THE low survival rate of barn owls in the Waveney Valley could be partly due to the loss of set-aside land, conservationists have warned.Suffolk Wildlife Trust (SWT) is claiming that rough grassland that the owls rely on for their food sources is on the decline across the county.

THE low survival rate of barn owls in the Waveney Valley could be partly due to the loss of set-aside land, conservationists have warned.

Suffolk Wildlife Trust (SWT) is claiming that rough grassland that the owls rely on for their food sources is on the decline across the county.

Rough grassland provides vole-rich foraging ground but the decrease in that type of habitat over recent years has meant that females are too emaciated to breed and hatchlings are failing to thrive due to a lack of food.

Despite having addressed the problem of a lack of nest sites by erecting and monitoring nearly 1000 barn owl boxes, mainly in the Waveney Valley, experts at the Trust claim that a lack of voles is preventing the population from rising further.

The Trust's barn owl monitoring studies show that although box occupancy is good, overall survival is low. It believes that the decrease in rough grassland and therefore voles is thought to be due to the ploughing up of set-aside land since 2008 when the requirement for 8pc of farmland to be in set-aside was removed.

European subsides for set-aside - farmland taken out of production - were scrapped in 2007.

Steve Piotrowski, of the Suffolk community barn owl project, said: “Generally vole populations oscillate with peaks and troughs occurring every three or four years. 2007 was an excellent year, but vole numbers fell at the end of 2008 and by spring 2009 female barn owls were struggling to gain sufficient weight to be in good enough condition to breed.”

He said 236 of the 930 - 25pc - of nest sites monitored showed barn owl activity, but only about 90 of them produced chicks.

“Many young owls that did fledge were eventually abandoned by their parents and were left to starve to death and a number were found emaciated,” he said. “Barn owl monitors are hoping that the vole population will pick up next spring and there will be sufficient prey items for the owls to raise families. The loss of grassland habitats, however, is causing deep concern and we are all pinning our hopes on a good up-take of the agri-environment schemes being promoted through the new CFE, by local farmers.”

SWT now has representation on the National Farmers Union's new Campaign for the Farmed Environment and says it will be pressing for an increase in a variety of habitats including rough grassland which should benefit barn owls.