Cindy, don't feed anything you are not sure of.
You need to learn to identify your trees with confidence. I'll see if I can find an online guide to help you. Some of them will walk your through leaf type, arrangement of leaves on the stem, etc. etc. and lead you to the answer.
If you have a knowledgeable friend, get him or her to walk around your property with you and name the trees. Then double-check online and see if they are safe for rabbits.
Apple, pear, willow, elm, sugar maple, silver maple, sycamore, and poplar are all safe. See the safe plants list to get the botanical names if you are not sure what tree species I mean.
I have no experience of citrus trees, living this far north, but perhaps someone in the southern states can help you.
Edited to add:
This website might be helpful to you.
http://74.125.93.132/search?q=cache:OaD ... clnk&gl=ca
I found several references to cottontail rabbits damaging young citrus trees, which would tend to indicate that the twigs are not toxic. If you feed them to your rabbits, try it with one rabbit several time before putting them all at risk.<br /><br />__________ Wed Jan 06, 2010 10:44 am __________<br /><br />
http://forestry.about.com/od/treeidenti ... _start.htm