The migration of a species to a new area is called "invasion" or more specifically, "biological invasion." This process occurs when a species expands its territorial range beyond its native habitat, often into ecosystems where it has not existed before. Biological invasions can occur naturally or as a result of human activity, including the introduction of species for agricultural purposes or accidental transfers via shipping and trade. These invaders can significantly impact native species, ecosystems, and biodiversity, sometimes leading to the decline or extinction of local species as they compete for resources.