Around this time I noticed that a vent hole in the side of the shed was uncovered, and likely had been for some time, which I fixed.
A few months later I was doing a good spring cleaning, and I found in the eaves of the shed a nest made mostly of long pine needles (from outside the shed), but with a substantial spattering of through-hole components too!
A bird had found the broken vent, and made a home in the shed using whatever ‘sticks’ were handy to build its nest. Unfortunately I probably blocked it off from its home when I repaired the vent. I’m glad to say no eggs or dead baby chicks were in it when I found it…