No native mammalian predators leave local terrestrial creatures defenceless. Feral cats are voracious murderers. They murder without eating, making them scarce.
Feral cats
Most Hawaiian birds nest on the ground, making their eggs mongoose food. Mongooses have little impact on rat populations but devastate local bird populations.
Mongoose
Pigs ruin plant life and consume bird eggs, destroying native habitats. Feral pigs are a nuisance and have no natural predators save humans.
Wild Boar
They are native to Australia, Indonesia, and Papua New Guinea. They eat birds, lizards, bats, and mice. They're an invasive species in Hawaii and the Pacific.
Brown Tree Snake
Tens of thousands of deer inhabit islands without local predators. They affect native plant life and bird populations by destroying nesting places.
Axis Deer
These chameleons feed native insects, yet they have no predators in Hawaii. Brown tree snakes eat them. They could help brown tree snakes colonise Hawaii.
Jackson’s Chameleons
Rats eat most of Hawaii's ground-nesting birds. No land predators meant no tree nesting. Rats destroyed bird populations.