Tree rats (fruit rats, black rats, palm rats, attic rats, roof rats, etc) are rattus rattus, an arboreal rat, nocturnal in nature. Few people know they have them until they experience some fruit damage. Many attribute the damage to other critters, but the damage is classic. See
http://edis.ifas.ufl.edu/uw120. In April we had over 100 people at our place for a CRFG tour. I showed them a trap, rat damage, and how to control them. Folks duplicated the trap arrangement, hung them in their trees, and caught many tree rats. E-mails went around with photos, measurements, and rat competition. These rats rarely go on the ground, living in trees. The traps I use (20 of them) are normal rat traps screwed to an 8 ft 1X2. Trigger baited with a macadamia nut (drilled for attachment) facing down. A deck screw is attached to the opposite side of the trap at the top of the pole enabling it to be hooked up in a tree. That's it. But....birds will get killed too, so I encircle the trap with 1/2 in hardware cloth, open at both ends. Rats get in, caught. Birds stay out. Sometimes predators will eat most of the rat-on-a-stick, but usually are simply dropped into a hole for future fertilizer. The link shows the considerable problems caused by these rats. A neighbor has them in his attic and NO pest control operator has been able to get them. He is afraid of poison resulting in the stench of death. So he hears them running around every night. They are there, even if you don't see them. The reproductive rate is fast. Good luck with this worthy adversary.