A reliable source of information about domestic rabbits, wild rabbits and parakeets

In order to decide what needs to be done with the baby rabbit(s) you just found, you must first determine it's age and health condition. 

If you find a nest
If the nest has been disturbed, and the babies are scattered about, the first thing to do is see if any of the babies are injured.  If they are not, then rebuild the nest and put the babies back. Nests can have three to eight babies, so if they are scattered try to find them all.  Mom should come back unless she has been hurt or killed. If one or more babies are hurt, remove them from the nest and call a rehabilitator.  But DO NOT leave only one baby in the nest - it needs the others to keep warm.  Since Mom comes at dawn and dusk, you can put a criss-cross of dental floss across the nest and check to see if it's disturbed the nest morning.  If it was, then she has come back - keep your dogs away and cats indoors.  They will grow up and be gone in three weeks.

If Mom has not returned:
Check to see if the babies have round bellies or flat bellies.  If their bellies are round, then they are not starving and you can give mom another day.  Sometimes the mother will stay away for a feeding or two if she sees that the nest has been disturbed - she wants to stay safe. If their bellies are flat or sunken in, then they need intervention.

Pics to come.

KEEP THE BABIES WARM.  If you hold them in your palm, they should feel warmer than your hands.  If they are not, give them an external source of heat.  When in shock, the body cannot keep warm on its own.  External sources of heat can be a heating pad on low, under the box they are in (line the box with a towel, do not use the nesting material, as it may have bugs or dirt that can get in wounds).  If no heating pad is available, fill a water bottle with hot water, wrap in a towel or put in a sock, and place next to the babies.  Or you can use a microwaveable pad, or microwave a sock filled with rice.  Be careful not to burn the babies with the source of heat.