 |
|
Cavity Trees and Your Woodlot
S&W Report / Summer / Fall 2000, Vol 20
|
Owning a woodlot has a lot of advantages. You can manage your woodlot for a multitude of objectives that will bring years of satisfaction to you, your family and to future generations. If one of your objectives is to maintain and enhance wildlife habitat for cavity users - read on.
Maintaining cavity trees in your woodlot contributes significantly to the health and well-being of a number of birds and mammals. Cavity trees offer nesting sites, shelter from adverse weather, protection from predators and feeding opportunities that are an integral part of the habitat for a number of wildlife species.
Habitat
In most cases, an undisturbed forest will have enough cavity trees to provide for a good population of cavity users. These woodlots would normally have a sufficient number of standing trees with decay present that given the stand structure of the woodlot, a variety of cavity users could utilize.
However, sometimes our management activities in the woodlot will alter this supply of habitat. For example, during our fuelwood removal we normally target those trees showing signs of decline and decay in favour of those trees that are healthy and defect-free. These "cull" trees are some of the very trees cavity users require as part of their habitat. With this in mind, leaving cavity trees should always be considered whenever you are cutting wood in your woodlot - whether it is for personal use or for a commercial operation.
Table #1 shows a listing of some birds that use cavity trees in northern hardwood forests. These cavity users are divided into two groups - excavators or secondary users.
|
| Table #1 - Cavity-hole Nesters of Eastern Woodlots |
| Species |
Excavator |
Secondary User |
Optimum Diameter of Snag (inches) |
Diameter of Hole (inches) |
Height Above Ground (Feet) |
Habitat |
| Pileated Woodpecker |
x
|
|
20
|
4
|
N/A
|
Older mature forests; larger treesl extensive forests |
| Screech Owl |
|
x
|
12
|
3
|
10-30
|
Open forests; meadow edges; orchards |
| Great Crested Flycatcher |
|
x
|
12
|
2
|
6-20
|
Forest interior; edges to lesser extent |
| Eastern Bluebird |
|
x
|
8
|
1 1/2
|
5-10
|
Forest field edge or savana-like habitats |
| Downy Woodpecker |
x
|
|
12
|
1 1/4
|
6-20
|
Dense young forest |
| Tufted Titmouse |
|
x
|
12
|
1 1/4
|
6-20
|
Deciduous forests; suburbia |
| Black-capped Chickadee |
|
x
|
4
|
1 1/4
|
6-20
|
Almost any kind of forest |
Source: Forest Service - North Central Forest EXperimental Station
- U.S. Department of Agriculture |
|
Back to the top
Improving the Habitat
What can you do in your woodlot to create and sustain suitable habitat for cavity-nesting birds? Here are a number of options you may want to consider:
Maintain a number of larger diameter trees with broken limbs or visible signs of defects (conks) in your woodlot. Bigger is better - these are the most valuable to cavity nesters. Generally, smaller cavity users can use a larger tree, however, the same can be said for a larger cavity user.
|
 |
A Typical Cavity Tree |
|
When you are cutting fuelwood or carrying out harvesting operations in your woodlot, leave a few dead, dying and decayed trees behind (remember safety first - only leave dead trees in isolated areas when it is safe to do so).
To assist in creating natural cavities, you can select a limb at least three inches in diameter and prune it off at about six inches away from the trunk. Over time this stub will form a natural cavity. Trees of poorer form and value should be selected if one of your management objectives is also timber production.
A hole bored into the centre of a living tree will eventually allow decay and will enlarge over time to create a cavity. Holes should be drilled under a limb three inches or larger in diameter.
How many cavity trees should be retained in your woodlot? The Silvicultural Guide to Tolerant Hardwood Forests in Ontario recommends that six cavity trees per ha should be retained. One cavity tree measuring 40 cm or more at breast height should be retained, with the remaining five cavity trees measuring at least 25 cm in diameter.
Back to the top
Table # 2 provides additoinal information on the various birds and mammals that require cavities as part of their habitat.
|
Table #2 - Cavities Used by Birds and Mammals in
Northern Hardwood Forests |
| Species |
Excavator |
Secondary User |
Optimum Diameter
of Snag (inches) |
Tree Type |
Cavity Use |
| Wood Duck |
|
|
>8
|
LBTL
|
Nesting
|
| Barred Owl |
|
x
|
>18
|
LBTL
|
Nesting & Perching
|
| N. Saw-whet Owl |
|
x
|
6 to 18
|
DH, LBTL
|
Nesting, Perching, Roosting
|
| Hairy Woodpecker |
x
|
|
6 to >18
|
DH, LCD, AND LBTL
|
Nesting, foraging, perching, roosting
|
| Yellow-bellied Sapsucker |
x
|
|
8 to >18
|
DH, LCD, AND LBTL
|
Nesting, foraging perching, roosting
|
| Red-breasted Nuthatch |
|
x
|
8 to 18
|
LCD, LBTL
|
Nesting, foraging, roosting
|
| Big Brown Bat |
|
x
|
hollow >24
|
Hollow
|
Roosting
|
| Red Squirrel |
|
x
|
>18 and hollow >24
|
Hollow, LBTL |
Denning |
| Soutnern Flying Squirrels |
|
x
|
6 to >24
|
DH, LCD, LBTL |
Denning |
| Porcupine |
|
x
|
>18 and >24 hollow
|
LBTL. Hollow |
Denning |
| Fisher |
|
x
|
>18 and >24 hollow
|
LBTL. Hollow |
Denning |
|
DH = dead trees LCD =live trees with central decay
LBTL= live trees with broken tops and limbs
Source: Guide to Wildlife Tree Mangement in New England Northern Hardwoods
|
|
Recommended Reading
The following guide is an excellent source of information for woodlot owners wanting to read and learn more on managing for wildlife trees in our hardwood forests.
Tubbs, Carl H., DeGraaf, Richard M., Yamasaki, Mariko, Healy, William M. 1987. Guide to Wildlife Tree Management in New England Northern Hardwoods. General Technical Report NE-118. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 30 pages.
A copy of this guide can be obtained by calling (740) 368-0123 or visit the Northeastern Forest Experiment Station Web Site .
Back to the top
|
|
|
|
|
