It is 10 years since Chris Packham first presented Springwatch and he can’t stop expressing how happy he is that the BBC programme is about to begin again. “I think it’s to do with the atmosphere. There’s this tremendous amount of enthusiasm, energy and joy. I know the narratives will be dramatic and exciting but also purposeful – we’re there to report on the natural world, and we do so with complete integrity.”

His extremely upbeat, ebullient mood is surprising, given recent events in his life. His successful campaign to prevent the ad hoc killing of wild birds recently resulted in death threats against him and his family. As a result of these, he was forced to cancel his appearance at the Dogstival festival in the New Forest this weekend. Two weeks earlier, supporters of bird shooting hung dead crows from the gate of his home and he was sent human excrement in the post.

But Packham, who has Asperger syndrome, is the first to admit he does not think like other people. And when those he describes as “his opponents” do not think like him, he seems to find it easy to focus his mind on whatever he perceives to be more important.

“I’m very pragmatic about what goes on. I don’t let it get to me at all. It never irritates me,” he says. “I see much of the activity of my opposition being counterproductive because it soaks up their time. It wastes their time. They very often shoot themselves in the foot or hang themselves and basically that just allows me to make more progress more quickly. It goes over my head.”

Speaking to the Observer the day before receiving a CBE medal for his services to nature conservation from the Prince of Wales, he says he doesn’t find it difficult to be both environmental campaigner and impartial BBC presenter. “The programme’s mission is not to campaign and I accept that. I like what the BBC stands for. I like its impartiality.” For him, what matters most is the mission Springwatch does have: “To get people to engage with British wildlife. And I love it. Because then, outside of the programme, I can ask them to look after it. I can pick up where the programme leaves off.”

He is unperturbed that the BBC is bombarded with calls to sack him. “Of course my opponents constantly complain. These are lobbying bodies: that’s their job. If they weren’t complaining, I would say they were abusing their funders’ pockets.”

When he speaks out against wildlife crime, for example, he knows his words will be twisted to appear controversial. “That’s a tool of their trade. They also generate fake news – misquoting, misattributing, misconnecting things I say to create mischief. But that’s the modern world. There’s nothing I can do about it. There’s no point moaning about it because it could get me down. I just have to understand it and work against it, perhaps even harder than I would otherwise.”

Facebook Twitter Pinterest Chris Packham and Kate Humble presenting Autumnwatch in 2009. Photograph: BBC

He has agreed with the BBC not to talk about some of his campaigning work during the periods when Springwatch is being broadcast live. “I don’t want to compromise a broadcaster I respect and love, so I work very hard not to trip up. I’m very careful.” As a result, “if people make complaints, it’s relatively easy for the BBC to rebuff them And that’s what happens.”.

He thinks, like the schoolgirl environmental activist Greta Thunberg, that his autism is part of what makes him so determined to fight for wildlife conservation. “One of the traits [of people with Asperger’s] is that we are incredibly intolerant of injustice. I’ve never tolerated it, my whole life, even petty things at home or at school.” If something is wrong, he wants to right it. “That didactic nature is quite a driving force when it comes to the campaigning that Greta and I might do. We see the lack of activity by our politicians with regard to climate change as being wrong. Not quite wrong, but wholly wrong. That sense of injustice pains us and we strive to overcome it.”

Another trait is candour. “We are very truthful. It isn’t difficult for us to say exactly what we think, and we can do that without compromise. People might perceive what I say as controversial. It’s not, from my perspective. Very often, I’ve voiced something that to me is common sense. I’m bemused they might perceive it’s controversial at all.”

He doesn’t care if saying what he thinks makes him unpopular. “My public profile is built on telling the truth, saying what I feel and arguing ferociously for it. I never sit down and think: is it a good idea to say this, at this point in time? Maybe I’ll just say half of it? That filter is not there.”

But he does struggle with some aspects of the fame that presenting Springwatch has brought him. “I just work all the time. I never stop working. Because as more opportunities have arisen for me to make a small amount of difference, I have to seize them. I cannot pass them by.”

His activism takes it toll on his partner, Charlotte, and adult stepdaughter, Megan, he admits, and even he finds his relentlessness “exhausting” sometimes. “I’m extremely fortunate that they understand. But I’m not saying it doesn’t exasperate them. Perhaps I need to make more of an effort to find a compromise, to be a bit more normal. But the people who are closest to me are inevitably going to suffer the most, because it’s with them that I need to let my guard down.”

Facebook Twitter Pinterest Packham with a barn owl, 1989. Photograph: Rex

At work, he continually reminds himself he may unintentionally cause offence, due to his Asperger’s. “I’m constantly doing two jobs. I’m doing my actual job, and I’m also managing myself so that I can do my job. I’m constantly thinking: how am I working in this team? What do I have to do – and not have to do?”

He explains: “For instance, don’t keep interrupting them, make sure you’re looking at them, try and empathise with them when they feel strongly about something you don’t give a damn about. All of those things I have to keep pinching myself under the table to be conscious of. When I go home, I want space to be me. And that’s why my family have the toughest time – and why I live in the woods in the middle of nowhere.”

But it’s all worth it, to him, for the joy of spending almost four weeks during Springwatch just focusing on British wildlife. “I get to do what I did when I was a kid, but using technology I never dreamed would be available.” He finds it particularly thrilling when he can tell the audience something new that has been discovered about a well-known species such as a blue tit, or turn a romantically challenged stickleback into a national star.

He never feels nervous about presenting live, he says, because if he makes a mistake he can simply correct it later – and he takes pains to do so. His near-photographic memory also helps: “I have the ability to recall things I read months ago in explicit detail.”

Equally, he can’t forget how much wildlife has declined in Britain over his lifetime, and carries with him an almost visceral sense of loss. “I walk in a quieter field now. I stroll through a more silent wood. I remember with clarity, because of my memory, how different it was when I was a kid – the volume of song. That reinforces my sense of urgency to make a difference before my time runs out. I’ve realised I’ve got less time to clear up a bigger mess.”