Kern County may require a major developer in its growing wind energy sector to track the radio signatures of California condors and shut down wind turbines if they threaten the endangered birds. As the species rebounds from near-extinction, county environmental reports state, condors are expanding their foraging territory outside of their nesting areas in the Tehachapi Mountains. It is possible that the birds may fly over the fields of 500-foot-tall wind power towers, coming dangerously close to blades spinning at . . .