Read the following paragraph and summarize its content around 30 but no more than 50 words:
In recent years, the desire to find a clean, renewable source of energy has led to an increase in the number of wind turbines in the United States. Wind turbines are tall pillars topped with spinning blades, which create energy when they are turned by strong winds. Unfortunately, these turbines are having an unintended consequence: collisions with wind turbines injure or kill many bats during the bats' annual migrations. The result has been a noticeable decrease in the populations of many species of bats. Researchers have proposed three solutions to save the bats from being harmed by wind turbines. One solution is to build wind turbines at sites where they would not interfere with the bats' migratory patterns. A second solution is to shut down the current wind turbines at night time when bats are most active (bats are night animals.) Finally, a third solution involves the use of radar to keep bats away from the wind turbines.
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