Invasive Species in Madagascar
The plants and animals in Madagascar evolved in isolation, creating unique ecosystems with species found nowhere else in the world. When non-native species enter these ecosystems, they can put them — and the plants and animals that live in them — in danger.
How do exotic (non-native) species affect wild ecosystems?
First, let’s clarify some scientific terms so we all understand the concept of invasive species. All invasive species are exotic, but not all exotic species are invasive. What is the difference between exotic and invasive species?
- Exotic Species: a species that is introduced and that becomes established in an area where it never previously occurred
- Invasive Species: an exotic species that has a negative impact on native species in an area
Negative impacts from invasive species can be even more drastic in ecosystems with a high number of endemic species like Madagascar.
Invasive species in Madagascar
The invasive species found in Madagascar were introduced by humans, and they may surprise you.
Rats, stray dogs, and stray cats in Madagascar are all considered invasive species in Madagascar. They often live in or enter parks and other conservation areas. Besides carrying potentially harmful diseases, these invasive species can also prey on the natural wildlife of an area, including lemurs. So, while we may think of the fossa as the lemur’s most likely predator, often stray dogs and cats can be a bigger threat to wild lemur populations.
Additionally, sometimes exotic animal species enter Madagascar accidentally in large cargo ships at shipping ports like Toamasina on the east coast. If the species are not contained immediately, they can enter the ecosystem and put the balance of wildlife in danger. Learn about an invasive toxic toad that entered Madagascar through a shipping port.
It’s not just animals that can be invasive species. Reforestation with non-native plant species like pine and eucalyptus can encroach on primary and secondary forests. This often degrades habitat and can even cause habitat fragmentation. Fragmentation is dangerous because it isolates lemur populations so they can’t travel between groups. This can result in lower genetic diversity and lemur populations that are less healthy.
While many reforestation efforts in Madagascar are careful to use non-invasive plants and trees, some don’t. And some past reforestation efforts, especially those during the French colonial period, used non-native species like pine. In Ranomafana National Park, pine trees are now encroaching on the park boundaries. While reforestation is very much needed in Madagascar, we must be careful to do it right. Learn about the importance of well-planned reforestation efforts.