Exploring the History and Impact of Kiore Pacific Rats in New Zealand

The Kiore Pacific rats (Rattus exulans) hold a unique place in the biological and cultural history of Aotearoa New Zealand. Unlike the later-arriving European rodents, these small mammals were intentional travelers, brought across the vast Pacific Ocean by the ancestors of the Māori.

I. Origins and Arrival with Polynesian Voyagers

The story of the Kiore Pacific rats begins in Southeast Asia, spreading throughout the Pacific islands alongside human migration. When Polynesian navigators discovered New Zealand around 1250–1300 AD, the Kiore were part of the cargo.

Kiore Pacific rats begins in Southeast Asia

They were not merely "stowaways"; these rats were a significant source of protein and a valued resource. Because they cannot swim long distances, their presence on offshore islands across the Pacific is a definitive marker of human seafaring routes.

II. Physical Characteristics and Behavior

Kiore are the third most widespread rat species in the world, yet they are smaller than the brown or black rats introduced later by Europeans.

• Appearance: They possess a brown coat, a white underbelly, and distinctive dark patches on the outer edge of their hind paws.

• Size: Adults typically weigh between 60 to 80 grams.

• Diet: Being omnivorous, they consume a variety of seeds, fruits, insects, and small lizards.

Physical Characteristics and Behavior

III. Cultural Significance to Māori

In traditional Māori society, the Kiore was viewed very differently from modern pests. They were protected by specific tapu (sacred laws) and managed as a sustainable food source.

1. Culinary Value: They were often preserved in their own fat (huahua) and served to high-ranking guests.

2. Trade and Gifts: Kiore were frequently used as valuable items for exchange or as part of a bride's dowry.

3. Ownership: Different tribes maintained specific territories for trapping, and infringing on another’s "rat run" could lead to conflict.

IV. Ecological Consequences for New Zealand

The introduction of Kiore Pacific rats had a profound effect on New Zealand's isolated ecosystem. Before their arrival, many native species had evolved without mammalian predators.

• Bird Populations: Kiore preyed on the eggs and chicks of ground-nesting birds and smaller seabirds.

• Reptiles and Invertebrates: They contributed to the decline, and in some cases extinction, of various lizard species and large flightless insects like the wētā.

• Plant Life: By consuming large quantities of seeds, they altered the regeneration patterns of native forests.

V. Decline and Current Status

The dominance of the Kiore ended with the arrival of European settlers in the 19th century. The introduction of larger, more aggressive competitors—the Norway rat and the ship rat—alongside predators like stoats and cats, caused Kiore populations to plummet on the mainland.

Today, Kiore Pacific rats are primarily found on various offshore islands and in remote parts of Fiordland. They remain a subject of complex debate: while conservationists often seek their eradication to protect endangered native wildlife, many Māori iwi regard them as taonga (treasures) with significant ancestral and cultural value.

By Alina Basics.

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