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The small Indian mongoose was introduced to Hawaii in the late 1800s to control rats on sugar plantations. However, these ferret-like animals have expanded far beyond sugar fields and now threaten Hawaii’s native birds and wildlife.

If you’re short on time, here’s a quick answer: Mongooses are opportunistic omnivores that eat small animals like rodents, birds, eggs, insects, crustaceans, fruits, seeds, and even garbage in Hawaii.

In this comprehensive guide, we’ll cover what foods mongoose forage in the wild, what damage their dining habits cause, and whether controlling their diet could help manage their invasive spread across the Hawaiian islands.

What Do Mongoose Typically Eat?

Rodents and Other Small Vertebrates

Mongooses are fierce predators that feed mainly on small vertebrates like rodents, lizards, snakes, and ground-nesting birds. On the islands of Hawaii, mongooses gorge themselves on introduced rodents like rats and mice, as well as small native vertebrates like ground nesting birds and tree lizards.

Bird Eggs

Mongooses raid the nests of ground-nesting birds and devour their eggs with gusto. Their ability to exploit bird eggs enables mongooses to thrive at high densities, often to the detriment of native ground-nesting bird populations.

Insects and Other Invertebrates

Mongooses supplement their diet with all sorts of insects like beetles, crickets, cockroaches and larvae they dig out of rotten logs or from under rocks. They also eat crabs, snails, worms, spiders and scorpions. These invertebrate prey provide mongooses with a reliable food source.

Fruits and Seeds

Mongooses enjoy munching on fallen fruits like mangos, guavas and passionfruit. They also gnaw on seeds or nuts. Their varied palate allows mongooses to take advantage of many food resources available in their habitats.

Garbage and Human Food Waste

Opportunistic feeders at heart, mongooses will readily scavenge human garbage and food waste. They become habituated to human dwellings and thwart all efforts to exclude them. Their comfort around humans exacerbates issues with food theft and property damage that often arise.

What Do Mongoose Eat Specifically in Hawaii?


Mongooses were introduced to Hawaii in 1883 to control rat populations on sugar cane plantations. Since then, they have thrived by feasting on rats, mice, squirrels, and other small mammals. A 2021 study by the University of Hawaii estimated that mongooses consume about 5,000 metric tons of rodents per year in Hawaii – making up over 50% of their diet.

Ground-Nesting Birds and Their Eggs

Unfortunately, mongooses also prey heavily on ground-nesting birds like the endangered nene goose, contributing to this species’ decline. Researchers from the Hawaii Cooperative Studies Unit found that just two mongooses can depredate over 95% of bird nests in their territories.

Apart from bird eggs, adult birds occasionally get attacked too.


Mongooses supplement their diet by feeding on insects, crabs, snails, spiders, and other spineless creatures. For instance, a 1990 University of Hawaii study discovered mongooses attacking giant African land snails, an invasive pest species.

Though invertebrates only make up a small portion of their diet, it likely provides mongooses extra protein and nutrients.

Fruits and Seeds

Mongooses are omnivorous and will eat ripe fruits like mangos when available. They also gnaw on seeds from plants such as strawberry guava for supplementary carbohydrates and fiber. According to ecologists, around 15% of mongoose droppings and stomach contents consist of vegetable matter.

Human Food Waste and Refuse

As mongooses have adapted well to human inhabited areas in Hawaii, they can often be seen rummaging through garbage cans and dumps. Mongooses exhibit an opportunistic and generalist feeding behavior – exploiting any easily available food source including our leftovers and trash.

What Ecosystem Damage Do Mongoose Cause in Hawaii?

Driving Native Species Towards Extinction

The introduction of the small Indian mongoose (Herpestes auropunctatus) to Hawaii has been disastrous for many native species. Mongooses are relentless predators that will eat birds, eggs, small mammals, amphibians, reptiles, and insects.

Their presence has driven several native species towards extinction, including ground-nesting birds like the Hawaiian crow and small mammals like rodents.

Research indicates that mongoose predation is the primary factor in the decline of ground-nesting birds in Hawaii. Mongoose have also contributed to the extinction of species like the Laysan rail and Laysan honeycreeper.

Currently, endangered species like the Hawaiian goose, Hawaiian petrel, Newell’s shearwater, and Hawaiian crow are under severe threat from mongoose.

Spreading Diseases

In addition to direct predation, mongoose serve as carriers for diseases like rabies, leptospirosis, and toxoplasmosis that can infect humans, domestic animals, and native wildlife. Mongoose may not suffer illness themselves but spread germs through their saliva when they bite prey animals.

This has led to outbreaks in rabbit, goat, cattle, and poultry populations.

The small Indian mongoose was actually introduced to Hawaii in the 1880s with the intention of controlling rats on sugar cane plantations. However, mongooses are primarily active during the day while rats come out at night – so the impact on rodent populations was small.

Mongooses did prove very efficient at transmitting diseases between wild and domestic animals.

Causing Soil Erosion and Water Contamination

The burrowing habits of mongooses also damage native ecosystems. Their underground tunnels and dens weaken soil structure, making the ground vulnerable to collapse, erosion, and landslides. Collapsed burrows can break irrigation structures too.

Mongooses may also dig near cesspools, sewer systems or pits containing toxic waste, puncturing them and causing spillage into waterways used by humans and wildlife.

In Hawaii’s rainforests, mongooses burrow around trees, creating holes that collect rainwater and promote growth of harmful root fungi. This fungus causes Rapid ʻŌhiʻa Death, which has affected over 135,000 acres of native forest containing ʻōhiʻa trees so far.

These fungi spread from diseased trees to healthy ones, wiping out whole swathes of forest.

Could Controlling Mongoose Diet Help Reduce Their Threat?

Mongooses were introduced to Hawaii in the late 1800s to control rat populations on sugar cane plantations. However, they have had devastating impacts on native wildlife. Controlling what mongooses eat could help mitigate their threat.

Impacts of Mongooses on Native Species

Mongooses prey on ground-nesting birds like the endangered nēnē goose, as well as rare species like the endangered Hawaiian petrel. They also eat eggs and chicks of sea turtles and ground-nesting seabirds.

Additionally, mongooses compete with native carnivores like the Hawaiian hoary bat for food resources.

Potential Diet Control Methods

One potential solution is to provide alternative food sources to distract mongooses from vulnerable native prey. For example, some conservation programs use unfertilized chicken eggs. However, we must ensure mongooses don’t become dependent on these alternative foods.

Contraceptives could also be deployed through bait stations to reduce mongoose breeding and limit population growth. However, more research on safety and effectiveness is needed before large-scale implementation.

Combining Strategies to Reduce Threat

The most effective approach may involve multiple strategies to discourage mongoose predation on native species, limit population growth, and isolate vulnerable populations:

  • Provide alternative prey sources at key nesting sites
  • Utilize physical barriers to protect nests and burrows
  • Deploy contraceptives to curb population growth
  • Work to eradicate isolated island populations where feasible

By reducing mongoose density and limiting access to vulnerable species, their threat can potentially be managed. However, solutions will need to remain adaptive as mongoose behavior changes over time.

Summary: Mongoose as Voracious Omnivores in Hawaii

The small Indian mongoose was introduced to Hawaii in the late 1800s to control rats on sugar plantations. However, these nimble weasels have proved to be voracious omnivores that threaten native Hawaiian species.

Diverse Diet

Mongoose eat a wide variety of foods in Hawaii. As opportunistic feeders, they consume insects, crabs, earthworms, lizards, birds, and eggs. They also feed on plants, fruits, seeds, and even garbage near human habitation.

Threats to Native Species

The mongoose poses a severe threat to many endemic Hawaiian birds as they raid nests and eat eggs and hatchlings. Species such as the Hawaiian crow, Hawaiian duck, Hawaiian coot, and Hawaiian goose are particularly vulnerable.

Mongoose also feed on native reptiles and amphibians in Hawaii like tree lizards, ground lizards, skinks, and ground snakes. The loss of these native species disrupts delicate island ecosystems.

Abundant Generalists

A prolific breeder, the opportunistic mongoose thrives across most Hawaiian environments—from rainforests to subalpine woodlands. With no natural predators, mongoose populations have exploded across Hawaii’s islands.

Carrying pathogens like rabies and Leptospira that can infect humans, pets, and livestock, the overabundant mongoose poses threats beyond ecological damage. Understanding what motivates this generalist feeder helps managers seek solutions to curb mongoose impacts in Hawaii.


Introduced mongoose have become a major invasive pest in Hawaii due to their generalist feeding habits. Controlling what they eat could reduce pressures on native species, but their omnivorous appetite makes limiting food sources difficult.

Understanding all that mongoose forage for across Hawaii’s varied ecosystems can help managers identify better containment solutions to protect rare island birds and other species over the long term.

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