Four common birch species can be found in North America, and all create a habitat in and around them that is used by many different types of wildlife, such as insects, small mammals, and birds. I wanted to learn more about what we can see walking through a birch wood.
Insects, birds, mammals, and fungi can be found in beech woods. Aphids grow on leaves, while caterpillars feed on the leaves. Birds feed on the numerous insects that the trees attract and use the softwood to nest. Fungi have a symbiotic or parasitic relationship with birch trees.
Birch is one of my favorite-looking trees, and I was impressed by how much wildlife they attract. If you want to find out more, please read on.
Birch form extensive woodlands in a variety of habitats. Birch is well adapted to living in harsh climates and poor soils. Birch spread their seeds on the wind and can colonize a new area quickly.
Birch are attractive trees, especially when their trunks gleam in the winter sun. During spring, they come alive with color with new green leaves and catkins, and in fall, their brown and yellow leaves are some of the most colorful.
North America’s four main birch species are paper birch, river birch, yellow birch, and sweet birch. The yellow birch is the largest, growing up to 100 feet tall, while the paper birch is the smallest, growing up to 60 feet tall.
Birch spread their seed using the wind. They can be recognized by the tiny, paper-winged sources that can be seen floating down and on the ground. The seeds are carried on their wings for great distances to reach new areas. Birch is a hardy plant; even as a seed, it will take over any open ground they land on.
Birches quickly grow, with a two-year-old tree standing a couple of meters high. After about a dozen years, the birch will reach maturity, sending its seeds on the wind to germinate. Birch can live up to 100 years, although 60-70 is the most common.
Birches will grow even if there are grazing animals, such as rabbits and deer, in the area, as they are not well-liked by these animals. However, when there is nothing left to eat in the winter, they will eat the birch trees.
If oak or conifer trees have been felled and not replanted, birches will soon take their place, growing thin and tall together.
Insects are attracted to the paper beech due to its bark. The bark cracks and peels as the tree ages, with fissures near the base. These make excellent hiding places for many insects, including ants, beetles, and centipedes.
Birchwoods allow a dense undergrowth to grow in the birch’s light, even in the whole leaf. Birch can grow in different soils. In poor soils, the undergrowth may consist almost of bracken, allowing many insects and small mammals to live undisturbed. In damper soils, birchwoods will give rise to beautiful woodland flowers such as bluebells and primroses.
If the soil is sandy, such as around heathlands, the undergrowth will contain typical heathland plants such as heathers, gorse, and wavy-hair grass.
Many fungi live in birch woods, and the fungus usually stops the trees from reaching full maturity. More fungus will appear as the branches die back and the heartwood rots.
The birch polypore, also known as the birch bracket, grows on the trunk of birch trees and is the most common fungus. The fungus has a hard, smooth, brown, leathery surface with no stalks. The fungus has a white, porous underside. The spores are released from the bottom by the breeze.
A tiny beetle can sometimes be found below the fungus’s surface, staining the white tissues pink. The beetles and the fungus leave the wood very soft, allowing woodpeckers and other hole-nesting species to be nesting sites.
Wrinkled crust fungus looks like a lichen, appearing as orange patches on birch trees, and is commonly found on dead birch trees.
The fly agaric, the most recognizable toadstool, can be found below birches in the fall. These benefit the trees as they form an association with the roots of the birch. The tree uses materials extracted by the fungus from the soil—the fungus benefits by receiving the tree’s nutrients. Although the birch tree does not need the fly agaric to survive, the fungi must always have birch trees nearby to survive.
There are many other types of fungi living that you can find around beech trees. The brown bolete, milk caps, and russulas are some fungi that can be found. Some are poisonous, so don’t eat them.
Some fungi live in harmony with the tree, living alongside them peacefully, while others are parasites and will take all the nutrients from the living wood.
Woodpeckers can often be seen around birch trees as birch has a soft texture and a thin bark. Woodpeckers can quickly make holes for feeding in living trees, and dead trees often make larger holes to build their nests.
Fungus on birch is also a good indicator of finding other animals. If the birch bracket fungus grows from a birch tree, the wood is usually soft enough for woodpeckers to nest in a hole. If the birch is old and no fungus is growing, then woodpeckers may be seen drumming on them, as these make a noise that will travel far.
Birch woods are ideal for many birds as the trees are generally close to each other and harbor many insects. Finches will feed on the seeds found in the cone-line catkins. Golden-crowned kinglets, siskins, and titmice can often be seen fighting with flocks of finches for seeds on birch trees.
Not only the bark, the trunks and the seeds bring wildlife to birth trees. Many insects, such as aphids, live on birch leaves’ underside and can be found when the leaves first open at the beginning of the season. These provide a valuable food source for many birds, which may nest around the birch scrub or brambles nearby.
The second hatch of aphids later in the season provides more food for birds preparing for migration. Caterpillars of butterflies and moths will also feed on birch leaves, although many of these end up as food for birds.
Bryan Harding is a member of the American Society of Mammalogists and a member of the American Birding Association. Bryan is especially fond of mammals and has studied and worked with them around the world. Bryan serves as owner, writer, and publisher of North American Nature.