Yep...
rest the duck, keep her away from others to reduce the stress and urge to get up and roam, feed her well with fresh greens, good feed with some oyester shell mixed in for calcium to aid in healing a broken/damaged bone. Add vitemins to water of feed and supply additional warmth if its cold or chilly.
Ducks make amazing recoverys from orthopaedic type injuries. I've seen a duck that was totally lame, unable to place a foot on the ground, sleep on it and be walking around near normally the next day. Many times they just need rest and quiet. They stress very easily and that delays healing.
I 2nd the turtle warnings. I've seen a small pond turtle make a pass at a duckling. Neighbors said that they witnessed a 3-4" turtle grab a duckling in the pond as the duckling was swimming and take it under never to be seen again......much like a 'gator takes its prey. But, if you have no turtles them thats not the problem. There is no tellin how it happened...plenty of other possible ways for a duck to become injured.
I hope that she heals quickly and returns to her flock soon,
Good luck
I've witnessed a turtle take a duck as well. Luckily I heard the commotion, and jumped in the pond in a true "crazy girl rescuing her duck" fashion.
