Do you realize you probably walked on someone’s roof today?
While we humans spend our days walking on top of the ground, many mammals spend their days and nights in burrows and digging underground.
When you walk across your yard, the park and sometimes even sidewalks you are often walking on the roof of an underground mammal.
Animals that burrow underground are called “fossorial.” A life underground might not seem that enticing to most of us humans, but the world of burrows has a ton of benefits for the mammals that live there.
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Living underground helps keep them safe from predators. Hot, cold, snowy, rainy and other weather conditions do not apply when you live a life in the soil where the temperature is pretty constant in your snug burrow.
There is lots of food underground if you are fond of roots, shoots and invertebrates. Burrows also are a great place to hide if you’re looking to ambush your prey or even to hibernate for a while.
While we pass by (and over) them every day, we typically don’t think much about the mammals living underground, but these burrows are vitally important to the ecosystems they inhabit.
Mammal burrows provide incredibly important habitat for other species of animals that can’t dig their own burrows. Snakes, lizards and other reptiles often use burrows dug by mammals, as do amphibians such as newts.
Lots of invertebrates, such as spiders and beetles, use these tunnels and mice, rabbits, weasels and other small mammals will occupy abandoned tunnel systems dug by others as well.
In addition to providing habitat for other animal species, digging mammals help aerate and fertilize the soil, which improves growing conditions for plants.
One pocket gopher can move more than two tons of soil to the surface in a year, so their digging has tremendous benefits to the environment, especially where soil tends to become compacted. Plant communities are more diverse and productive where burrowing mammals live their lives.
One of the most common burrowing mammal groups in the Tacoma area is one of the most secretive — moles.
We have nine species of moles in Washington State, three of which live in our area.
In fact, we live among Townsend’s moles, the largest moles in North America at almost 9 inches long, and shrew moles, the smallest moles in North America and no bigger than your thumb.
Moles are not rodents like mice or squirrels. Moles are mostly insectivores, meaning they eat mostly insects and other invertebrates. Earthworms, crickets, beetles, spiders, snails and slugs are all important foods for our local moles.
Moles are nature’s “pest” control, eating many of the animals that like to eat our gardens and crops. They have long, pointed noses, sharp teeth and the ability to subdue and eat small animals.
Moles are highly adapted to live their entire lives below ground. They have enlarged, flat front feet with claws that are efficient for digging. Their fur is aligned so hey can move forward and backward in a tunnel without any resistance in either direction.
Moles can live in environments with lower levels of oxygen and higher levels of carbon dioxide than most mammals. Their eyes and ears are very small, as these senses are not as useful underground as they are to species that live above ground.
Instead they have a keen sense of smell and sensory hairs on their bodies that help them move through their world, find their mates and identify food in the dark.
There even is a species called the star-nosed mole that has a nose with several “arms” that is a very finely tuned sensory organ. Fun fact: the star-nosed mole is the one of the fastest known eaters in the world, gobbling up a worm in a quarter of a second.
Most people tend the think of underground mammals as just having tunnels, but the mole burrows we walk across can be quite complex.
There are tunnels to and from foraging and nest areas and many have special nooks and tunnels for drainage, multiple “bedrooms,” emergency exits, nurseries, pantries and bathrooms.
They have to dig every room in their lodgings and maintain the tunnels so they do not collapse.
Mammals like moles that live underground are hard to study but we can still explore their worlds. If you look down and know what to look for, you will see their sign all over.
Moles have shallow tunnels that show up as linear, raised areas of soil that are often easily seen from above. They also make “mole hills,” which are symmetrical mounds of soil that they push up while they are digging tunnels.
The next time you are on a trail or in the park keep an eye open for signs of recent mole digging, especially in shaded or other areas with moist soil. Moles get dehydrated easily so they tend to live in humid environments.
Kids can explore the world of underground mammals by creating their own tunnel systems.
Using small cardboard boxes, paper towel tubes and some imagination they can create their own tunnel systems at home. What rooms would you need to live your entire life underground? How would you arrange your underground world?
If you have large cardboard boxes, you can make a tunnel system in the yard that you can crawl through and pretend to be a mole.
There are exhibits of naked mole rats that you can explore at places such as the Point Defiance Zoo in Tacoma and the Pacific Science Center in Seattle.
While naked mole rats are not closely related to moles, the organization of their tunnels and rooms are similar to those of moles.
So as you walk past mountains and mole hills today, think about all the hard work happening beneath your feet and tip your hat to our neighbors the underground engineers.