Small poop

[Thumperina]

I have 3 bunnies who live outdoors, and it's been rather hot recently (around 100F)
They are fed green veggies that they do eat, a bit of fruit, they have unlimited grass in the yard (they don't favor hay). For unknown reason, they don't drink water or drink very little (getting enough fluids with grass?) I noticed that poop doesn't look right recently (small in size). I try to ease their being by offering them cold wet veggies during the day. Heat makes them inactive.
Anyway.. I need to make sure that heat is our only problem and I am not missing anything important and serious.
What can I do for them?

 

[AmberNikSee]

I would continue to add water to their veggies, and you could try adding a little unsweetened pineapple juice to their water. You don't need much as it is high in sugar on its own but it adds flavor and makes some buns drink it like its going out of style.