Quote:
Belated, but FWIW, I'm gonna quote Storey's Guide, chapter 14, page 205* under 'Growing Duck Feed':
"Our favorite perennial plants for producing significant quantities of food and shade in our duck yards include mulberries, Siberian pea shrub (Caragena arborescens), and grapes...The fruit and seeds from these plants require no harvesting because they fall to the ground when mature and the ducks eagerly consume them."
*I believe I have the second-to-most-recent edition, so page number may vary.
If they're one of Holderread's favorites, seems to me it's probably safe!