Found Kittens? What you should and shouldn't do.
RULE NUMBER 1: If you've found a litter of kittens, it's best to observe them for several hours to see if a Mom cat is coming back. Small kittens have the best chance of survival with their mother and often die if they are removed from their mother's care.
If the Mom cat comes back and is friendly, bring her and the kittens into your home and put them in an enclosed area (separated from any pets). Give the Mom food, water, a litterbox and bedding.
If the Mom comes back and is not friendly or is Feral, leave the kittens with their Mom. Put out food and water daily for the Mom cat to encourage her to return to this safe location. The kittens can be separated from the Mom when they are about 6 weeks old.
For more information, please read this article.