just a thought!

[cj.morris]

when I first kept gerbils in my youth I remember that my gerbils always
seemed to have 8 pups in their first litter and 6 pups in successive
litters...

is the fertility of gerbils falling or are their other reasons for this, as
nearly all the 'pup announcements' seem to show average litters to be
smaller
these days (and blanche only had two in her first litter)