SYDNEY (Reuters) - The theft of a fully-grown emu from an Australian wildlife park this week has left only a pile of feathers at the scene of the crime, and questions about the motive for snatching an ungainly bird with practically no cash value. Operating under cover of darkness, robbers are believed to have lifted the flightless bird - second only to the ostrich in size and known for its speed, powerful legs and clawed feet - over electrified barbed wire atop a two-meter fence, eluding a guard and a security camera. Police evidence suggests a getaway vehicle was parked about 1 km (0. ...