My guys love Kale! It's really the best green in terms of nutrients. I actually discovered kale with my guinea pigs, who went nuts for the stuff!
Mine prefer it all chopped up, but the only downer to this is that it dries up and gets wilty pretty fast. (Though it's a bit better if you put it in a pile....which they spread out in short order, but it staves off wilting until they decide to eat it.)
So I usually chop up with a knife, and also put up a full leaf for the latecomers. (I think I have the same clip as you,
Delray. It's a little yellow clip intended for millet. I wish I could find another! It came with a package of millet ages ago and I've never seen one again.)
Be careful, though, if you have guys who are nesting.
I can't offer the full leaves when they're involved in nest building as otherwise, the leaves end up as part of the nest!.....all wilty and icky.