I was expecting it to be something like they eat a percentage of their own babies or something.

Well… If you insist.

https://en.wikipedia.org/wiki/Tasmanian_devil

“Gestation lasts 21 days, and devils give birth to 20–30 young standing up … As there are only four nipples in the pouch, competition is fierce, and few newborns survive.”

One guess as to what happens to the spares.