When contemplating how to attach your bird feeders, birdhouses and/or wind chimes do not attach them with nails, screws or anything that will penetrate the outer bark. Texas A&M Forest Service has a great explanation on why one shouldn’t:
Penetrating the outer bark can damage the cambium, the area just beneath the bark where cells rapidly divide and increase tree girth. It also can wound the phloem, the cells that carry nutrients from the canopy to the roots; and the xylem, the cells that transport water and nutrients to the canopy.
Puncture wounds offer easy access to insects and diseases. Vascular plants lack immune systems; when a tree is wounded, a chemical reaction takes place and the tree establishes boundaries around the wound that stop or limit the spread of disease and/or decay. This compartmentalization, however, breaks down if the tree is wounded again, as a newly damaged area retriggers the process.
Depending on the tree’s size, health and species and the spacing of the punctures, Merritt says, 10 holes could cause enough structural and health problems to kill the tree.
Some species are better at compartmentalization than others, he adds. A live oak, for example, is good at it; a water oak generally is not. Another potential problem: A tree will eventually grow around nails or screws, making them hidden dangers for arborists who prune with chainsaws.
If you must attach an object to a tree, use a strap at least a half-inch wide and check annually to make sure it’s not strangulating the tree.