Bugging You From San Juan Island

Posting a few photos of our resident Pileated woodpeckers (Dryocopus pileatus) . This is Dad, “Woody,” and “Junior.”

What do they eat? While they are indeed visiting our suet blocks during their reproductive season and will also come by in the winter when food is scarce, the actual diets of a Pileated Woodpecker (Dryocopus pileatus) or other species of woodpeckers are comprised of many of the wood-boring, tunneling, and wood-eating invertebrates that help forests stay healthy.

How could an insect (or an insect-eating bird) that bores into trees be good for a tree? As the saying goes, “sometimes it is hard to see the forest for the trees.” While this is complicated due to climate change, our narrow views tend to see herbivory or holes in a tree, and even a dying tree as a bad thing.

We have to step back to understand the whole picture – which is – a dynamic process. A healthy ecosystem is not static, but one of renewal and regeneration, always changing. The wood boring bugs that are eating inside a tree are (typically) part of the early breakdown stages of a tree that is already dying. As they tunnel and bore though the dying tree, they help decompose the dying parts, releasing nutrients back into the system for new trees and other organisms to grow.

Compared to a human lifespan, this is not a rapid process, but an ongoing, multi-generational one that sustains many other organisms over a vast period of time. In a nutshell, the birds, like these woodpeckers, take advantage of the dying trees hosting wood boring beetle larvae and other wood-eating or wood-tunneling bugs. As the beetles, and ants, or termites tunnel, chew, or eat through a tree, they attract and feeds other organisms that feed on the insects. The insects and the birds leave behind sawdust and frass which is, in turn, broken down by other organisms – earthworms, millipedes, centipedes, etc. In actuality, the processes at hand are far more complicated, but in a nutshell, healthy ecosystems include death.

When you walk out onto your property and see a dying tree, don’t necessarily see it as a bad thing. Watch for a while. Are the woodpeckers pecking holes? The tree may not fall over for many, many years. As it dies, it will host so many various lives: from spiders in tiny crevices, beautiful moths (often unseen, but important pollinators), iridescent beetles that will emerge from some of those tunnels, woodpeckers, cavity nesting birds, including owls that need a sheltered place to rest and rear young. Just maybe, if you consider these things, you will refrain from taking down and chipping or burning that “dying” or “dead” tree and leave it to stand many years instead. When it does finally fall, perhaps you will consider leaving it to decompose on the forest floor where it will continue to host the lives of many organisms that are necessary and good for a healthy and balanced ecosystem. Nature will thank you. The San Juan Islands are a special place. Let’s not turn our home into a mainland suburbia.

*Fun fact: The diets of Pileated Woodpeckers are known to be comprised of 85% carpenter ants. Re-think your decision to put insecticidal baits out around your property. Those stumps are the equivalent of a grocery store or local co-op for these birds. Leave them to decompose naturally.

References

Bull, E. L. (1987). Ecology of the pileated woodpecker in northeastern Oregon. The Journal of wildlife management, 472-481.

Raley, C.M. and Aubry, K.B. 2006, Foraging Ecology of Pileated Woodpeckers in Coastal Forests of Washington. The Journal of Wildlife Management, 70: 1266-1275. https://doi.org/10.2193/0022-541X(2006)70%5B1266:FEOPWI%5D2.0.CO;2