Shalom H!
To keep a population in an equilibrium (= the same more or less population density )only 2 from ALL OFFSPRING of a single feamale have to reach adulthood, so the situation you have described is quite common.......
Shalom back at you, Benny! Are you and your family doing well?
AND those 2 offspring must then be able to produce 2 adult offspring... Still, doesn't make me happy! The crows do chase off the hawks, which is a good thing. Yes... equilibrium is sometimes brutal to watch.