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

"We're getting more severe damage, more frequent cases of birds penetrating the windshield and the risk of pilot incapacitation that could cause fatalities for everybody there," Gary Roach, an FAA helicopter safety engineer, told a recent meeting of FAA's aviation rule making advisory committee.

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

In March, for example, a Dallas police helicopter was searching for a capsized boat when there was a loud explosion and wind began rushing through a huge hole in the windshield. The pilot, Sgt. Todd Limerick, put a hand over one eye, which was embedded with shards of Plexiglas. His nose was broken and blood covered his face. But he kept his other hand on the controls until the copilot, Cpl. Laurent Lespagnol, took over.

"My first thought was that we had been shot. My second was the engine blew up," Lespagnol said. It wasn't until they had landed that they found the cause wedged between the cockpit seats - a 3-pound American coot, a ducklike bird.

The increase is due partly to greater awareness among pilots about the importance of reporting bird strikes since January 2009, when US Airways Flight 1549 was ditched in the Hudson River after the airliner's two engines sucked in geese.

But another reason is that populations of large bird species are generally on the rise in North America, creating the potential for more dangerous strikes.

For example, the Canada goose population in North America increased from about 500,000 in 1980 to 3.8 million in 2013, according to the U.S. Fish and Wildlife Service. During the same period, the snow goose population increased from about 2.1 million to 6.6 million.

Despite the increase in big birds and bird strike reports, the number of incidents in which airliners suffered serious damage from a bird strike has been dropping, in part because of efforts to keep airports and their surroundings free of large birds. The reverse is true of helicopters, which fly at lower altitudes around lots of birds.

Roach cited the example of a helicopter pilot in the Gulf Coast region who was flying around 1,000 feet and 115 m.p.h. when two ducks slammed through the windshield and hit him in the face. The pilot had so much bird gore on his face, he couldn't immediately breathe or see. Some of his teeth were knocked out, his jaw wouldn't close for a month, and he needed stitches. But he still managed to land the helicopter without injuring any of the other five people on board.

The report on the incident read: "Bird strike. Landing uneventful," Roach said. "But that really didn't represent what was going on in the cockpit."

Current FAA regulations, developed in the 1960s and 1970s, require airliner windshields and airframe surfaces to withstand the impact of a 4-pound bird, and the tail to withstand an 8-pound bird. For helicopters weighing more than 7,000 pounds, windshields must withstand a 2.2 pound bird. But no bird-strike safety standards exist for helicopters weighing less than 7,000 pounds, or about 90 percent of the U.S. fleet.