Many people enjoy seeing busy little squirrels running around a park. It might surprise you，then，to learn that some squirrels are in danger. Without protection，you may not see the UK's red squirrels in just ten years.
The main reason is that people brought gray squirrels to the UK in the 1890s. They are larger and longer. They are also better at competing for food and space than red squirrels. As a result，the country's red squirrels are hard to survive.
Another problem is that gray squirrels have brought with them the squirrel pox virus （松鼠痘病毒）. They can carry this virus without any influences （影响） on themselves，but it kills red squirrels. Animals scientists are worried that these problems are having a serious influence.
People in the UK love their red squirrels，so they are doing their best to save them. They came up with a few ideas. One is to stop the gray squirrels from having more babies. With fewer gray squirrels to compete with or spread the virus，the red squirrels will have a better chance. Besides，the trees in the UK will also be healthier，since gray squirrels sometimes hurt trees.
Another idea is to use gray squirrels' natural enemies （敌人） to cut down their numbers. For example，pine martens mainly catch gray squirrels instead of red squirrels. Scientists are putting pine martens in the areas with too many gray squirrels so that different animals can live together better in this way. With these plans，people in the UK hope their red squirrels will make a comeback.
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