A JOINT police investigation is underway after two tagged, bred in captivity hen harriers went missing.

The juvenile birds of prey were two of an original five bred in pens as part of a trial brood management scheme and released onto moors in the north of the country.

Data from the tags show that one of the male hen harriers has travelled close to 1,800 miles, averaging around 55 miles per day, travelling as far west as the coast of southern Ireland, and to Southampton, London and Wales.

The others have all remained closer to home in the north of the country, with data showing at least two of the birds travelling to Ingleton, Bentham, Horton-in-Ribblesdale and into the Forest of Bowland.

Superintendent Nick Lyall, of Bedfordshire Police, chairman of the national Raptor Persecution Priority Delivery Group (PDG) has tweeted the two missing birds were the subject of live investigations by police in North Yorkshire and in Durham, and added: “There will be no further police comment at this time while investigations continue.”

The birds were reared in pens before being relocated to moorland where they were released, and although data is still being received from three of the birds, the tags on the two remaining hen harriers have stopped transmitting.

The tags are solar powered, which can result in stretches of time where no data is transmitted, and have malfunctioned in the past with tagged birds being spotted from the ground or the transmitter suddenly retransmitting.

Amanda Anderson, director of the Moorland Association, which is a partner in the brood management scheme trial, said: “This data provides a fascinating insight into the behaviour of these captive-reared young harriers. They appear to have integrated very well and their behaviour seems the same as totally wild tagged harriers. Most of the birds have been content to fly around the uplands and grouse moors which is territory they know and like. The adventures of the bird which travelled further afield are extraordinary and show that the species is quite capable of covering vast distances.”

She added members of the Moorland Association were enthusiastic participants in the scheme and that extensive efforts were being made to trace the two that had stopped transmitting.“The areas to search are massive over difficult moorland terrain hunting for a well camouflaged bird the size of a big crow. Whilst it is expected that at least 50 per cent of birds will succumb to natural causes of death in the first six months we very much hope to find the birds alive or at least find them to establish cause of death,” she said.

This year is said to have been an encouraging year for hen harriers with a total of 15 nests, 12 of which were successful in fledging young.