There's Life in Hazard Trees

The goals of hazard tree management programs are to maximize public safety and maintain a healthy sustainable tree resource. Although hazard tree management frequently targets removal of trees or parts of trees that attract wildlife, it can take into account a diversity of tree values. With just a little extra planning, hazard tree management can be highly beneficial to wildlife while maintaining the goals of the program. The objective of this information guide is to provide considerations regarding wildlife when making decisions during hazard tree assessments. The decision-making model provided with this guide can be used as a tool during tree inspections.
What is the link between hazard tree management and wildlife?
There are more than 120 species of birds, 140 kinds of mammals and 270 species of reptiles and amphibians that nest and forage in dead or deteriorating trees. Often in hazard tree management, it is the dead and deteriorating parts of a tree, or the entire tree (such as a snag), that is removed. This can negatively impact wildlife populations and species that are dependent on these trees as essential habitat components. It is likely that these trees may not be replaced for years. As the number of cavity trees decrease, wildlife species that depend on cavities may disappear.
A tree that has:
... a potential to fail
+ a potential to strike a target*

=hazard tree
Why are considerations for wildlife important?
Surveys demonstrate that wildlife is important to people. In a recent study, landowners identified wildlife as a key reason for owning land. Other studies show that, in urban areas, 93% of residents want to know how to attract wildlife and support habitat, and each year 49 million people in the U.S. enjoy feeding and watching birds. In addition, some threatened and endangered species use snags, cavity trees, or dead and down logs as important habitat components. When a tree dies, its usefulness does not end, its role simply changes.
* A target is:
anything of value that a tree or part of a tree could strike when failure occurs. (i.e. a person, structure, vehicle etc.)
How to identify trees currently and potentially useful to wildlife.
A few ways to identify trees currently used by wildlife include: Trees potentially useful to wildlife include:
1. observations of wildlife using a tree .... 1. trees with decay
2. signs of wildlife use (existing cavities, dens or current woodpecker activity in a tree) 2. trees with fungal conks (a sign of decay)
3. presence of fresh scat or bird droppings in, on or around a tree 3. trees with broken off tops and branches
4. trees with old wounds or scars
If a tree does not have a cavity , it can still be used by wildlife. Dead or partially dead trees without cavities can provide foraging, perching and nesting sites for non-cavity nesting species.
Where and when is it appropriate to consider wildlife in hazard tree management?
It is appropriate where and when human safety is not compromised.
Who benefits by using hazard trees and for what purpose?
forage sites
nest sites
chickadees, great blue herons, ospreys, wood ducks, mergansers, woodpeckers
den sites
raccoon, fisher, pine marten, porcupine, gray and flying squirrels, cottontail rabbits, snowshoe hare, bear, bobcat
singing perches
roost sites
bats, tree frogs
Wildlife Habitat / Hazard Tree Decisions Model

NA logo Prepared by: Mary Torsello, Pathologist and Toni McLellan, Wildlife Biologist, USDA Forest Service, Northeastern Area, State & Private Forestry, Durham, NH Forest Service Shield
horizontal ruler
PDF PDF - There's Life in Hazard Trees