By David Mizejewski, National Wildlife Federation Naturalist
As we head into autumn, many trees and shrubs shed their leaves or needles in preparation for their winter dormancy. The standard practice is to rake up or blow away all the leaves and bag them for the trash — but doing so causes pollution and further disconnects our cities, towns and neighborhoods from the local ecosystem. It also hurts wildlife.
Fallen leaves are important habitat for many species of wildlife. Photo: Maria Swanenburg via National Wildlife Federation.
What do fallen leaves have to do with wildlife? Turns out the fallen leaf layer that forms each autumn as plants drop their foliage is an incredibly important habitat for many kinds of wildlife.
To bring awareness to the importance of leaves for wildlife, the National Wildlife Federation has designated October as Leave the Leaves Month. Learn about five types of animals that rely on leaves.
Five types of wildlife that benefit from leaves
Butterflies and moths
Butterflies and moths start their lives as caterpillars. While winged adults feed on flower nectar, their caterpillars feed on the leaves of plants. Each species has different types of host plants that their caterpillars eat until it’s time to pupate (a step in their life cycle). This is where fallen leaves become important.
Many of these species spend the winter months as pupae in the leaf layer beneath the trees where they fed as caterpillars. Some species spend the winter in the fallen leaves as caterpillars or adults too. For moths, a whopping 94% of species rely on the leaf layer to complete their life cycle.
Luna moths spend winters as pupae in the leaf layer. Without leaves, they cannot complete their life cycle. Photo: Alan Schroeder via National Wildlife Federation.
Some species, such as the seafoam green luna moth, incorporate fallen leaves into their actual cocoon when they pupate. Others, such as the vivid tiger swallowtail butterfly, form chrysalises that resemble dead leaves for camouflage in the winter leaf layer. Red-banded hairstreak butterfly caterpillars even feed on dead leaves and mourning cloak butterflies spend the winter in the leaves as adults.
If you remove all the leaves that fall in autumn, you wipe out whole generations of these insects, most of which are pollinators and all of which are important parts of the food web.
Birds
Most songbirds, such as this immature Kirtland’s warbler, rely on caterpillars of moths and butterflies as a critical food source. Photo by Matt Felperin via National Wildlife Federation.
Did you know that 96% of our backyard birds include insects and other invertebrates in their diet? And that those invertebrates are the only food source for their babies in the spring? Without insects, spiders, earthworms and other creatures, birds cannot survive.
Where do many of these invertebrates live? In the fallen leaf layer. Caterpillars of butterflies and especially moths are an absolutely critical food source for baby birds. Many butterflies and moths cannot complete their life cycle without the leaf layer. When you get rid of all of your leaves, you not only decimate butterfly and moth populations, you wipe out the main food source for next year’s baby birds. Plus, some birds even nest in the leaf layer, including veeries, ovenbirds and northern bobwhites.
Salamanders
Salamanders, such as this red eft, live in the leaf layer. Photo: William Borne via National Wildlife Federation.
As amphibians, salamanders have special skin through which they absorb oxygen and liquids. If they dry out, they can die. The fallen leaf layer is a naturally moist environment and as a result many salamander species rely on it as their primary habitat.
Salamanders and other amphibians are globally disappearing faster than any other group of vertebrate wildlife. One-third of all species is endangered — so anything we can do on the local level to make sure these cute and often colorful animals have habitat is important. Leaving a natural layer of leaves in your yard is a simple way to do that.
Chipmunks
Chipmunks rely on the leaf layer for food and shelter. Photo: Diane Spray via National Wildlife Federation.
Who doesn’t love the adorable chubby cheeks of a chipmunk? There are several species of these tiny striped squirrels found across North America, but they all utilize the leaf layer as their habitat.
Like other types of squirrels, chipmunks love acorns and other nuts, but they are also surprisingly carnivorous. Chipmunk diets include insects, snails and all sorts of other invertebrates, as well as their fellow leaf layer inhabitants, salamanders and even young mice.
With their brown, tan and black-striped fur, they’re also perfectly camouflaged in the leaf layer, which helps them from becoming a meal themselves to foxes, hawks and other predators. Watching the scurrying antics of your chirping chipmunk neighbors is a nice reward for cultivating a leaf layer in your yard.
Turtles
An eastern box turtle feeds in the leaf layer and survives winter by burying beneath it. Photo: Jenni Lopez via National Wildlife Federation.
Box turtles are a beloved reptile that sometimes shares our neighborhood. These woodland turtles don’t live in ponds. Their home is the leaf layer.
Box turtles are omnivores, feeding on everything from berries and mushrooms to worms and insects, all of which can be found in the leaf layer. The rapidly disappearing wood turtle also relies on woodlands with a healthy leaf layer as part of its habitat.
Like all reptiles, turtles are ectothermic or cold-blooded animals whose body temperatures are dictated by their environment. Unprotected exposure to freezing temperatures will kill them. When the weather turns cold, they escape by burying themselves and going dormant. Box turtles do this by digging themselves into the top layer of soil beneath the leaf layer. The leaves provide critical insulation for these charismatic creatures and they wouldn’t survive the winter without them.
Saving your fallen leaves is just one way to help wildlife in your backyard. Get Naturalist David Mizejewski’s garden for wildlife how-to book, Attracting Birds, Butterflies and Other Backyard Wildlife, to learn more.
Plus, save these tips on how to grow your garden to attract wildlife.
Don’t have your own backyard? No sweat! Discover wildlife in urban places.
