The swallowtail, Britain’s biggest butterfly, last year had its worst summer since scientific counting began in 1976. What followed was potentially more catastrophic: the deepest and longest winter floods in living memory across the Norfolk Broads, which is the only place where this spectacular insect still breeds.
The swallowtail fixes its chrysalis low down on reed stems and there were fears that many would perish if submerged in flood water.
So, two cheers: the adult swallowtail has emerged once again, quite early this year, and is flying at hotspots including Strumpshaw Fen and Hickling nature reserve.
It is too early to know if numbers will be even lower than 2023, when only 81 were recorded in scientific counts, but the swallowtail is now very vulnerable.
As the climate crisis causes more Broadland flooding and salination, new sites are needed for the swallowtail’s food plant, milk parsley, which dies in salty water. This year the RSPB is scattering milk parsley seeds in new, less flood-prone locations, hoping to create more climate-resilient homes for the swallowtail.
It sounds simple, but while this rather neurotic, short-lived perennial plant germinates easily, it has high mortality in its first year (probably grazed by deer and rodents). “There are decades of work to do to get ready for these climatic challenges,” said Tim Strudwick, of the RSPB.
