Communal Nesting in Rats

Would you believe that rats do have a complex to share litters in a single nest? The females are often the ones involved in this kind of behavior, wherein some mother rats share their care with other youngling of another mother's rats. They call such occurrences as communal nesting. Both mother rats will then share the responsibility of raising their young together. The question now is why do rats have this sort of complex and how do they deal with such situations wherein they get to share the responsibility of raising their young with other mother rats. We do not wish to cover the entire literature and understanding of this rat behavior but we hope to pinpoint the relevant matters to the readers of this article.

In General

In simple terms, communal nesting is simply the sharing of two mothers of their younglings, in terms of care and rearing. In such instances, mothers may also share their milk with the younglings not their own.

But, not all mother rats are likely to cohabit in a communal nest. There are only certain members of the species that undergo such process. Usually, there are particular preconditions and factors that have to be fulfilled and herein, familiarity and affinity plays a vital role in the possibility of the commensalism. If a pair of sister rats have lived together for the entire time of their existence until they have produced litters, they are most likely to share their younglings in the future in a communal nest. However, if two female rats have only known each other for only a couple of weeks, communal nesting is most unlikely to take place due to the aloofness of the two female species. Often even, such forced interactions would most likely result to aggression to both females and even infanticide. This happens because when stranger females decide to pool their litters together, one female may eventually rise as the dominant female and would most likely monopolize the entire litter.

Infanticide is perhaps one of the most common problems between rat mothers, especially those that are unfamiliar with each other but live in a communal nest. Infanticide occurs because litters are often unsynchronized, therefore younglings arrive in different time frames. 44% percent of unfamiliar mother females, cohabiting in a communal nest, the second mother which is still pregnant, will most likely kill all or some of the litters of the first mother. On the other hand, only 11% of sister rat mothers undergo through infanticide.

Sister pairs of rats have another complex of inequality. The second batches of litters borne from the sister pairs are most likely to suffer more mortality than the first batch of litters. This happens simply because young ones are forced to compete with the older ones in terms of care from their mothers, especially in terms of milk nursing. Another conflict would also arise when first born litters would suck milk from their aunt's mammary glands which could often damage the gland making it incapable already of nursing its own litters when the time come they will be conceived.