In a remarkable conservation success, the UK’s fen raft spider (Dolomedes plantarius), once teetering on the brink of extinction, has experienced a significant resurgence. These impressive arachnids, with leg spans reaching up to 7 centimeters—comparable to the size of a human hand—are now flourishing in their wetland habitats.
Fifteen years ago, the future of the fen raft spider was uncertain due to extensive habitat loss. Recognizing the urgency, conservationists from organizations such as Chester Zoo and the Royal Society for the Protection of Birds (RSPB) initiated a dedicated breeding and habitat restoration program. This involved hand-rearing spiderlings in controlled environments to protect them from cannibalism and other threats. Once matured, these spiders were reintroduced into carefully restored wetland areas.
As of 2024, these efforts have culminated in a thriving population, with over 10,000 breeding females recorded across the UK. This resurgence is particularly notable in regions like the Norfolk and Suffolk Broads, where the spiders play a crucial role in maintaining aquatic ecosystem balance by preying on various invertebrates and even small fish.
Tim Strudwick, site manager for RSPB Mid Yare nature reserves, expressed pride in the project’s success, highlighting the spiders’ importance in preserving the rich biodiversity of the grazing marsh ditches. Despite their formidable appearance, fen raft spiders are harmless to humans and are essential components of their natural habitats.
This achievement underscores the impact of targeted conservation initiatives and habitat restoration in reviving endangered species. The collaborative efforts of wildlife organizations and dedicated conservationists have not only saved the fen raft spider from extinction but have also enriched the UK’s natural heritage.