Environmental Impacts

Pigs

Wild boar are destructive due to their rooting behavior, which tears up forest floors, uproots native plants, and creates wallows that become mosquito breeding ground, which contributes to the spread of avian malaria. They also disperse invasive plant seeds and alter watershed functions, leading to erosion and sedimentation in streams.

Goats

The feral Spanish goat thrive in steep, rocky terrain where they overgraze and destroy fragile native vegetation. Their browsing habits eliminate groundcover, leading to rapid erosion and the collapse of native plant communities, especially in dry and coastal ecosystems.

Deer

The Axis and Black-tailed dear are adaptable and reproduce quickly (highly invasive). They graze selectively on native plants and strip bark from trees, which kills or weakens them. Their impact reduces native forest regeneration, increases competition with endangered species, and promotes invasive plant spread.

Sheep

The Mouflon and feral sheep graze heavily on native grasses and shrubs, stripping vegetation from dryland and alpine ecosystems. This leads to soil erosion, reduced plant diversity, and habitat loss for native species like the palila bird, which depends on māmane forests.

Cattle

Cows compact soil with their heavy weight, degrade wetlands and riparian zones, and trample young plants and seedlings. Their grazing pressure favors invasive grasses and leads to nutrient runoff into streams and reefs, harming marine ecosystems.