Conservationists have launched a new study to learn more about the migratory movements of a rare bird of prey throughout the Wensum valley.

Marsh harriers, once driven to extinction in the UK, have made a comeback in East Anglia in recent years – particularly in Norfolk, where nesting sites include the Sculthorpe Moor Community Nature Reserve near Fakenham.

The reserve is owned by the Hawk and Owl Trust, which is carrying out the research to fill gaps in naturalists' knowledge about where the birds go after they fledge their nests.

Fourteen harriers have been fitted with distinctive lime green wing tags, each with a two-figure identifying code comprising letters and numbers printed in white.

The painless tagging was carried out by experienced bird ringers led by trust volunteer Phil Littler with help from Gary Elton of the Norfolk Ornithologists Association, Ray Gribble and Allan Hale from the Wensum Valley Birdwatching Society and John Middleton of the North West Norfolk Ringing Group.

Eight of the tagged youngsters fledged from nests at Sculthorpe Moor, and another six came from nests in nearby locations.

Nigel Middleton, conservation officer for the Hawk and Owl Trust, said: 'Twenty years ago this study would not have been undertaken, as no-one would have dreamed of approaching a marsh harrier nest because they were such a rare breeding bird.

'Although they are still very rare birds the numbers of marsh harriers now breeding in Norfolk means we are in a better position to study this bird and have been given permission by Natural England.'

Mr Middleton said the study aimed to discover whether marsh harriers were long-distant migrants to Europe or beyond for the winter, and if they returned to the same reed-bed where they hatched to breed once mature.

For several years cameras installed on nests at the Sculthorpe Moor Nature Reserve have given an insight into the lives of young harriers. Data from the resulting film is being analysed by students at Leicester University but little is known about the birds' movements once they leave the nest.

Marsh harriers are migratory and are expected to fly south, however in recent years many have been spotted along the north Norfolk coast and the Broads in winter.

The marsh harrier became extinct during the 19th century. The birds bred sporadically in the Broads between 1927 and 1975, but since then their numbers have risen steadily. Today, more than 100 females nest in Norfolk each year.

The tagging project has been funded by the Pensthorpe Conservation Trust with money raised at its Wild about the Wensum events.

?The public can help the study by reporting any sightings of wing-tagged marsh harriers. The letters and numbers on the tag should be noted, along with a date, time and location (if possible, as a six-figure Ordinance Survey grid reference). The sex and age of the bird should also be recorded if known.

?Contact Phil Littler at phillittler10@yahoo.co.uk or phone 07748556758.