As humans, we often think about social stress in terms of the anxiety we feel in anticipation of a social encounter. For rats, social stress occurs as a response to a negative social confrontation. It is experienced by both sexes but tends to occur more often in males.
In the wild, male rats live within two different systems depending on the population density of rats in the area. At low population density, they are territorial – defending and holding territory and a group of females. This involves fighting off challenging males.
In areas of high population density, male rats are hierarchical. With the highest-ranking rats having primary mating rights to any female who is on heat. Maintaining position involves fighting off challenging males.
Pet rats live in the conditions of high population density and live within a hierarchical system. They have been bred for docility and (often) with no mating opportunities at all, hierarchies are typically easy to establish and can be maintained for life.
Most pet males tolerate incoming young males well, and introductions involve a bit of posturing and pinning of the newcomers before the hierarchy is established. However, sadly, this is not always so.
Rat relationships are complex, and hierarchies rely on more than one individual to maintain the structure. The outcome for the whole group depends on the temperament and confidence of everyone within it.
Rats can have issues accepting unrelated rats into the ‘in-group’. This is an unnatural thing to do and runs against instinctive behaviour. Age is another factor – with testosterone fluctuations in late adolescence (10-12 weeks) and physical maturity (8-10 months) often being flashpoints for introducing newcomers.
To learn more about this important subject check out this Social Stress PDF in the Ratwise Store.
What is social stress?
Social stress refers to any stress that an animal experiences as part of having social relationships. It is usually experienced between members of the same species, but it is likely that domesticated animals can also be triggered by their relationships with humans.
The most severe social stress that a rat will experience is losing in a social encounter with another rat. There is a great deal of research that informs us of how threatening this scenario is to our rats.
Because this research is studying stress it often makes difficult reading, but it’s important for us to learn from it. Doing so, can bring some rat-centric purpose to these studies, and can help us to improve the way we manage the care of the rats we are responsible for.
By measuring physiological responses in rats, researchers have found that being the losing rat in a conflict situation is more stressful than stressors like immobilisation, forced swimming, or electric shocks. Pause for a moment and let that sink in.
The stress a rat feels in losing in a social power struggle is so intense because the loss of position and place in the hierarchy is a threat to survival and reproduction – which are the driving forces behind all life.
It is essential as rat guardians that we understand the importance of social stress, recognise it in our own rats, and can mitigate against it. The research indicates that for some rats only one incident of intense social defeat is needed to induce a PTSD response.
In a world where we sometimes repeat ‘failed’ introductions several times over a period of months, the impact of social stress can be intense. Understanding this can help us interpret our observations and know when to change our approach.