SCIENCE
07/30/2015 09:22 am ET

How To Tell If Your Hamster Is Happy

Simply "enriching" a hamster's cage can induce positive thinking in your pet, scientists say.

Is your pet hamster high on life -- or just a sad little ball of fur?

A new study from England suggests that -- just like humans -- some hamsters can have a shift in mood, from a gloomy demeanor to a more rosy view of life, for instance. What's more, the research shows that it doesn't take a whole lot to boost a hamster's mood: some hammocks to lounge in, a bit of extra bedding, and a chew toy or two can make a big difference.

"Hamsters are often a child’s first pet and we’ve shown that what goes into a cage (ledges, chews, hammocks and material to dig in) has a positive impact on a hamster’s emotional state and thus, their well-being," Dr. Nicola Koyama, senior lecturer in ethology at Liverpool John Moores University and a co-author of the study, said in a written statement.

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A hamster in the study playing in its "enriched" environment.
Alexandra Robinson
A hamster in the study playing in its "enriched" environment.

For the study, the researchers trained 30 male Syrian hamsters to associate sugar water with a drinker placed on one side of an enclosure and to associate bitter-tasting water with a drinker placed at the opposite side. The hamsters quickly learned which drinker in the testing area held which liquid and returned again and again to the sugar water drinker while avoiding the bitter water drinker.

Then half of the hamsters got additional enrichment devices in their cages -- such as extra bedding, hammocks, and ledges -- allowing the hamsters to live in luxury for about a week. Meanwhile, the researchers reduced the number of enrichment devices in the other hamsters' cages. 

Hamsters in the study enjoying their hammocks.
Nicola Koyama
Hamsters in the study enjoying their hammocks.

After the animals became habituated to their new homes, they once again were presented with the sugar water drinker, the bitter water drinker, and this time a third drinker was placed in between.

What happened? The hamsters that had been given more enrichment devices were more likely than the other hamsters to approach the ambiguous drinker. The scientists concluded that the extra enrichment made the hamsters optimistic that the new drinker might contain sugar water.

"This study shows that hamsters housed in enriched environments make more optimistic judgements about otherwise ambiguous information," Dr. Emily Bethell, senior lecturer in primate behavior at the university and the study's lead author, said in the written statement. "The important note for pet owners is that ensuring pets have adequate opportunities to express natural behaviors in captivity improves their mood and is essential for their welfare."

Smithsonian magazine reported that the hamsters' optimistic behavior was strikingly similar to that seen in humans, who may experience similar emotional circumstances -- as entertained and engaged people also may be more upbeat and optimistic.

What's next for the hamsters in the study? They have been adopted by students at the university who are studying animal behavior, USA Today reported.

"They have happy endings here," Bethell told the newspaper, in "very loving homes."

The study was published online in the journal Royal Society Open Science on July 29, 2015.

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