How do solitary animals like cats live in groups?

Most feline species display solitary and territorial behaviors. However, domestic cats often live together with several other conspecifics, raising the question of which strategies they use to establish cohabitating groups. A research team led by the Azabu University in Japan has now explored the relationships between domestic cats’ social behaviors, hormone levels, and gut microbiomes, shedding more light on how these solitary animals can frequently live in high densities.

The scientists conducted a two-week-long study of three different groups of five cats living together in an animal shelter. They used video cameras to observe and record the cats’ behaviors, measured hormone levels in their urine, and evaluated the mix of microbial species in their gut microbiomes from fecal samples.

The results revealed that cats with high levels of the hormones cortisol and testosterone had less contact with their conspecifics, and those with high testosterone levels were more likely to try to escape from the shelter. By contrast, cats with low levels of testosterone and cortisol were more tolerant towards other cats. In addition, the researchers found greater similarity of gut microbiomes between cats who had more frequent contact with each other.

Surprisingly, contrary to the scientists’ expectations from previous research on animals that live in groups, cats with higher levels of the hormone oxytocin were not more social and willing to bond with others. This finding suggests that oxytocin might have different functions for typically solitary animals living in groups than for animals that typically live in groups.

“Low testosterone and cortisol concentrations in cats enabled them to share the space and live together, but the higher the oxytocin, the less affiliative behavior with others and the lonelier they are. The function of oxytocin was different from that of affinity for a group-mate. Cats may not consider other individuals living in the same space as tight relationship group-mates,” explained the study authors.

Further research is needed to better understand the dynamics of cohabitating cats, such as a longer follow-up study to observe cats for several months, rather than only two weeks, in order to properly clarify the causal relationships between hormones, microbiota, and social behaviors.

The study is published in the journal PLoS ONE.

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By Andrei Ionescu, Earth.com Staff Writer