StunMonsterPower on byrd - weird behavior after it's fallen

[jhp109]

Hi, I'm using StunMonsterAction to apply StunMonsterPower on enemies.
I noticed that if StunMonsterPower (1 amount) is applied on a byrd (a bird monster that attacks with 1x5 or 1x6 damage) and the byrd is fallen down in the same turn, then it will try to attack with 1x5 damage even it is on the ground. Please see the attached screenshot below.

Screenshot - see the leftmost byrd

Thanks,