I don't recall hearing nighttime insects before I stupidly left Portland in 2011. After I came back in 2014, I noticed crickets (and maybe other critters) making it sound like a warm Southern night around here. Is this global warming at work once again? —Happily Re-Adopted Portlander
Having grown up in Southern Illinois, a stone's throw from Kentucky, I'm well-acquainted with the nighttime insect sounds you describe, and I too recall noticing their absence when I moved to Portland.
I didn't really miss it, however, because I also noticed that in Portland, you could open your front door without slathering yourself with bug spray first. Why, people here left their windows open without screens. If that's a lack of biodiversity, bring on the silent spring.
But this past summer, I also started noticing cricket songs at nightfall for the first time.
Of course, the ranges of many living creatures have been shifting northward as the planet warms. Clearly, the phenomenon you and I are noticing is the result of various noisy arthropods, newly arrived in the area as they slowly migrate toward Canada.
To confirm this hypothesis, I put in a call to Joshua Vlach, entomologist with the Oregon Department of Agriculture, who was able to state with confidence that we're both completely full of shit.
He put it in more polite terms: "Perhaps you're older and more observant than you used to be?" Vlach gently explained that Oregon has at least five native (as in "have been here the whole time") species of cricket, plus native katydids, native tree frogs and probably a few other native creatures that go buzz in the night.
Mind you, insects do migrate. Mild winters recently allowed the mountain pine beetle, deadly to pine trees, to jump the Continental Divide, and it's now poised to decimate eastern North America.
But in our case, it's probably not rising global temperatures, but rising local rents, that are to blame. I don't know about you, but since 2011 I've been turfed from lower Hawthorne out to the pine barrens of St. Johns, where my nearest coffee is Starbucks and my mailman is a bear. Nature is easier to hear when you're closer to it.