Ecologist Mary Price of the University of California-Riverside and theoretical biologist John Mitter of the University of Washington explored a hunch that the puzzling coexistence might follow from the propensity of the rodents to store harvested seeds and then to steal from one another’s caches.

I gave up on traditional explanations when we couldn’t find size-related tradeoffs in foraging rates or predator avoidance under different environmental conditions said Price, who has spent more than 20 years exploring niche-partitioning explanations for the remarkable diversity of desert rodent communities. I always had a suspicion that caching was important because heteromyids are so obsessive about it.

Using resource-processing models of coexistence in which feeding by one species creates a modified resource another can use, the researchers found thievery actually promotes stable coexistence if one species excels at harvesting while the other excels at stealing.

We can’t conserve biodiversity if we don’t understand the processes that maintain it, Price said.

The researchers say they expect their findings will suggest new ways to preserve species diversity.