Ungulates of Hawaiʻi

Feral pigs (Sus scrofa)

Range: Hawaiʻi island, Maui, Molokaʻi, Oʻahu, Kauaʻi

Region of origin: Eurasia

Date of first introduction: 1000 to 1200 AD (arrival of Polynesians)

Average size: 45 kg to 70 kg

Litter frequency: 1 to 2 litters per year

Litter size: 5 to 6 piglets

Home range: 0.11 km to 0.86 km (Hawaii); 0.3 km to 2.1 km

(New Zealand); 4.6 km to 6.1 km (Mainland US)

Diet: Tree ferns, fruits, earthworms, small vertebrates

2

References: Tomich 1986, Salbosa and Lepczyk 2009, Wehr et al. 2018, Duffy

and Lepcyzk 2021

Identifying Markers

Physical Appearance: Coarse bristle hair, usually black, dark brown, or grey (sometimes mottled), medium to large in size (100–200+ lbs), with short upright or semi-floppy ears, a long flat snout, and a curved tusk (in males).

Tracks: Four-toed cloven hoof prints, about 2–3 inches long.

Scat: Droppings are tubular, segmented in piles, dark in color, and full of undigested seeds, fibers, or vegetation.

Rooting Damage: Appears as disturbed ground, often several inches deep, in irregular patches (common in forests, lawns, taro patches, and pastures).

Wallowing Pits: Shallow muddy depressions where pigs roll to cool off and deter parasites, often found near water sources (streams, seeps).

Environmental Impacts

Wild boar are highly destructive to Hawaiʻi’s ecosystems due to their rooting behavior, which tears up forest floors, uproots native plants, and disrupts soil structure. This activity creates open ground that invites invasive species and eliminates habitat for native understory plants and ground-nesting birds. Their wallowing behavior forms muddy depressions that collect standing water, providing ideal breeding grounds for mosquitoes, which increases the spread of avian malaria—a major threat to Hawaiʻi’s native forest birds. Wild boar also consume and disperse seeds of invasive plants, accelerating their spread.