A female Norway rat can have five litters a year with an average of seven baby rats each time — that’s 35 new rats each year.
Say half of those are girls, and all of them had 35 baby rats that year, that’s 612 new rats, and if half of them had babies, that’s something like 11,000 rats in a year, and given that they can get pregnant when they turn five weeks old, that’s actually a pretty conservative number.
This is the nightmare scenario that keeps Adam Schroeder up at night. He’s the director of the Ada County Weed, Pest & Mosquito Abatement, and he’s been sounding the alarm about the growing rat infestation that’s spreading its way around the Treasure Valley.