Field Notes Knotholes
~ by Jim Eagleman
I
set aside some interesting pieces of wood gathered from my walks in the forest and from working at the woodpile with a splitting maul. They all show a knothole where a branch had attached at one time and had either grown over or the wood had rotted to soften it. Ones with what looked like the right size hole for a bird to enter could become a part of a nest birdhouse. I’ ll design some birdhouses from the collection. They needn’ t be fancy— and that’ s good, given my limited carpentry skills.
I once read cavity nesters comprise a near majority of the songbirds that nest here( over 80 species). And cavities can exist more readily in old and dying trees, dead snags of living trees, or in the main trunk. Dead and declining trees may seem an eyesore, but they are an important habitat component of cavity nesting birds. Cavity nesting is a reproductive strategy used by some species to protect their nests from weather and predators.
There are two types of cavity nesting birds: primary and secondary. Primary cavity nesters excavate nest holes, secondary cavity nesters rely on the abandoned cavities. As with many things in nature, recycling occurs.
The best example of a primary cavity nester is the woodpecker. They are excellent at excavating holes in trees using their chisel-like beak to chip away at a hole, sometimes for several days, until the cavity is complete. They are also considered to be a keystone specie by providing shelter and nesting sites for other birds.
There are seven species of woodpeckers in our area and that breed here. The most common are the northern flicker, downy, hairy, redbellied, and pileated woodpecker, all frequently seen. Less likely seen, but still occurring, are the red-headed and the yellow-bellied sapsucker.
54 Our Brown County • Jan./ Feb. 2025