Did you find a wild rabbit baby nest in you backyard?

Do you think they are abandoned?

Unless you see an actual injury, it is best to leave wild baby bunnies alone and assume that the Momma Bunny will come back later to feed them.  
She usually stays far away from the nest to prevent the nest from being discovered by predators; she only returns once a day for just a few minutes to feed the babies. 

The babies will almost surely die without their Momma's milk so don't bring them inside, move the nest, or take them to a refuge.  Rabbits are good mothers. 
It is far more likely that the Momma will return than that she has abandoned them.  Many people with good intentions due more harm by assuming the babies are orphaned.