4 minute read
Life on our reserves How we found a jewel of a beetle at WWT Welney
LIFE ON OUR RESERVES
WWT cares for more than 3,000 hectares of wetland habitat in the UK. Thanks to sensitive management and your support, our reserves teem with wildlife. Dominic Couzens discovers some of the ways we nurture these special places for you to enjoy
Here be treasure
also suggests that this treasure has been hiding in plain sight all along.
Having such a new rarity in your care adds extra responsibility. “Now that we have found this small colony of tansy beetles,” says Leigh, “the team at Welney are continuing the work of the invertebrate specialists to carefully manage the expansion of their range.”
It’s clear that the species is vulnerable to large-scale changes, such as grazing or wide-scale coppicing. “So there are no cows allowed,” says Leigh. “We’ve found this beetle along riverbanks with a good mix of light and shade, glorious messy marginal habitat with tall herbs and scattered osiers (a type of willow tree). So, rather than clear-fell any patch of osiers, we carefully manage a handful of 50-metre linear blocks along a 2km stretch, by cutting the trees close to the
Where do you find treasure? It’s rarely in glamorous places, and more often in unexpected ones. Well, everyone was certainly surprised when, during a routine survey of WWT Welney’s outer reaches in 2018, we found treasure in beetle form.
The tansy beetle Chrysolina graminis is a completely new record for the reserve. Not only is this species simply stunning to look at, with a brilliant, jewel-like iridescent green body flashed with a purple lustre, it is also very rare. Until that moment, the species had been known from only two other sites in the UK.
Instead, the beetles were feeding on water mint, purple loosestrife and marsh woundwort, which are abundant in the ditches at this huge site. “If this population doesn’t feed on tansy, it could mean the species has also been overlooked elsewhere,” Leigh points out.
The only other populations in Britain are along the River Ouse in Yorkshire, where the beetle is reasonably abundant, and at Woodwalton Fen in Cambridgeshire. The latter population was rediscovered in 2014 after an absence of 40 years, which
We clear the osiers in small blocks to provide varied conditions for the beetles and many other wetland species “This beautiful beetle is about 10mm long, and iridescent green with stripes of red and gold – it is lovely to see,” said Centre Manager Leigh Marshall
The holly-leaved or spiny naiad is a nationally vulnerable aquatic herb
base. This gives a balance of wild areas and managed areas. We hope that opening up these areas of scrub may increase numbers and help the beetles become established.”
Welney is carefully managed to support a wide range of wildlife, especially breeding waders. “So we have to balance the needs of everything,” continues Leigh. “The tansy beetle is protected by law, but so are our other species. We want to create and enhance wild habitats, but we must make sure we don’t impact anything else in the process.”
I wonder if Leigh loses sleep over trying to look after so many fragile things at Welney. But he assures me it’s more a case of sheer wonder. “I can hardly believe that, over the winter, the beetles’ habitat is under three metres of water. Presumably, the adults survive buried down there somewhere. Nature is simply incredible.”
Andy Brown/WWT
Spiny surprise at Arundel
We have no idea where it came from,” says Suzi Lanaway, Reserve Manager at WWT Arundel. “We are mystified.”
The species surprising everyone is the holly-leaved naiad, which sounds like an alien out of Doctor Who but is actually a native aquatic plant. This is no ordinary plant, it’s an extreme rarity and on the Red List of Threatened Species. Prior to discovery at Arundel the plant had only been recorded in the Norfolk Broads.
“We found the naiad in a freshwater lake on the reserve,” remarks Suzi. “This is where we take visitors out for gentle boat cruises that are much loved by children and families. They were floating past one of the rarest plants in Britain.”
There was no need to worry. Within months of its discovery in 2015, the holly-leaved naiad had become the dominant plant in this freshwater area of the reserve. More recently, it has established in another large pond and in one of the connecting ditches. In 2019, it was found at another location, this time in East Sussex.
Water plants are not the most glamorous of organisms, and don’t receive the attention they deserve. “It’s great to have the naiad here. It provides wonderful cover for fish, which suits our fish-eating birds very well,” says Suzi. “After its initial surge, it has reached a healthy equilibrium with the other aquatic plants.”
Fortunately, the team needs only to make sure that water quality remains good to keep the naiad happy. “We’re lucky at Arundel to have chalk-filtered water, so botanically it’s a very species-rich habitat,” explains Suzi.
There’s no doubt about that – and since 2015 its richness has been enhanced by one rare and intriguing plant.
