Question

making towers bird - friendly
read the passage.
the lights on tall communication towers warn pilots to avoid the towers when flying at night. unfortunately, the steady red lights often used on towers have the opposite effect on birds: the bright beams attract and confuse them. instead of avoiding the lights, the birds fly directly toward them, crashing into the towers or becoming entangled in power lines. millions of birds have died this way. however, there is a solution. unlike steady lights, flashing or blinking lights dont attract birds. in response to demands from conservation groups, the federal aviation administration in 2016 began requiring communication towers in the u.s. to use blinking lights instead of steady ones.
what is the main, or central, idea of the passage?
birds are attracted to the steady red lights on communication towers.
to save birds, communication towers have begun using blinking lights.

Explanation:

The passage discusses the problem of birds being attracted to steady red lights on communication towers, leading to their deaths. It then presents a solution: using blinking lights instead. The Federal Aviation Administration in 2016 began requiring communication towers in the U.S. to use blinking lights to save birds. This is the main idea as it encompasses the problem (steady lights attracting birds) and the solution (blinking lights to save them).

Answer:

To save birds, communication towers have begun using blinking lights.