Crabs, badgers and scores of dragonfly wings will be among the fancy dress worn by thousands of people joining more than 350 environmental groups marching through London on Saturday to demand the next government does not “recklessly” ignore the nature crisis. For the first time, mainstream organisations including the National Trust and the RSPB will stand beside hunt saboteurs and direct action activists in the Restore Nature Now march, as campaigners call on the next government to take “bold” steps to tackle the biodiversity crisis. The naturalist Chris Packham, who proposed the march and has led the coalition of green charities taking part, said political parties’ lack of “substantial promises” in the election campaign to tackle the destruction of the planet was “reckless”. “I’m devastated by the lack of foresight, intelligence, commitment, understanding and determination to do anything about the single biggest issue in our species’ history,” he said. “At a time when we need bold and brave leadership, we’re not seeing any sign from any of the manifestos that that might materialise.” Packham said it would be “a bold ask” to expect the march – attended by celebrities including Judi Dench and Emma Thompson – to put the biodiversity crisis on the political agenda given that it has had “next to no mention at all” in the election campaign so far. But he said he hoped the day of songs, speeches and slogans for wildlife would show there was a growing coalition determined to force the next government to properly fund nature recovery, with further protests a possibility. “What the march should do is send a very clear signal to all candidates that an enormous breadth of society is exhibiting a real concern for nature restoration,” he said. “Don’t think we’re going to go away because we will be banging on the door of No 10 on 5 July saying now is the time for action.” Packham said it was heartening that even a pest management company had contacted him to join the march, alongside organisations from Action for Elephants UK to Unitarians for Climate Justice. Those supporting the march range from global charities such as WWF to grassroots outfits such as Tenterden Wildlife. It will start on Park Lane at midday and end with a rally in Parliament Square. Debbie Tann, the chief executive of Hampshire and Isle of Wight Wildlife Trust, which is sending a coach-load of banner-waving supporters, said: “It will be a really colourful and beautiful celebration of nature but asking our politicians to do much more and much faster to restore nature because we are running out of time. “We need nature and the environment embedded within all policy decisions – it underpins the economy. This is about critical life-support systems and the longer we leave it, the more difficult and expensive it’s going to be.” Beccy Speight, the chief executive of the RSPB, said: “The government signed up to protect 30% of land and sea by 2030 and we’ve got just 3% of English land protected and well-managed for nature. We’re miles off it. We’re not talking about little tweaks from political parties here, we’re talking about really fundamental change in how we think about how nature underpins so much of what we’re trying to do. That’s the thing we’re not seeing from any [political party].” There is widespread dismay among the campaigners at the lack of action for nature in Labour’s manifesto. Mark Avery, a co-founder of Wild Justice with Packham and Ruth Tingay, and a member of the Labour party, said: “The Labour manifesto is pretty good on energy and climate change but it’s hopeless on nature and wildlife and anything that’s rural – there’s nothing really on farming. It looks like it’s been written by people who don’t know what wildlife is and don’t care about it. That’s got to be partly the fault of the NGOs in not getting those messages across sufficiently robustly.” The march is unusual in having large, risk-averse charities such as the National Trust officially present alongside direct action groups. The Guardian understands that some large environmental charities have privately expressed concern that their logos could be seen alongside more radical groups. In turn, direct action groups have their own misgivings about some of the organisations they are being asked to march alongside, in particular animal rights organisations that oppose the RSPB’s limited culling of foxes and other animals. Nathan McGovern, a spokesperson for Animal Rising, said direct action groups had been asked to be on their best behaviour. “It has been made clear that a lot of the larger, more established NGOs who are part of the march wouldn’t like to be associated with anything that causes significant levels of disruption to the general public or causes arrests,” he said. Despite that, most members of direct action groups were positive about the opportunity to march in coalition with established NGOs, even if some regarded it as a somewhat belated joining of forces. Simon Russell, of the Hunt Saboteurs Association, said: “In the wider realms we are obviously all on the same line. We can see the damage done to wildlife and the environment, and we want to see that improving. There’s more links and stuff we agree on than stuff we don’t.” James Skeet, a spokesperson for Just Stop Oil, said: “It’s a promising sign. It certainly wouldn’t have happened a few years back and the hope is that this is the radical flank effect in action. We are viewing it as a mobilising opportunity. “We obviously have a mix of a bit of frustration at times with where the NGO space is at – the response is a bit lacklustre given where we are at, in terms of how critical things are in 2024.” Caroline Lucas, the outgoing Green MP, recently criticised NGOs for “playing it safe”, keeping “a distance from rebels and rule-breakers” and failing to challenge the ideology of the sanctity of economic growth. Lucas said environmental campaigners needed to spend more time talking to people who were yet to be persuaded about the urgency of tackling the triple crisis of climate, nature and inequality rather than “talking to each other on Twitter”. Avery said he agreed with Lucas and added: “Some of the long-established NGOs have become less challenging in recent years and they are the people who keep telling us there’s a nature crisis.” According to Avery, nature charities are often held back by trustees who should be asking “not is it making as much money as it can from selling scones or bird food but is it changing the world enough?”