowtail butterfly represents the evolutionary movement of the Anthropocene. This happens when much of their habitat is destroyed and the caterpillar becomes isolated in small wetlands with the only plant it eats (milk parsley).
This large, powerful butterfly is naturally mobile and can fly fast. Like all butterflies, the largest and strongest may choose to fly away from home in search of new habitats.
They venture far, flying over arable fields and drained and constructed wetlands. And what do they find? Nothing. There is no suitable habitat. There is no future.
The only butterflies that survive are smaller, weaker specimens that stick close to home and do not fly very far. Over the years, natural selection has favored this choice, so the British swallowtail is smaller and more slender than its hardy continental counterpart. (The colors are also darker, probably because the conditions here are cooler.)
Currently, the British swallowtail can only be found in the Norfolk Lakes region, the UK’s largest freshwater wetland. But the species faces challenges. Last year’s count was the lowest since scientific monitoring began in 1976. In recent years, the number of breeding sites has decreased from more than 20 to just 16.
Edible milk parsley plants are infected with disease. But most seriously, freshwater areas are at risk from the climate crisis. Sea levels are rising, the east coast is eroding, and more and more salt water is entering and flooding the Broad Islands.
Saline will kill milk parsley. Broads are unlikely to survive in freshwater form much beyond this century. If we don’t provide it, the swallowtail won’t be able to find other suitable habitat.
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Therefore, we need to act to save this species. They require extensive wetlands to survive. great fen project That might be possible near Cambridge, but Swallowtail needs more than that.
There’s another irony. As the British subspecies becomes extinct, global warming is increasingly pushing the continental subspecies of the same species across the Channel to the southern coast. This swallowtail can still be propagated through wild carrots, fennel, and other seeds. It breeds in England in the summer.
Will you fly north and come across a British swallowtail stranded in the Norfolk Lakes region? Will the two subspecies interbreed? Will the modified variants flourish again? Change is coming.
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Welcome to the Guardian’s Invertebrate of the Year competition! Every day from April 2nd to April 12th, we’ll profile one of the amazing invertebrates that live in and around the UK. What invertebrates do you think should be included here? And at midnight on Friday, April 12th, voting will begin for our favorite invertebrate of the moment, and the winner will be announced on Monday, April 15th.
