Scientists have debated the purpose of the ultrasonic vocalizations (USVs) produced by rodents since the discovery of these sounds in the 1950s. There's a wide research consensus suggesting USVs are a form of social communication, a courtship display, which though inaudible to humans, might otherwise be compared to the calls of certain birds.

Of course killing the Younglings after Mouse Order 66 was carried out wasn’t a big deal since the rodent mothers do that all the time anyway.