I wrote about this in my mara post.
Maras will raise their babies communally.
However, females will allow only their offspring to nurse.
So you do get tense situations when the guard changes at the crèche.
This story reminds me of a documentary on sheep I saw a few years ago.
This Scottish shepherd had a ewe that had given birth to three lambs, but because these were hardy Highland sheep, he didn’t want to nurse a lamb and turn it into a pet.
One of his other ewes had given birth to the usual twins, but one of these twins died shortly after birth. The ewe had nurse the lamb and was bonded to it, but it just died.
Ewes will not nurse lambs that are not their own, so the extra lamb that the other ewe had could not be fostered without some innovation.
The shepherd skinned the dead lamb, and then he dressed the third lamb in its pelt.
The foster ewe thought the third lamb was her baby, and she allowed him to nurse.
The third lamb continued to wear the skin of the deceased for a day or two. By then the third lamb had drank enough of its new mother’s milk to smell right.