Yellow bar above monsters in Witcher 3

What is the yellow bar below the health bar of ghouls in Witcher 3? So there is the white bar, that sometimes becomes red. That seems to be the health bar. And below it the mysterious yellow bar.

I noticed it on the ghouls guiding the Quen Place of power. Unfortunately, I cannot go back and make a picture, because I bombed the nest. But you can observe it here: YouTube video.

Solution 1:

It's their stamina.

If the enemy expends all the stamina they'll be susceptible to finishing moves and for humans for example, you can drop their shields.

If the tips are enable you can see the tip for drop the shields from humans, but I don't remenber other tips related about the stamina bar.