how to care for an orphan duckling?

My youngest son just phoned me...... he's picked up a mallard duckling from the side of the road.......

Some other driver had run over the rest of duckling's family....... =(

Don't know yet if duckling is injured, or how bad. Son tells me that he's got a scuff on the top of his head, and he's not to anxious to walk. (probably scared silly)

I've suggested son keep duckling in an old wire rabbit hutch in the deep shade, (it's supposed to be blisteringly hot today) provide water, grass and a bit of bird seed (canary type seeds),

Duckling is probably shocked, to say the least.......

So we will see how he's doing when I get home from work tonight....here's hoping he's well. I guess that will determine any next steps..

Are we on the right path for this little duck? Any other advice?