October 15th, 2023
While driving our small electric vehicle out in the valley to check on wildlife cameras, my colleague Rob and I observed a small mammal in the narrow grassy roadway. It was instant recognition because I had seen the same creature in my garden earlier in the summer. This was a Broad-footed mole, Scapanus latimanus. It was dead but looked unharmed and in perfect shape. The soft fur is delightful to touch. Its body is a shiny grey and its belly is a lighter silver color, while its tail is short and slightly hairy.
I have found at least a half dozen of these interesting animals, and all but two were dead like this one, with no sign of what had killed them. Moles belong to the family Talpidae. They are small insectivorous mammals that evolved the ability to dig and live underground.
The Talpidae are a diverse and widespread group in North America, ranging from the tiny Shrew mole of the Pacific Northwest to the bizarre, semi-aquatic Star-nosed mole of New England. According to the textbook Wild Mammals of North America by J. A. Chapman and G. A. Feldhamer, moles are probably the least understood major component of the North American mammalian fauna. The Broad-footed mole is endemic to the United States with a recent split into three separate subspecies. The Northern Broad-footed mole, Scapanus latimanus, the Southern Broad-footed mole, Scapanus occultus, and the Mexico Broad-footed mole, Scapanus anthonyl.
Northern Broad-footed moles have large flat front feet, placed close to their head, which is where their name comes from. They are super adapted for their burrowing and fossorial life, their bodies are streamlined with no external ears, and both front and back feet are short and remain close to their body. The front feet are broader than they are long, and their terminal phalanges are divided which also helps with digging. The front feet are so close to the head that the moles appear to be “neckless.” The nails, or claws, on the broad front feet are extraordinarily large, comprising 50% of the total length of the hand. The back feet are quite reduced along with the bones in the pelvis area. This decreases drag when burrowing through the soil. Even the mole’s eyes and fur are adapted for the subterranean lifestyle. Their eyes are tiny and out of the way, while their fur has a structure specific for easy forward and backward movement. This allows them to be able to move rapidly through the ground, as if swimming through the dirt. They have been clocked tunneling at 15 feet per hour and in favorable areas 12 inches per minute! Digging activity is most often observed when the soil is soft and friable, during the fall and winter.
These large moles are found in a variety of habitats that contain moist loose soil including urban gardens, grasslands, wet meadows, pastures, montane and valley foothill riparian, cropland, vineyard-orchards, and forests. Moles are solitary and territorial animals, constantly patrolling and defending their burrow systems. These tunnels are typically far below the surface level with the excess earth pushed out laterally and then vertically up shafts that create distinctive volcano-shaped mounds. Shallow surface tunnels are sometimes dug which form a long ridge in the soil. These are used irregularly for unknown purposes according to my research. Since earthworms and grubs are one of their main food sources, maybe these are hunting tunnels? They also eat other invertebrates and a small amount of plant material.
The breeding habits amongst Broad-footed moles are not well documented, but the breeding season is from February to March depending on the climate. This is the only time of the year that multiple male moles can be found in a female mole’s resident tunnel. After breeding, the males go back to their solitary life in their own burrows. A male mole is called a boar, and a female mole is called a sow. They have three to five young pups that spend 30 to 35 days in the nest nursing before dispersing.
Moles play an important ecological role in many wetland and grassland ecosystems where they live. They provide food for local predators such as owls, hawks, and snakes. According to the California Department of Fish and Wildlife, their strong and musky odor may make them unpalatable for most mammalian predators, however coyotes and raccoons do dig them up and may resort to eating them out of hunger! Other important ecosystem functions moles have is that they eat many insect pests in the soil and provide aeration for the roots of plants. Look for small volcano-shaped mounds in your yard to see if you have a Northern Broad-footed mole living near you.