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Wildlife, Mice and Rats!

Friday, 18 September 2009

Wildlife, Mice and Rats!

Last week it was spiders invading our homes, this week it's mice and rats! Our wildlife expert Colin Stafford Johnson will be telling us all about these little creatures and why they may be bedding down in our homes over the next few months.

Colin Stafford Johnson, Loves All Creatures Great And Small

Over the past two decades, Stafford-Johnson has tracked and filmed animals all over the world, including jaguars in the Amazon, tigers in India and birds of paradise in New Guinea. In 2006, he won an Emmy for cinematography on the film Mississippi - Tales of the Last River Rat for Discovery Channel. He has also worked with renowned broadcaster and naturalist David Attenborough on the well-received BBC series Planet Earth. He is currently filming the second installment of his RTE show, Living The Wildlife.

Mice and Rats fall into the category of rodents, are there many different kinds around the world?

About 40% world's mammals are rodents. 2,230 species in the world.

There are seven here. They are;

. House mice
. Wood mice
. Brown rats
. Black rats
. Bank voles
. Red squirrels
. Grey squirrels.

They all have one thing in common. They have very sharp incisors that continually grow. They have to gnaw constantly to keep them sharp. Special teeth. The front of their teeth is very hard enamel, the back is dentine. As they gnaw, the back erodes quicker than the front and that keeps them razor sharp. They are omnivorous. Wide and varied diet. Secret to their success as a group. Grey squirrels can nest in our attics, wood mice may come in occasionally but the problem ones are the house mouse and the brown rat.

Is it known where they originated from?
House mouse and brown rat came from Asia. Followed man. That is the ultimate secret to their success. They have adapted to the way we live. They are omnivores and can eat just about anything although naturally they were probably grain feeders. Short breeding cycles and small size contributes to their success.

How long do they live for?
Both live about two years. One mouse lived to be almost 5 in captivity but that was a massive exception.

In terms of their family set up, there will tend to be one dominant male who defends a harem of several females and their young.

They're known as being prolific breeders, how prolific are they?
They are ready to breed when they are two months old. 3 week gestation. They can have multiple litters a year, normally 6 to 8 per litter, if there is plenty of food around. Move in for warmth and if there is enough food around will continue to breed all year. Their capacity to reproduce though is somehow exaggerated. If you just went by the figures we would be knee deep in them. It's like saying humans are fertile from 14 to 45 and can breed every ten months so in theory a woman could have 30 children. They in turn could breed at 14 etc.
Not the way it works!

Where do they live in our homes?
Both rats and mice avoid light. Neither of them like open spaces. You'll usually find them under floors and in attics. They see them as being good places to nest. They are nocturnal creatures and shun the light and open spaces. They communicate in ultrasonic squeaks above our hearing. If you have a bat detector can pick up those sounds.

An interesting fact is that mice can actually fit through a hole the size of a ballpoint pen!

Are there any benefits to having mice or rats in your home?
No there is not. But as laboratory animals they have done humankind a great service. The rights and wrongs of that are a debate for another day perhaps.

What are the telltale signs that you may have mice or rats living in your home?

Signs that you may have rats or mice living in your home

. Scratching noises in walls or under the floor as they scurry around
. Droppings - mice and rats leave dark droppings.
. Distinctive smell - they leave an ammonia-like smell that will be particularly strong in enclosed areas such as under cupboards
. Damage - they have teeth that grow continuously and gnaw on wood and plastic to keep them trim..
. Ripped food packaging - they will tear open food which may leave teeth marks
. Nests - mice and rats build nests in warm, hidden places using shredded material such as newspaper and fabrics. Nests will often contain their young.
. Burrows - In gardens, rats will dig burrows especially in compost heaps or under sheds. They will also build nests under garden decking.


What advice would you give someone who has mice and rats in their home?
I can't help but admire them for their ability to take advantage of us but it is important to get rid of them. They will cause damage and are not the cleanest. I would live trap them humanely. Keep all food out of their way in the meantime. They will only come into your kitchen food cupboards if they can get to the food.

Will they always be with us?

By the end of this programme today, there will be another 14,000 people on this earth. By the time we meet next week, there will be another 1.4 million of us. Looks like there will be plenty of habitat for them. The future looks secure for rats and mice.

For More Information
The trip trap is available from
Rats and mice are from "The Pet Shop," 96 Patrick St, Dun Laoghaire Co. Dublin, (01)2808940