The death of individual branches could be due to twig borers, tiny beetles that bore into branches and in the process introduce a fungus that kills the end of the branch. To check for twig borers, carefully examine a dead or dying branch at the area where the dead wood begins, looking for a tiny round hole. This hole is only about the diameter of a straight pin, so very careful examination is needed to find it. If this evidence of twig borers is found, prune out the dying branch below this hole dispose of it. Keep the tree healthy with good care practices. Death of the tree is very unlikely. These twig borers occur on several types of trees and are often found on red maples and oaks.