JUST one pair of adult hen harriers remains in the entire Lothian and Borders region, research has revealed.
It has been estimated the area's expanses of moorland should be able to home 50 pairs of the birds of prey.
However, this year just two nest sites have been occupied and of two pairs alive at the start of the year, just one now remains, accordin
g to a draft report by the Raptor Study Group.
Illegal persecution has widely been blamed for the drop in numbers.
There are currently about 800 pairs of hen harriers across the UK, the majority being found on the west coast of Scotland, where managed grouse moors are uncommon.
Robin Harper, Green MSP, has lodged a motion with the Scottish Parliament calling for the government to urgently investigate why the breeding population of hen harriers has collapsed in Lothian and Borders.
He is also asking for sufficient wildlife crime detection and enforcement resources to be provided throughout the country.
He told The Scotsman: "These depressing figures show the war on wildlife is continuing across Scotland, even when species are meant to be protected.
"It is clear that our defences are not just under pressure, they're down altogether."
He accused the SNP government of putting the self-interest of grouse shooters ahead of birds of prey, and of failing to act effectively on illegal poisoning and shooting.
Mr Harper said: "Last year I called for a review of the resources available to tackle wildlife crime in the full knowledge that they were insufficient.
"(Ministers must] make absolutely certain that our wildlife crime officers are given the support and encouragement that will allow them to do their jobs properly."
Keith Morton, investigations officer with RSPB Scotland, said hen harrier persecution is rife on grouse moors in the Lothian and Borders area.
He said: "Hen harriers are to all intents and purposes pretty much absent as a breeding species from eastern grouse moors. I don't think it's any secret that hen harriers get routinely removed illegally on grouse moors. Grouse moor owners are continually lobbying to be allowed to do it.
"It's been pretty much the situation for decades. The hen harriers were at one point excluded entirely from the Scottish mainland by illegal persecution."
One member of a group that studies raptors in the region, who did not want to be named, said hen harriers were constantly vanishing: "A pair of birds turn up and pair up and display and then disappear. It's happened again and again.
"The trouble is you can't actually prove it (that they are being persecuted]. It's very, very hard to catch them doing it."
Michael Russell, the environment minister, hit out at the perpetrators of wildlife crime. He said: "The Scottish Government believes that crimes against wildlife in general and birds of prey in particular are absolutely unacceptable and demand that all perpetrators are brought to justice for their disgraceful actions."
And he strongly rejected Mr Harper's accusations, saying: "Given that this is one of the issues on which I have been most vocal since taking office, to say that Scottish ministers have remained silent is completely untrue.
"It also devalues the collaborative and co-operative approach which is the only possible strategy to change behaviours.
"Alas, Robin Harper displays an untypical arrogance in running down the efforts of so many people who are determined to eliminate wildlife crime. Robin should stop squawking from the sidelines and join the fight."
