10 Oddly Helpful Invasive Species

Invasive species are often thought of as doing nothing but damage to the ecosystems they come to inhabit. Although some invasive species are indeed causing a great deal of destruction, there are examples of nonnative species being introduced into an ecosystem and doing some good. Who knew, right?

It seems that several species have even  contributed to saving an endangered species. Are you curious? Just scroll down and find out more!

10. European Green Crabs And The Salt Marshes Of New England

The European green crab is generally considered one of the most hated of all the invasive species, as it is known to be quite aggressive, eating just about everything it comes across. European green crabs have colonized coasts all over the world, but they have had a surprisingly positive impact in the New England area. Here, overfished salt marshes saw the cordgrass (Spartina alterniflora) nearly eliminated by marsh crabs, a native species of crab. With the arrival of the green crab, however, the marshes began to recover.

9. Spartina Grass And The California Clapper Rail

The California clapper rail, an endangered bird species that resides solely in the San Francisco Bay, has taken to nesting in Spartina grass, an invasive species that is at least partially responsible for the eradication of the birds’ habitat. Urban development is the other influencing factor behind the loss of habitat, but the birds have not taken to nesting in the concrete jungle that has encroached on their home. Instead, they have adapted and are now using the invasive grass species as a nesting place.

8. Japanese White-Eye And Hawaiian Flowers

The Japanese white-eye, a bird that was brought from Japan to Hawaii in the late 1920s, was initially transported to help control the bug population. The birds quickly spread, and the white-eye is now the most common bird found on the Hawaiian Islands. As other native birds have gone extinct—a decline that is often attributed to the Japanese white-eye’s overwhelming dominance of the islands—many flowering plants have become “widowed” due to the extinction of the pollinating birds. The Japanese white-eye is filling in the gap, pollinating at least two flowering plants that have otherwise been widowed by the extinction of the native birds.

7. Tamarisk Shrubs And Southwestern Willow Flycatcher Nests

The plight of the southwestern willow flycatcher is the result of so many unintended consequences caused by the repeated efforts of the US government that it borders on comical. Tamarisk trees, also known as salt-cedar shrubs, are an invasive species that were intentionally introduced to the United States to control soil erosion through their large capacity for water consumption. After some time, however, it became clear that the water the tamarisk was consuming was draining riverbanks and destroying the willow trees that the southwestern willow flycatcher used for nesting.

With its natural nesting place limited significantly by the invasive tamarisk trees, the endangered species of bird adapted and began using the tamarisk trees as a place to nest.

6. Aldabra Tortoises And The Ebony Trees Of Mauritius

When introducing an invasive species, it certainly helps if it is an extremely close relative of the species whose function it is replacing. This was the case with the Aldabra tortoises that were introduced to the island of Ile aux Aigrettes on a very small scale, starting back in 2000. The massive tortoises—adults frequently check in at 300 kilograms (660 lb)—were brought in with the hope that they could help in the restoration of the island’s endangered ebony forest. Many of the ebony trees had been harvested for firewood, and new growth had been extremely limited.

The nonnative tortoises are eating the fruit produced by the ebony trees and dispersing their seeds all over the island. Over a decade after the Aldabra tortoises were introduced, researchers are noting that the endangered ebony forests are beginning to recover.

5. Yellow-Crowned Night Herons In Bermuda

When the island territory of Bermuda was colonized hundreds of years ago, Bermuda night herons were among the original residents. They quickly became extinct due to the introduction of new predators that fed on the terrestrial birds, along with the fact that humans found the herons “so familiar and tame” that they were easily killed with “stones and staves.”

In the late 1970s, yellow-crowned night heron, a relative of the extinct Bermuda night heron, was introduced from Florida to the island as a biological control for the overabundant land crabs. The strategy was a success, and the invasive yellow-crowned night herons now enjoy a self-sustaining population on the island and continue to rely on land crabs for 95 percent of their diet.

4. Zebra Mussels And The Great Lakes

There is a lot of criticism heaped at the invasive zebra mussels that inhabit the Great Lakes, and much of that criticism is richly deserved. The mussels are able to spread rapidly and densely, frequently covering everything that they are able to attach themselves to. They have also affected the ecosystem of the waters they invaded by competing with many native species of mussels for food. Some of those species of mussels are already considered endangered.

However, the waters inhabited by the zebra mussels have been linked to increased health of the salmon population and to improved water clarity. Lake Ontario has benefited in particular, as its visibility has been significantly improved by the presence of the water-filtering zebra mussel.

3. Multiple Invasive Tree Species And Abandoned Agricultural Land In Puerto Rico

The effects of over-farming a plot of land are firmly established, as soil erosion and compaction often result from unsustainable agricultural practices. In Puerto Rico, many of these degraded plots of land were abandoned, and the native species of trees endemic to Puerto Rico were unable to return to these areas. A number of invasive tree species—including the white siris, the African tulip tree, the rose apple, and many others—have demonstrated that they are able to take over these abandoned agricultural fields in spite of the poor soil conditions.

However, the fact that these trees survive in the degraded agricultural areas is not the most significant—these trees are also crucial to enabling the eventual return of the native tree species. It appears that the initial thriving of the nonnative species eventually leads to native trees being able to grow in the understories.

2. California Butterflies, Yellow Star Thistle & Eucalyptus Trees

There are many invasive plant species in California, many of which have been planted for ornamental purposes by well-intentioned Californians. While some of these invasive plants have proved to be toxic to at least three species of butterflies that lay their eggs on them, there are numerous examples of butterflies in California benefiting from the presence of invasive plant species.

The yellow star thistle, an invasive weed that is reviled throughout the state of California, has become an important resource for many native butterflies in California’s Central Valley. The yellow star thistle provides these foothill butterflies with a source of nectar that is widely available and easily accessible.

1. Honeybees In North America

The honeybee has become so part and parcel to the North American ecosystem that it is easy to forget that it is a nonnative species. The European settlers who migrated to North America in the 1600s brought the honeybees with them. The arrival of the honeybee was so closely associated with the arrival of the Europeans that Native Americans referred to the bees as the “white man’s flies.”

Now that the survival of the honeybee is threatened in North America by colony collapse syndrome, industrial agriculture, mites, and deforestation, there is great concern over how the loss of the honeybee will affect an ecosystem that has come to rely on it for pollinating a wide variety of plant life.

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