I believe that is Nandina, i would not plant one in a pen, it is toxic and birds may not eat them when free ranged but given the fact that some birds will try anything sometimes in a pen.
I have some texas lilac seed that i can send anone that wants them for the cost to cover shipping, they will survive in the poopest soil and grows very fast proving your birds with hours of shade.
THey make tons of seeds and birds love them
look them up on the net and you can see how pretty they are. Bees love them also