Why do mice eat their own offspring? - briefly
Mice commit infanticide mainly under conditions of limited food, high stress, or oversized litters, thereby enhancing the survival prospects of the remaining offspring. Hormonal shifts after parturition can also provoke this behavior.
Why do mice eat their own offspring? - in detail
Mice occasionally consume their newborns, a phenomenon documented across laboratory strains and wild populations. This behavior, termed filial cannibalism, occurs when the mother or a dominant male eliminates one or more pups from a litter.
The primary drivers are adaptive responses to environmental and physiological constraints:
- Nutrient shortage – limited food supplies reduce the mother’s ability to nourish a large litter; ingesting offspring provides immediate calories and frees resources for the remaining young.
- Excessive litter size – when the number of pups exceeds the capacity of the nest or the mother’s milk production, cannibalism reduces competition and improves survival odds for the survivors.
- Maternal stress – high levels of cortisol or other stress hormones, triggered by crowding, temperature extremes, or predator presence, increase the likelihood of pup removal.
- Health of the pups – embryos or neonates displaying signs of malformation, infection, or weak vigor are often eliminated, preventing the spread of disease and conserving energy for healthier offspring.
- Genetic quality – if the mother detects genetic incompatibility or low viability, she may discard the affected pups to avoid investing in low‑fitness genes.
- Hormonal regulation – fluctuations in prolactin and oxytocin influence maternal attachment; reduced prolactin can diminish caring behavior and promote cannibalism.
- Social hierarchy – dominant males may kill unrelated pups to increase their own reproductive success, subsequently consuming the carcasses for nutritional gain.
These factors interact dynamically; for example, a stressed mother facing food scarcity may both reduce litter size and selectively remove weak pups, thereby maximizing the probability that the remaining offspring reach adulthood. Experimental studies demonstrate that providing abundant nutrition or lowering ambient stressors markedly decreases the incidence of filial cannibalism, confirming its role as a conditional, rather than fixed, behavior.