TV presenter Chris Packham has said he received a "very calculated" death threat against him and his family after he campaigned for measures to protect birds from being shot.
It comes after Natural England revoked licences for controlling 16 species of bird.
Packham said the threat outlined "a list of things they might do" including organising a car crash or poisoning.
He also condemned Facebook for not removing posts containing his address.
The British Association for Shooting and Conservation said it does "not condone any illegal behaviour. And for people to continue to behave in such a manner is utterly unacceptable".
'Bombarded by bullies'
The presenter told the BBC's Victoria Derbyshire programme he received the threat last night, and had reported it to Hampshire Police.
"In the structure of its composition it's designed to elicit as much fear as possible," he said.
"They're principally just saying, 'You will never be safe, you will never be able to go out, we will always be there.'"
Packham's campaign group Wild Justice has challenged the general licences that allow farmers to shoot birds including carrion crows, wood pigeons, and magpies that damage crops or attack livestock.
Individuals can still apply to Natural England - the government's adviser for the natural environment in England - for individual licences to shoot the birds.
The move provoked criticism from farmers' groups and others.
The National Farmers' Union has said it has "significant concerns" about the sudden withdrawal of general licences.
"They are absolutely necessary at this time of year when crops are particularly vulnerable to pests. For example, a flock of pigeons could decimate a farmer's field of crops," its deputy president Guy Smith has said.
"It is incredibly disappointing that farmers and growers find themselves in this position, particularly at this time of year."
Packham has also faced criticism from those who say failing to control the crow population could endanger some of Britain's rarest birds, because the crows raid their nests and steal eggs and chicks.
Last week, two dead crows were hung on Packham's garden gate, and the presenter said charities and organisations he works with have also been "bombarded by bullies".
But he told Victoria Derbyshire that the movement against him had been driven by "fake news".
The aim of his campaign, he said, had been to stop those "who go out with the sole purpose of killing [birds] for pleasure".
He said it would not "make it any more difficult for farmers to be able to control animals that they might consider a pest", but that they would now have to show "they have explored every other means of control" - such as scaring the birds or using netting - before being permitted to shoot them.
He said threats would not stop him from continuing his conservation work.
"People like myself are very dogged and determined," he said.
"I cannot allow these things to sway me. There are too few people standing up and fighting to protect our environment, our landscape, our wildlife."
'Incitement to violence'
Packham also criticised Facebook, on which his home address is posted alongside "invitations to send me dead animals and all sorts of other things".
He said this amounted to "incitement to violence", and he had tried to have it removed.
But, he added, Facebook "are extremely resistant to these sorts of things".
Facebook said in a statement: "There is absolutely no place on Facebook for threatening behaviour which includes disclosing someone's personal information.
"We have investigated and removed several posts for breaking our community standards and sharing Mr Packham's address."