Conservationists say a young hen harrier has disappeared from a grouse moor where three golden eagles went missing in the spring.

RSPB Scotland announced that a young male hen harrier, can't be found on a grouse moor in the Monadhliath Mountains, the range which runs to the west of Strathspey and the A9, and to the south-east of Inverness.

The species is under threat. At the last count in 2010 there were 662 breeding hen harrier pairs in the UK; 505 of those were left in Scotland after a 20 per cent decline since 2004.

The bird, named Elwood, was featuring in a part EU-funded RSPB project.

It was the only chick to fledge from a nest in Banffshire, which was being was monitored under the Partnership for Action against Wildlife Crime Scotland (PAW Scotland) “Heads-up for Harriers scheme”.

The transmitter’s data indicated that the young bird left its nest in the first week of July, but stayed close to the site in the hills above the River Spey until the 20th, when he began to travel more widely. By the 27th, he had moved 20 miles to the south west, and had settled in the hills around Tomatin.

The bird remained in this area, with the transmitter providing detailed information about his daily travels until suddenly, transmissions ceased abruptly on August 3. The bird’s last recorded position was on an area of managed grouse moorland a few miles from the Slochd summit on the A9.

It follows the row last week when the RSPB pointed the finger at shooting estates after another satellite-tagged golden eagle had also disappeared in the northern Monadhliaths, making it eight since 2011. Three of these birds, whose transmitters were also functioning normally, went “off the radar” this spring. The raptors predate young grouse, but the landowners' organisation said there was no evidence whatsoever that estate staff had anything to do with the missing birds of prey.

However following Elwood's departure, Ian Thomson, RSPB Scotland’s Head of Investigations, said: “The transmitters being fitted to these birds are exceedingly reliable, and illegal persecution is therefore the most likely explanation of the disappearance of these birds of prey. "

He said there were a good number of enlightened estates happy to host and protect nesting birds of prey. "But as soon as they move away from these areas they are being illegally killed.

“The denials and obfuscation from representatives of the land management sector, and their consistent failure to acknowledge and address this problem, is one of the main reasons why our bird of prey populations are struggling in the central and eastern Highlands. "

The Scottish Government should introduce a robust system of licensing game bird hunting, in line with most other European countries, he said.

But a spokesman for The Scottish Gamekeepers Association said: "As with other recent allegations, the SGA will work with Police Scotland and Scottish Government in an attempt to get to the bottom of this. It is clearly a situation which cannot go on. We have no independent information, at the present time, so getting the facts will be the first step. Speculation, at this stage, will not help.

"The SGA does not, and will never, condone wildlife crime. As an organisation we advocate legal solutions, solely, as the means to resolve conflicts. If there is any evidence of illegal activity by an SGA member, appropriate action will be taken."