Zone 4: The Crown
Almost every large tree has dead branches. However, the location and amount of dead wood in a tree can tell you much about its health. Dead branches in the lower sections of a tree are normal and usually a sign of inadequate sunlight. The tree will naturally shed these. Branches dying back from the tips indicate that the tree’s health is somehow compromised, though dead twigs might be too small to cause any threat to a climber. A large number of dead branches high in the treetop usually means the tree is dying. Brown leaves or the absence of leaves (with the rest of the tree in full leaf) indicate a dead branch. The loss of bark and/or fungus growing on a branch also indicate a dying or dead branch.
The 
most obvious way to prevent risk in a tree is to remove dead or broken branches. Dead branches can be easily spotted when the tree is in full leaf. Use binoculars for a closer look as you look for broken branches. Pruning a small amount of annoying twigs that get in your way does not harm a tree.
Decay or rot pockets sometimes exist on the upper side of a branch, making them invisible to ground observation. To avoid accidental branch breakage, it’s better to climb a tree close to the trunk (trunk route) if it is a wild or unfamiliar tree, rather than climbing out on branches (branch route). The weak branches need to be pruned or avoided in future climbs.
"Widow makers" are life-threatening broken branches that are hanging precariously or lodged in a tree. These branches can come crashing down with a slight wind or be shaken down or dislodged by a gentle touch by a climber in the tree. Climbers of wild trees must be constantly aware of dangerous broken branches, which should be identified and avoided.
IMPORTANT! Dead branches and widow makers should be removed by the lead climber before the rest of the climbing party enters the tree. When widow makers or dead branches are being removed, it is particularly important that the lead climber, as well as those who might be even remotely near the tree on the ground, wear a helmet.
