Voles May Calm Down in a Crowd and Stress Out in Large Spaces

It turns out that voles may be more calm in a crowd than alone. While people tend to feel more anxious in crowds, prairie voles thrive on interaction.

Prairie voles are small rodents that are ubiquitous in meadows and grasslands in the Midwest and Canada. They're one of the few mammals that mate for life, and have long attracted the attention of scientists trying to understand the genetics and physiology of social bonds.

In this latest study, the researchers looked at voles living in fenced enclosures in a hayfield in Illinois. The enclosures allowed the researchers to divide or connect the enclosures to corral the animals into larger or smaller spaces.

The researchers also used radio collars to track the voles and took fecal samples to measure the level of the stress hormone, corticosterone.

The scientists found that voles in the smaller, higher-density enclosures bumped into each other nearly twice as often as those in the roomier, low-density enclosures. However, the voles in the tighter enclosures were also less stressed; in fact, when the vole densities tripled, their stress hormone levels dropped by about 20 percent.

The findings were surprising since crowding usually causes animals to have more stress rather than less. However, it could be that at smaller densities, it may be harder to find a mate. A thinner crowd could also be a sign that predators are near, which could raise stress levels.

The findings are published in the journal General and Comparative Endocrinology.

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