Treetec provides a range of canopy access services including nest box installation and monitoring, tree access training, research, canopy engineering solutions, cavity installations and consulting.
Nest boxes can provide a quick and relatively affordable solution where nesting sites are needed, they have successfully been used to reintroduce and/or sustain endangered fauna communities. There are however a range of variables and nest boxes can be unsuccessful unless the project is well designed. Where nest boxes are not the best solution Introduced cavities may provide a viable alternative.
Key failures with nest boxes usually relate to the method of installation and location of the boxes. There are plenty of good resources on selecting boxes suited to fauna species, and manufacturers that can supply them at reasonable rates. Most wooden boxes will last between 5 and 12 years depending on location and construction methods.
- Box design – ensure your box is well suited to your target species, particularly the diameter of the opening as this is often the key factor that can exclude larger competitors. Additionally consider internal dimensions, height to opening (or depth of cavity), wall thickness / insulation, ventilation, drainage, construction materials and fixing method.
Fixing – how a box is attached to a tree will determine how much movement there is and how much damage is done to the tree; a loop of wire around a branch or trunk allows boxes to move excessively in the wind and this seems to impact fauna acceptance. (more on fixing methods below). Allowance may be needed for tree growth to avoid damaging the box.
- Aspect / sun – natural hollows are generally well insulated, nest boxes are much more susceptible to extreme temperatures, particularly over-heating. Ensure nest-boxes are shaded from summer sun, particularly afternoon summer sun. Place the box in dense shade and/or on the Southeast side of the tree (Southern hemisphere)
- Materials – can the target species climb the inside of the box, get a grip or land near the opening, is the paint toxic, will the wood rot quickly, composite VS wood, will sharp edges or hinges cause a problem. Does it need a latch to stop larger animals or predators opening the lid, could it be constructed to more closely resemble a natural cavity with natural materials?
In general there are two fixing methods for nest boxes; hanging with rope or wire or drilled / screwed into the tree. Often a hanging system is chosen to avoid wounding the tree however we usually recommend against this. Use of wire or chain to hang a box will inevitably create a large horizontal wound where the wire cuts into the tree, insulating the wire with hose lasts only a few years, leaving the wire loose or sprung allows the box too much movement. Hanging from rope is usually short lived as the rope degrades.
Drilling the tree does create two wounds however usually provides a much more secure fit for the nestbox. Those wounds are not significant and unless the tree is a very old, significant tree we would suggest the wounds are sustainable. Large old trees are less able to compartmentalise decay and therefore any wounding including drilling should be avoided.
When drilling a nestbox to a tree with coach bolts or similar the box should be secured top and bottom and there should be a collapsible spacer which allows the tree to grow without crushing the box. There are alternatives that work such as allowing the nestbox to slide outward on large pins as the tree expands.
Competitors and predators
As mentioned above smaller animals are easily displaced by larger or more assertive competitors if the nest-box design is not well considered. Additionally the design and placement of a nest-box should consider predators. There is a recent case of native arboreal marsupials being snatched by cats who sit themselves on top of the box and wait for the rare and tasty treat to venture out.
Consider what type of vegetation is preferred, height, aspect and connectivity. The nesting preferences of a larger bird of prey will be very different to a small marsupial.
Many nest box programs limit the height of the box to facilitate access for research and maintenance, however this also brings the nest closer to ground based predators.
Canopy access and climbing for nest boxes
Generally the less you disturb native fauna the better. If a box does need monitoring then consider a pole mounted camera. Additionally box occupancy can be checked from the ground using a thermal camera, although this does not tell you the species in residence.
Use of a ladder is the simplest way to reach a low nest box however ladder use often results in falls, there are now some simple and secure rope and harness systems that can be used to secure the climber of a ladder eliminating much of the risk. Treetec runs canopy access and ladder use courses for Melbourne or Victorian groups who need to safely install, check or repair nest boxes.