Last winter Natural England reserve managers Chris Hainsworth and Mike Taylor could be found operating a rotovator at Cavenham Heath nature reserve to the north-west of Bury St Edmunds.
Their aim was to disturb the surface soil and create patches of broken ground across the 200-odd hectares of the site. It’s a task they plan to repeat again this winter.
Typically, this job would not be part of their remit. It would be left to the large rabbit population that has called this area home for over 1,000 years to scratch, burrow and nibble away at the heathland. This activity over many centuries has created a habitat that rare species, such as the stone-curlew and numerous invertebrates and plants, now depend on for their continued survival in East Anglia.
Species that favour, and in some cases are completely reliant on, the bare and disturbed ground in Breckland are the scarab beetle, the brush-thighed seed-eater beetle and the grey carpet moth, whose caterpillars feed on flixweed – a plant of arable margins and other disturbed ground.
Rare plants like perennial knawel, Spanish catchfly and spring speedwell also do well here.
But a drastic drop in rabbit numbers – believed to have been caused by a condition known as rabbit haemorrhagic disease (RHD) – means at the moment human intervention is the only way of maintaining this extraordinary environment until, hopefully, rabbit numbers pick up.
The decline in the rabbit population at Cavenham Heath has been astounding. Mike has kept comprehensive records at the site for 18 years, during which time mid-2009 was a high point with over 1,000 rabbits counted. Their number has been in slow decline since but the crash came in late 2015, when only 13 rabbits were spotted. Numbers remain very low at present with 22 rabbits having been seen on the last count.
“It’s our job to manage the reserve to the highest level we possibly can and this fall in rabbit numbers is a setback,” said Mike.
“It is concerning, but everything is cyclical in nature and in the long-term we hope rabbit numbers will recover.”
A drop in rabbit numbers has also been reported at nearby Norfolk Wildlife Trust reserves at Weeting Heath and East Wretham Heath, while the rabbit population across the wider UK has been similarly affected.
The British Trust for Ornithology (BTO), which, aside from its well-known and highly acclaimed bird research also conducts counts of some of the UK’s most common mammals, has recorded a 61% drop in rabbit numbers across the UK between 1995 and 2016 although it says “the drivers behind this decline are unknown”.
Dr Diana Bell, a conservation biologist and senior lecturer at the University of East Anglia (UEA) says the rabbit decline in the Brecks is almost certainly linked to the advent of rabbit haemorrhagic disease (RHD), also known as viral haemorrhagic disease (VHD), which is a highly infectious and often fatal sickness that affects both wild and domestic rabbits.
As part of her research work, Dr Bell has been studying a wild rabbit population that lives on the UEA campus for over 20 years. Several years ago she saw this population go through a similar crash in numbers.
“It went from bunny heaven to a desert,” she said.
Dr Bell says RHD is believed to have originated from China before spreading to Europe and propagating in large commercial rabbit farms on the Continent. The original strain, she says, hit rabbit numbers in the 1990s, and could be easily diagnosed as dead rabbits were found with blood coming from their nose. But in recent years, a second strain, RHDv2, has been identified which leaves its victims with no outward sign of infection. Many rabbits die in their burrows where the disease can spread easily.
Not since the devastating impact of myxomatosis in the 1950s has the UK rabbit population been so badly affected.
But work is under way to help the rabbit population recover from this crash.
As part of a project called Shifting Sands – an initiative financed by the Heritage Lottery Fund to preserve and manage the Brecks – Natural England keystone species officer Zosia Ladds has been appointed to enhance the habitat for rabbits in the area.
Her work includes overseeing the mowing of grass to make it easier for rabbits to burrow down; creating turf banks that rabbits like to make their home in and piling up brush wood, so they can develop warrens under cover, safe from predators.
“We are rolling out a number of things to see which ones are most helpful to the rabbits,” said Zosia.
“It’s not practical to go round and vaccinate every rabbit, but what we can do is improve the habitat and increase the predator cover to help the healthy rabbit population recover as best as possible.”
The RSPB’s stone-curlew project officer for Eastern England, Tim Cowan, is in no doubt that a restored rabbit population in the Brecks is crucial for the future well-being of one of the region’s iconic birds.
He said: “Stone-curlews need bare patches to put their eggs on – they don’t lay within vegetation, but make a scrape in the bare ground. They also aren’t adapted to moving through dense vegetation and like heathland as it offers good visibility, so they can see what’s coming.
“Sheep are good at keeping grass down but they don’t graze down as tightly as rabbits or create the mosaic of bare ground we need.”
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