European Buckthorn: Junk Food for Wildlife

Common buckthorn

Like humans, Mother Nature has to deal with the consequences of junk food. The spread of invasive plant species in the Credit River Watershed creates big problems for plants and wildlife. When non-native plants like European buckthorn (Rhamnus cathartica) enter a natural area, they often take over and harm native plant species.

Seeds from common forest species like sugar maples, large-leaved aster and purple meadow-rue have a hard time budding when covered by buckthorn leaves. This is because of a process called allelopathy. Buckthorn fights against other plants to secure its own place in the ecosystem, and it can change soil properties like pH and nutrient levels.

Buckthorn is also harmful to wildlife. Songbird species like the American robin and cedar waxwing rely on fruits from trees and shrubs to feed their offspring in the summer and fuel-up for fall migration. When invasive species like buckthorn are introduced to an area, they provide a resource for birds with lower nutritional value than the fruit from native species that are displaced.

Birds must then spend more time and energy searching for non-native berries to fuel themselves and their young. It also makes storing enough fat to fly long distances more difficult, possibly hurting a bird’s chances of surviving migration.

American robin, photo credit: Jon Clayton
American robin, photo credit: Jon Clayton

Songbirds like warblers, flycatchers and vireos enjoy dining on insects. Areas overrun by invasive plants have fewer insects and diversity, reducing resources for songbirds.

Even insects have a sweet tooth. A recent study showed that benthic macroinvertebrates (insects and other organisms that live on a stream bottom) suffer when buckthorn invades their local environment. The study looked at food preferences among native scuds, a crustacean like small shrimp that feed on fallen leaves. When given the option of non-native buckthorn leaves or native ash tree leaves, scuds overwhelmingly preferred buckthorn. Scuds fed buckthorn leaves were smaller and had a higher mortality rate than those fed native ash leaves. Not to mention is rotted their teeth!

A scud from CVC’s lab
A scud from CVC’s lab

Interested in learning about how CVC helps control invasive species? Do you want to know how you can help? Check out our invasive species page.

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