Every animal needs an environment where it can survive and thrive. Unfortunately, humans are having a serious impact on the natural world. Our behavior can harm ecosystems and the animals that call them home.
In the 1700s, black rats arrived with humans on tropical islands in the middle of the Indian Ocean. Seabirds play an important role in providing nutrients to coral reefs around these islands. But the invasive rats feed on the seabirds and thus reduce their population. So, the amount of nutrients reaching the coral reefs also decreases.
Coral reef fish need lots of energy from their food to be aggressive and defend their homes from intruders. We thought there might be a connection between black rats, the nutrients available on coral reefs, and the behavior of small reef fishes. Indeed, we discovered that invasive rats on land directly affect the behavior of fish in the sea!