

Rats will bury their cache for later dining. He may have burried it and another came along and, dug it up and consumed the rest.
The original rat , or others, smelling the cache spot would dig to try and find the spoils.
Most all wild carnivores will do this, large cats will even stash the remains in trees for later snacking. But most small rodents will dig a hole and bury. Just like a dog with a bone.
A few of the left over feathers around the trap will lure other rats to investigate.
Be careful of bringing wild birds from outside in...weather dead or alive. They could have disease or mites that could contaminate your aviary
