Moles are one of the most common mammals in many parts of the worldScientific findings are awaiting discovery in your backyard. The requirement? A keen sense of observation and patience.

Vladimir Dinets, a University of Tennessee, Knoxville, research assistant professor of psychology, recently completed a study on moles' behavior that proves the concept. His laboratory? A molehill-dotted city lawn in downtown Chico, California.


He has discovered that broad-footed moles, which are typically difficult to observe, feed on the ground quite often but only on cool, wet nights with fog or rain. On such nights, the leaf litter is wet and does not make much noise, which allows the moles to move around without attracting predators.

The finding was recently published in the journal Mammalia.

"This surprising find shows that there are still lots of interesting discoveries to be made literally in your backyard," Dinets said. "All it takes is being observant and patient, and knowing what to make of what you see."

Moles are one of the most common mammals in many parts of the world, including both coasts of the United States. But they are difficult to observe and, like that of many seemingly familiar animals, their behavior in the wild is almost unknown. For centuries, many believed most species of moles, including five of seven North American ones, are strictly fossorial—meaning they spend their entire lives underground. The only exception was thought to be young animals that have to leave their mother's tunnel system to find a place where they can dig their own.

Although there were a few observations of adult moles, particularly of the better-studied European mole, feeding on the surface or being consumed by terrestrial predators such as owls, these records were largely ignored by zoology textbooks.

Dinets spent many years trying to observe so-called cryptic animals — those considered difficult to see and study — in their natural habitats. He occasionally saw moles on the surface that seemed to be adults actively looking for food such as insects and worms, rather than juveniles. He posted a request for similar observations on, a website for amateur mammalogists comparable to birdwatching websites, and received a few more such reports. It became increasingly clear that even those species of moles that are considered strictly subterranean are not that strict about staying underground.

To discover how often they get out, Dinets spent two months watching the California molehills. He found that broad-footed moles, the species occurring over much of California, feed on the ground quite often in the cool, wet nights. This nocturnal foraging makes surface-active moles extremely difficult to observe for humans, which in part explains why that behavior has remained unknown for so long.

As soon as the spring rains end and the hot California summer sets in, the moles move to deeper tunnels and stop leaving their underground networks altogether.

"This is surprising because European moles do the opposite: they are more often found on the surface at the time of extreme drought," Dinets said.

Moles have independently evolved three times, he said. Moles of Eurasia and North America are closely related to shrews, while very similar-looking moles of Africa are distant relatives of elephants, aardvarks and manatees. There are also marsupial moles in Australia. Many mole species are among the least-known mammals, but occasional records scattered in old literature and mammal-watching reports suggest that all of them, even species with eyes covered with skin, forage on the surface at least occasionally. There is no such thing as a strictly fossorial mole.

Dinets noted that even with all precautions that moles take, such as moving very quietly and staying under dense cover of vegetation, they often get caught by predators while roaming above ground.

"They probably keep doing it because this behavior provides a critically important backup strategy at the time of food shortage, and also because moving on surface takes much less energy than digging through the soil," he said.