Invading mole rats found to kidnap pups from conquered colonies

A trio of researchers with Washington University St. Louis, the Columbia River Inter-tribal Fish Commission and San Francisco State University has found that invading mole rats at times kidnap pups from the colonies they conquer. In their paper published in the Journal of Zoology, Stan Braude, Jon Hess and C. Ingram describe their decade-long study of mole rats in Kenya's Meru National Park and what they learned about their efforts to expand colony size.

Prior research has shown that captive mole rats sometimes steal pups from rivals, but such actions have never been seen in the wild. In this new effort, the researchers were conducting a long-term study of mole rats in their native environment. Part of that effort involved capturing and marking multiple specimens from several colonies in the park to learn more about their movements. While conducting this research, they happened to notice one day that pups from one colony had been moved to a new colony, suggesting they had been taken forcefully.

Earlier work by the team had shown that while normally peaceful, mole rats sometimes engage in combat with neighboring colonies. Mole rats can live in colonies with populations reaching 300 individuals. Such colonies are populated with workers and queens who produce the workers. But now, it appears the mole rats are not above stealing pups from other colonies to boost their numbers. Prior research has also shown that larger colonies tend to fare better in the wild.

After the discovery of foreign pups in a colony, the researchers began watching the action more closely when one colony invaded another. They found it was almost always a large colony invading a much smaller colony, ensuring success. The colony being invaded tended to yield without putting up much of a fight, retreating to a more distant part of their nest, or in other instances, abandoning their nest altogether. In either case, the researchers observed several instances of pups being captured and raised as workers in the conquering colony. They note that their observation techniques are still limited to the extent that observing these few instances of kidnapping likely suggests it is a common occurrence.

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