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TIP OF THE MONTH September 2010

Mouse control
Rosemary Low

September is the month when every effort should be made to ensure that mice and rats are eliminated from birdrooms and aviaries. During the winter they will seek out the food and shelter they offer. Extremely resourceful creatures, if there is a way to get into our aviaries and birdrooms, they will find it.

If you have outdoor aviaries and you feed your birds in the flight part, mice and perhaps even rats will be attracted. To protect food and water from vermin, weather and the droppings of wild birds (increasing the likelihood of disease being transmitted), it is essential to have an indoor section, either an enclosed shelter or a cage inside a building, where the birds are fed.

If you feed the wild birds, clear up any uneaten food before nightfall and if you keep rabbits or other pets that have a dry food, remove it. Do not discourage your neighbour’s cat from visiting your garden at nightfall. Generally speaking, once a cat has discovered it cannot reach the birds in your aviaries, it will lose interest in them - but if there are mice in the vicinity it will return night after night.

Eliminating mice
The trap is the most environmentally friendly form of elimination. But does it work? At the risk of displeasing mouse trap manufacturers, I have to say that I have never caught a single mouse in the metal traps that catch mice alive. I am told that wooden ones are more successful. The modern ones made of clear plastic are more successful but in my experience they mainly catch young mice, as many mice learn how to exit the way they came in! Obviously traps can be used only in birdrooms where there are no birds loose. They can be used in aviaries only if no small birds are present which could enter the box.

The traditional type of spring trap, usually baited with cheese, can be used if you do not mind removing the victims. Note that mice love chocolate and this can be the best bait of all. Be warned that some very cheap wooden spring traps are almost impossible to set.

 The newspapers often feature advertisements for ultrasonic mouse deterrents. I tried them after being assured they my money would be refunded if they were not effective. My money was eventually refunded! Other breeders’ experiences on this method would be interesting.

 I greatly dislike the use of poison since it can get into the food chain and because death is not swift. Presumably it could also poison a cat if a cat caught a mouse which had eaten poison. Poison should be a last resort. However, to deal with rats and, in some situations, with mice, there seems to be no alternative. The mouse poison which you can buy in a hardware store is unlikely to be effective over the long term, since mice will eventually become immune to it. It is therefore advisable to contact the vermin control department of the local council. Do not leave nest-boxes in position in outdoor aviaries all year unless you close the entrance by nailing wood over it. If a rat enters the aviary and finds a bird roosting inside, it will kill it and you are likely to find a headless victim.

If you place mouse poison in your birdroom, don’t think all you have to do is to put it in a suitable place and wait for the mouse population to crash. Now your work begins. On the first and succeeding nights of poison use in a birdroom, sweep the floor, clean the cage trays, etc, and remove every food container. If they can feed on seed, mice will not take the poison.   They are so resourceful that they can learn to feed during the day but using certain traps or offering them only poison at night will usually solve the problem.

Waging war on rodents must commence before the foundations of the building are laid, at the planning stage. If you decide to build a wooden birdroom or perhaps convert a double garage which is partly constructed from wood, it will be almost impossible to exclude vermin which can easily gnaw through wood. If you must use timber, take the following precautions:

1. Stand the building on a concrete base.

2. Be aware that insulating the birdroom can create a big problem. It does help to prevent heat loss but it is better to spend a little more on heating the room (if heat is necessary) than living with mice breeding in the cavities between the two walls.  Glasswool insulating material might be deemed perfect for mouse nest-making.

3. If you have a wooden building, nail tin plate or aluminium around the outside, to the height of 12in (31cm). This precaution will be useless if there are any holes through which mice can enter. Check the point where electricity cables leave the building, cover ventilator and extractor outlets with small mesh and ensure that all doors and windows are tight-fitting. Also remember that if you have exit-holes to allow your birds access to outdoor flights, mice will enter if they have access to the flights. Welded mesh should be buried around the perimeter of the flights to prevent entry through the floor but unless you use ½ in square welded mesh it will be impossible to eradicate them entirely.

For preference, do not build a birdroom from wood. Brick is much more expensive but if you can afford it, brick or breeze blocks are ideal materials. You might also consider obtaining, second-hand, the kind of prefabricated cabins which are used on building sites, for example, if there is no wood in their construction.

When planning your aviaries, you should consider buying enough welded mesh to double wire all surfaces that are accessible to cats and owls. It might seem like an expensive exercise but this will prevent deaths from injuries by night marauders.