Can I critically hit a chicken?

I recently acquired the Hand of the Prophet relic for my Enchantress that enables all her skills. As a result she's now polymorphing enemies into chickens, an ability I had never previously used.

I've noticed that when attacking the enemies as chickens, their health bar goes down but critical hit damage numbers never appear over their heads like they do when I normally attack. Does it just not show this for enemies polymorphed into chickens, or is my Enchantress actually doing me a disservice by making these enemies crit-immune for the duration of their polymorph?