SIR – The rat population in this country is on the rise. Knowing which pests are eating vital food provided for birds and finding a solution were essential parts of our new study (“Pheasant shooting feeds a rise in rats”, report June 9).

Our previous research has shown that pheasant shooting can be a force for good in the countryside. Providing food during the lean times of winter for game birds is very beneficial for a suite of other farmland birds, including declining species such as yellowhammer and corn bunting.

However, inadequate pest control is failing to control the explosion of the rat population. Increased maize production could also be contributing to the problem.

Now that we have identified the level of the problem, we are looking at ways to mitigate it, such as improving hopper design.

Dr Carlos Sanchez-Garcia Game & Wildlife Conservation Trust Fordingbridge, Hampshire SIR – We have acres of maize game cover here on the Berkshire Downs, and dozens of wheat feeder stations during the shooting season.

The problems start after the season ends, when the game cover is ploughed in and the feed stations remain unfilled. With their food source gone, the rats come breaking and entering. They climb the walls of houses to get into the loft, commit daylight robbery on bird tables and hold swimming races in garden ponds.

Since rats, unlike roe deer, are worth nothing to gamekeepers, we householders are left to deal with the influx ourselves.

Kevin Fiske

Hungerford, Berkshire