Stopping a megawatt wind turbine on a dime to save a bird might introduce structural issues.
That isn't the case with solar thermal. Radar or sonar can track each bird as it passes through the farm feeding information into a controller. Each mirror would only be diverted from the boiler for a fraction of a second.
Only the offending mirrors need to be moved to allow a bird to pass that movement only needs to be a minimum angle, just enough to de focus the heat.
This is a really cool engineering problem. They probably would not even need to beef up the motors since it's such a log distance from the mirrors to the boiler.