Despite the fact that hedgehogs are not native to North America and have not (yet) colonized the New World, we still have a special place in our hearts for the spiky little nuzzle-bunnies, whose images adorn everything, including pajamas, scarves, purses and mittens. But in the UK, where hedgehogs literally run wild, the little mammals aren’t feeling the love. Damian Carrington at The Guardian reports that in the last 20 years, hedgehog numbers have dropped an astonishing 66 percent. And they’re not alone. About 20 percent of British mammals are at a high risk of extirpation or extinction and others have experienced large population drops.

The comprehensive study was commissioned by the UK government and looked at 1.5 million sightings of Britain’s 58 mammal species collected by volunteers and citizen scientists and also incorporated data from 500 published studies. The data shows that, while five species—most of them invasive like gray squirrels and muntjac deer—have expanded their range over the last two decades, many others are in steep decline, and some should be considered critically endangered. According to a press release, the red squirrel, Scottish wildcat and grey long-eared bat are particularly threatened. Just one greater mouse-eared bat is known to survive in the UK and the native black rat may be locally extinct, pushed over the edge by the invasive brown rat. The water vole has also seen a two-thirds decline.

“We have almost been sleepwalking,” Fiona Mathews of the University of Sussex and chair of The Mammal Society, which produced the report, tells Carrington. “This is happening on our own doorstep, so it falls upon all of us to try and do what we can to ensure that our threatened species do not go the way of the lynx, wolf and elk and disappear from our shores forever.”

There are several drivers for the mammal declines. The introduction of invasive species that outcompete or spread disease to native animals is a big problem. Road deaths also take a toll as does pesticide use. According to previous studies, hedgehogs are suffering because people in urban and suburban areas keep their lawns and gardens too tidy—the animals need overgrown bushes, leaf litter and other habitat to survive. In rural areas, increased use of pesticides is killing off the insects the hedgies nibble on. “We are concerned about the lack of food in sterile fields where lots of pesticides and chemicals are used – there are also larger scale farms so there are less hedgerows for hedgehogs to use,” Fay Vass, head of the British Hedgehog Preservation Society, tells Josh Gabbatiss at The Independent.

There are some bright spots in the study. The population of animals like polecats, pine martens and badgers have sprung back, now that they are not longer widely trapped or killed for being pests. And the good news is that globally, many of these species are doing just fine. But of course the UK is not the only place with tidy lawns in urban areas and pesticides in rural areas, so some of the species may be suffering elsewhere in their ranges as well. And in the press release, the researchers say there is insufficient data on many animals and others may be suffering population drops not reflected in the dataset. The Mammal Society hopes to rectify that and recently launched the Mammal Mapper app, which allows citizen scientists to input data about the mammals they observe in their day-to-day lives.

Mathews tells Carrington that saving, and hopefully restoring, mammal populations will require new government policies, like the overhaul of subsidies which reward the amount of land under cultivation instead of focusing on productivity or sustainability. It also means programs to get invasive species under control. As Brexit looms, the researchers says the UK needs to make sure it maintains the EU's level of protections for endangered species as well.

In the meantime, Darren Tansley of the Essex Wildlife Trust tells Gabbatiss that there’s plenty citizens can do on their own. “So often we see green space in housing estates and developments but if it’s a mown flat lawn it’s of no use to nature conservation at all,” he says. “You’ve got to have space for untidy nature to exist.”

Study lead author Mathews agrees that communities and landowners need to leave marginal wild spaces like hedgerows and railway embankments alone. “We need to stop thinking of wildlife as being something that happens somewhere else and we just put a [protected area] ring around it,” she says.