Given the gestation period for the species is between 102–138 days, and the article states the young rat was born in July, I rather suspect the female arrived at Chester whilst already pregnant.
However, as this species is able to breed twice during the annual reproductive period, it is very possible another birth - and hence a true first breeding at the collection - will follow soon.
However, as this species is able to breed twice during the annual reproductive period, it is very possible another birth - and hence a true first breeding at the collection - will follow soon.