Did you know, there are two types of invasive species? Exotic invasive and native invasive.
Exotic invasive species are species from another area that negatively harm the the ecosystem they are in now. Example: Cane Toads (Rhinella marina) were introduced to Australia in 1935 to try and control beetles in the area. This back-fired and none of the predators in the area could eat the poisonous cane toad.
Native invasive species are species that are found in the area, but for one reason or another have become harmful to the ecosystem. Example: White-tailed Deer (Odocoileus virginianus) in North America. Overpopulation of deer in some areas (more than 20 per square mile) can cause plant decrease from overbrowsing of tree saplings. The high amounts of near are most likely due to the lack of large predators in the area, since wolves and puma/mountain lions are no longer there.
White = Rare/absent/urban area with unknown populations.
Green = < 15 deer per square mile
Yellow = 15-30 deer per square mile
Orange = 30-45 deer per square mile
Red = > 45 deer per square mile