Boosting what we know about British mammals
Researchers appeal to wildlife-lovers to fill huge gaps in our knowledge of UK’s mammals.
More than 20 years after the last detailed assessment of Britain’s terrestrial mammals, a major study has revealed large population declines in many species – and many inconsistencies in what we know.
The new survey, Britain’s Mammals 2018, was carried out by The Mammal Society. Previously, the ‘go-to’ source for information about wild British mammals was a 1995 review, long considered out of date. “The data we had been relying on was terribly old,” says Prof Fiona Mathews, chair of The Mammal Society.
One of the report’s innovations is a ‘Red List’ threat-ranking system using IUCN criteria, similar to the one for birds. It classes three mammals as Critically Endangered: the wildcat, black rat (which may already be extinct) and greater mouse-eared bat (of which a single male survives). Eighteen others are judged at risk in all or part of their British range.
To estimate species distributions and population sizes, a lot of informed guesswork and extrapolation was needed, Mathews admits. Citing bats as an example, she says: “We really don’t know much about them.” For two-thirds of British bat species, population trends remain unknown.
For pygmy shrews, among the most abundant mammals, the report’s population estimate is 1–6 million. “That is a huge potential range, which is unacceptable,” Mathews says. “With 30 out of the 58 species we looked at, we can’t tell you what has happened to their distribution.” By contrast, the hedgehog is our best-recorded species, “because people make an effort to share their sightings.”
According to Mathews, part of the problem is that many mammals – unlike the hedgehog, water vole and hazel dormouse – lack formal recording schemes. “We’re schizophrenic in our attitudes to wildlife. We don’t like mice. Many people don’t like mustelids or bats.”
“People don’t go mammal-watching in quite the same way as they watch birds,” adds Prof John Gurnell, a former Mammal Society council member. “Often you are just looking for signs, though camera-traps are now changing this.” To boost the low reporting rate of mammals and help plug the gaps in our patchy knowledge, the Mammal Society has launched a free app, Mammal Tracker, so we can all help. BH