It's been fairly well studied in voles. A quick search turns up a paper titled: > A mechanism for population self-regulation: Social density suppresses GnRH ex

It's been fairly well studied in voles. A quick search turns up a paper titled: > A mechanism for population self-regulation: Social density suppresses GnRH expression and reduces reproductivity in voles I wouldn't expect an absence of food to do it, but instead a surplus of neighbors. By the time overpopulation starts affecting the food source it's a little late to do anything about it.