Lots of helos use separator devices, variously called EAPS (engine air particle separator) or IPS (inertial particle separator) to remove sand, dust etc. from inlet air. It's a bit of a drag on engine performance, but pays off by reducing compressor erosion for longer service life.
Depending on the dimensions of the device, it may be effective on birds, but could be a real hazard in ice.
The H-53's deployed on the Iranian hostage rescue mission (1979) used EAPS, which was probably a mistake because they reduced engine output (and thus helo lift capacity); When you're on a life-or-death mission, you really don't care if the engine lasts an extra 2000 hrs.
