WASHINGTON (AP) – Government researchers warned 10 years ago that changes were needed in helicopter designs to prevent birds from crashing through windshields and disabling pilots. Today, dangerous bird strikes are on the rise, but there are still no safety standards to protect 90 percent of the nation’s helicopters.

According to the Federal Aviation Administration, there were 204 reported helicopter bird strikes in 2013. That’s a 68 percent increase from 2009, when there were 121 reports, and an increase of more than 700 percent since the early 2000s.

The increase is due partly to greater awareness among pilots about the importance of reporting bird strikes. Another reason is that populations of large bird species are generally on the rise in North America, creating the potential for more dangerous strikes.