A leading rodent specialist has urged producers to prepare now, as the recent wet weather has extended the breeding season and lead to larger rodent populations.

This summer’s rainfall has affected rat populations in one of two ways, said Jonathan Wade, technical director of rodent specialist PelGar International. “Where fields have flooded, rats have migrated to higher ground or into farmyards early to look for food. In most other areas, where rain has fallen steadily and temperatures have stayed relatively warm, conditions have been ideal for breeding.”

He added: “As soon as the hedgerows are bare and the fields empty of grain, rats will go in search of an alternative food source. And as temperatures fall they need to ingest more calories to survive and find a warm place to live. Although they usually live in burrows, the safety and warmth of deep litter in a poultry shed can also provide good harbourage.

“My advice is to make the area as un-friendly to rats as possible now, before they contaminate feed with their urine and faeces and cause structural damage to buildings.”

The first step is to reduce the places where rats might like to live. Remove and destroy rubbish, broken machinery and piles of old feed bags and clear up any spilt food around feed hoppers and silos.

Repair leaking pipes and drinking systems – rats have to drink every day to survive. Deny them water and they will have to find it elsewhere. Seal the bottom of wooden doors with a metal strip so they cannot gnaw their way through to feed stores.

“Good ‘housekeeping’ will reduce the number of rats that set up home in the buildings, and make it much easier to deal with the ones that do,” said Dr Wade.

“A baiting programme can then be focused on the areas where fresh rat activity is seen,” he said.

Rentokil has reported a 36% increase in callouts for rodent problems. These results compare the period August 2006-July 2007 with August 2007-July 2008.