Wild speculation department: Some wild bird eggs have identifying patterns visible only in the near-UV, which some birds see quite well. These patterns allow the nest owners to tell their own eggs from imposters left in their nests by cuckoos and the like.
Don't know that robins play that game. But in terms of chemical bond structure, blue pigments would be somewhat adjacent to near-UV pigments, and there might well be some overlap in their visible light spectra.
Maybe there's a connection along those lines. Either that, or the robin equivalent of Martha Stewart likes blue, and that's what they all go with.
all these burns did not happen at once this time. maybe over a month. but most of them look like something was set on fire on the bike path and got away.
Rode out last week to check on our two Piper Creek community garden plots that we rent from the municipality which contracts a local herder to use their goats to manage invasive weed species on the adjacent parcel of land.