Glowworms have returned to a North Yorkshire nature reserve after more than 100 years, following a conservation project that began with larvae being raised in a Bristol garden shed. The first glowing females have now been recorded at Nosterfield nature reserve, providing an early sign that the reintroduction of the endangered beetles is progressing. Volunteers from the Lower Ure Conservation Trust counted up to 12 glowing females over several weeks this summer, two years after hundreds of captive-reared larvae were released at the site. Independent ecologist Pete Cooper, who led the breeding work, told The Guardian, “It’s a really great first indicator of initial success.” The project began with a small number of glowworms collected from an authorised local donor site. Cooper bred them in captivity and reared their larvae in Bristol. Further releases are planned, with 1,900 more larvae due to be introduced at Nosterfield later this year.
First glowing females show the glowworms are back
Volunteers from the Lower Ure Conservation Trust counted as many as 12 glowing females over successive weeks this summer. The observations provided an early indication that the released larvae had survived and completed their development at the reserve. Female glowworms are flightless and use their bioluminescent glow to attract males, which have weaker flight capabilities and do not produce the same visible light.For Cooper, who has worked on breeding and releasing glowworms for six years without being part of the project, the sightings represented an important stage in the reintroduction. Cooper added that the sightings showed that “glowworms can live out their full life cycle at this site”, citing the availability of food and for mating as signs that the reserve can support the species.
Nosterfield was once home to many glowworms
Historical records show that glowworms were once present in Nosterfield in large numbers. In 1909, writer Edmund Bogg described the insects as being “wont to hang out their fieldstar lamps … as if lit by the hands of fairy folk”. Their disappearance from Nosterfield followed quarrying, while glowworms have also declined elsewhere across Britain.The source identifies several factors behind the wider decline, including more intensive farming, development and electric lighting. The loss of rough and varied grassland has also affected the habitats the beetles need. At Nosterfield, the Lower Ure Conservation Trust began restoring former quarry land after purchasing its first 72 acres of disused quarry in 1997. The area has gradually been converted into species-rich wetland and grassland on magnesian limestone, with the charity eventually expected to manage almost 600 acres for wildlife.
Project will release 1,900 more glowworm larvae
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The project is continuing beyond the first sightings. With assistance from volunteers at Westbury Wildlife Park Foundation, Cooper has bred another 1,900 glowworm larvae, which are due to be released at Nosterfield later this year. The Lower Ure Conservation Trust has also worked with volunteers to adjust habitat management and monitor the glowworms as they emerge.The reserve’s director, Simon Warwick, credited Cooper and the volunteers involved in the project. He said the return of the species reflected “the raw passion and enthusiasm” of Cooper and the contribution of the 80 volunteers working at the nature reserve. Warwick also said the glowworms were “incredibly rare in the region” and that volunteers were excited by their return. Cooper said the reserve’s population would not be confirmed as self-sustaining until 2030, when offspring from this year’s wild adults are expected to reach maturity.
