Mink react to boredom in much the same way as humans - by eating too many snacks and idling away their time, scientists have found.
Researchers believe the findings show captive animals can suffer psychologically from a lack of things to do.
The scientists compared mink living in small, bare cages with those housed in large enclosures containing passageways, water pools, climbing towers and chewable toys.
Those in the bare cages actively sought stimulation, even if it meant approaching normally frightening objects. They also ate more treats between meals than mink in the enriched environments.
When not being tested, the mink in the bare cages spent much of their waking time lying down and idle. Those that spent the most time awake but motionless were also the ones showing the keenest interest in boredom-breaking stimulation. The findings are reported in the online journal Public Library of Science ONE.
"We don't know whether mink or other animals truly feel bored in the same way that humans do," said researcher Dr Rebecca Meagher, from the University of Guelph in Ontario, Canada.
"We can't measure that type of subjective experience. But we can see that, when they have little to do, then just like many bored humans, they may look listless, and, if given the chance, eagerly seek any form of stimulation."
She added: "Many people believe that farm and zoo animals in empty enclosures get bored, but since animals can't tell us how they feel, we can only judge this from seeing how motivated they are for stimulation."
Psychologist Professor Mark Fenske, also from the University of Guelph, pointed out that surprisingly little is known about boredom, despite its association with poor health and lack of well-being.
"Being able to now study boredom in non-human animals is an important step in our efforts to understand its causes and effects and find ways to alleviate boredom-related problems across species," he said.