They are calling for an action group to be set up to investigate the deaths.
Despite the offer of a reward approaching £30,000 for information leading to the prosecution of those behind the killing of the 14 red kites and six buzzards, they have not been found.
Police and conservationists are at a loss to explain why the evidence of the worst modern episode of persecution of raptors has been found on farmland, when the crime has normally been associated with driven grouse moors in the past.
Ewan Macdonald farms near Conon Bridge. Several of the birds were found near his land, and his properties, including his sheds, barns and house, including his bedroom, have been searched by police.
Prominent in farming circles, he said in an interview with the BBC that the reputation of the local farmers, who had positively supported the reintroduction of red kites in the Black Isle area, was being tarnished.
"All of the farmers are saying they are very concerned about this because we are worried that our industry again gets its name blackened," he said.
"Hopefully, and I am almost 100% certain, it has nothing to do with the farming industry and I would find it very shocking and very surprising if it was. As an industry we are desperate to get to the bottom of this and that is why I want us to get together and see if we can pool our resources.
"We have nothing to hide, but I would like to get round a table with all of the organisations and see if we can put some sort of plan together to get to the bottom of this."
Mr Macdonald said that Black Isle red kites were common overhead at this time of year. He added, however, that they would not harm the lambs. He suggested an action group made up of landowners, the police and the RSPB to help solve the mystery.
He said that if police would release information on the sort of pesticide or chemical that had been found in the birds confirmed to have been poisoned, it would allow them to help more in the search.
Explaining that red kites were a common site over his land, he described how "they hover over the lambing field because they like picking up the remains of the afterbirth of lambs. They do no harm at all to the lambing field.
"Our men love seeing them and we are very fond of them. It is only in the last 20 years that the population has built up quite dramatically. We are absolutely devastated by what has happened over the past two or three weeks."
Contributions from the public to the reward have risen to well over £5000, on top of the £5000 offered by RSPB Scotland and matched by an anonymous donor. The local members of Scottish Land & Estates and the NFU Scotland have put up £12,000.