Wildlife experts from Buglife and Natural England, along with South East Water’s environment team, are hopping with happiness after discovering Wart-biter crickets at the water company’s site at Deep Dean, near Lullington after an absence of nearly 40 years.
The Wart-biter is a spectacular species – which gets its name from the ancient Swedish medical practice of using them to eat skin warts. Once found across southern England, Wart-biter numbers have declined as a result of habitat destruction, loss of suitable grassland and unsuitable grazing regimes. They are considered to be endangered in the UK and only found at five sites in southern England, three of which are in Sussex.
Thanks to a working group led by Natural England, this rare species of cricket has been reintroduced into a carefully created habitat around Deep Dean Water Treatment Works. It has taken more than 20 years to make sure the site is suitable for the crickets. Wart-biters need a particular kind of habitat which includes bare ground, short turf, wildflowers and taller clumps of grass.
Over the past three years, experts and volunteers from Buglife, Natural England, South East Water, South Downs National Park and ZSL (Zoological Society of London) have been carefully relocating Wart-biters from a donor site in Sussex to Deep Dean. A total of 121 adult Wart-biters, including females laden with eggs, were released at Deep Dean in late summer 2015 and 2016.
Females lay single eggs in bare soil close to clumps of grass. These remain dormant for at least two years before hatching in mid-spring. Once hatched Wart-biter nymphs go through seven instar stages before reaching maturity. Adults are active between July-September, when the males can be heard stridulating to advertise for a mate.
Dr Sarah Henshall, Buglife’s Lead Invertebrate Ecologist said, “We could not believe our eyes when we found two adult Wart-biters at Deep Dean on our first monitoring visit in June. These are the progeny of adults released in 2015. Wart-biters are fussy creatures and finding adults so early on indicates the high quality of the habitat at Deep Dean. We will continue to carefully monitor the population and habitat at the site to ensure the Wart-biters are thriving.”
South East Water’s Head of Environment, Emma Goddard said, “We are absolutely delighted that the habitat we have created at Deep Dean is proving to be perfect for Wart-biters with the exciting discovery of recently hatched adults at the site! This project has involved a huge amount of hard work, commitment and investment over more than 20 years to get to this point. We are honoured to be able to play host to such a prestigious project and delighted that our site is playing such a crucial part in saving the cricket from the very real prospect of extinction.”
South East Water’s Deep Dean site was identified as a suitable place for the Wart-biter to thrive because the land has been carefully managed for more than 100 years to protect water quality in the underground aquifer. This means the land has been kept free from pesticides and chemicals, which has also allowed rare chalk grassland to flourish in the right conditions.
In 1953, Deep Dean was designated a Site of Special Scientific Interest (SSSI) for Wart-biters, but sadly they disappeared during the 1970s. By the late 1980s the site had become overgrown with brambles and scrub. The water company’s environment team recognised the opportunity to manage Deep Dean through a programme of grazing and scrub control with the intention of restoring the chalk grassland and encouraging rare insects and plants to flourish. The company worked with local farmers, Natural England and volunteers from the South Downs National Park to create the necessary environment and conditions.
Natural England’s Senior Invertebrate Specialist, Jon Curson said, “All the hard work of clearing bushes and young trees has paid off - the habitat is now ideal for Wart-biters. This reintroduction forms part of Natural England’s Species Recovery Programme to increase the population of Wart-biters. It is a real team effort between Natural England, Buglife and South East Water. Deep Dean is a key site in securing the future survival of Wart-biters in England.”
ZSL (Zoological Society of London) are assisting the project by undertaking pre- and post-release health checks on the crickets to make sure they are healthy.
Dr Tony Sainsbury from ZSL (Zoological Society of London) said, “The emergence of the first healthy Wart-biter crickets at Deep Dean is a positive step towards the establishment of a new population of this rare species in England. Continued vigilant biosecurity and health surveillance is needed to support these early encouraging signs.”
The reintroduction work continues this year with a further 40-60 Wart-biters being released at Deep Dean over the summer. Long term monitoring of the introduced population will be vital to understand how the population is doing and to ensure the habitat remains favourable for them. It is hoped the reintroduced Wart-biter crickets will once again thrive at this very special site.
The following video has kindly been shared with Eastbourne Buzz by South East Water: