I think it was from "New York State Conservationist" magazine, but I'm not sure- it was years ago, but the article was entitled "The Mathematical Mouse".
A pet mouse was living in a cage with her six offspring and her mate. One day, somehow, one of her young got out of her nest. She searched frantically for the sixth offspring, and when she couldn't find him... she picked up her mate and hauled him to the nest.
The mice's owners carefully poked around the litter in the cage and found the missing baby mouse. They replaced the father with the baby, the mother woke up and counted six babies, and she went back to sleep.
Peasant (1963-1972) and Fluffy (1970s?-1982- I think of you as 'Ambrose' now)- Your spirits outshone some humans I have known. Be happy forever.