House mice navigate and communicate through urinary scent marks.
This is established rodent behavioural science, not a repellent company's white paper. Mice deposit urine marks continuously as they move, and those marks aren't waste they're signal. Published work shows they carry information about species, sex, individual identity, social dominance, and reproductive and health status, encoded in proteins within the mark itself. Mice read what other mice have left and adjust accordingly.
So the one you heard at 2:47 wasn't only travelling.
It was writing.
Those marks build a map of your building. Where the food is. Which routes are safe. Which cavity stays warm. Where a dominant animal holds territory.
And here's the part that explains your November:
When you remove the mouse, the writing stays on the wall.
It doesn't stop when the trap goes off. It doesn't stop when you pack the gap. It doesn't stop when the van pulls away.
It stays in the surface of your home, legible to every rodent within range, until something actually removes it.
And the bleach didn't remove it.
Orkin's own cleanup guidance says so outright: bleach may disinfect but does not neutralize the compounds that cause the odor. Their recommendation is an enzyme-based cleaner on every hard surface where urine was present, repeat treatment on porous material like wood and concrete, and outright replacement of heavily soiled insulation, drywall or carpet padding.
The chemistry: mouse urine is high in uric acid, which doesn't break down easily. It dries into crystals that bond to the surface and reactivate whenever moisture returns.
The mark isn't sitting on your baseboard. It's in it.
And pest-industry sanitation guidance is blunt about the result unsanitized marks stay usable for navigation, and the scent of a previous infestation draws in new rodents looking for a home.
You didn't fail to catch them all.
You caught them all and left the sign up.