The short answer
Yes — blackberries are a safe berry treat.
Why
Like other berries, blackberries offer antioxidants and vitamins, and the tiny seeds are harmless. They're sugary, so keep them a treat.
How to feed it
Wash and offer one, whole or mashed. Expect harmless purple staining on the beak and droppings.
How much & how often
One or two, a few times a week.