Feral Cats: A Continuing Threat to Nēnē
Discover the historical origins of feral cats in Hawaii and their ongoing impact on the nēnē, Hawaii's native goose, amidst regulatory challenges.
History and Escalation of the Feral Cat Threat
Introduced to the Hawaiian Islands by European sailors in the late 18th century, feral cats (Felis catus) have evolved from a maritime utility to one of the most significant threats to the nēnē (Branta sandvicensis), Hawaii's endemic goose. Their arrival, likely during Captain James Cook's expeditions in 1778-1779, aimed to control rodents on ships, but their subsequent escape or abandonment led to widespread feral populations by the early 19th century, as first documented by missionary William Ellis in 1823 [Hawaii State Archives].
Today, with an estimated nēnē population of 3,797 as of 2023 [NRAG, 2023], feral cats continue to jeopardize this species through predation, habitat displacement, and disease transmission. These threats persist despite a remarkable recovery from fewer than 30 birds in the 1950s, highlighting the urgent need for effective feral cat management amidst Hawaii's inconsistent legal framework [U.S. Fish & Wildlife Service, 2022].
Current Threats to Nēnē
Predation
Feral cats are documented predators of nēnē, with particular impact on eggs, goslings, and nesting adults. Camera trap studies have recorded predation events across major nēnē habitats, with significant impacts documented on Kauaʻi, Maui, and Hawaiʻi Island [DLNR-DOFAW, 2023].
Habitat Displacement
Feral cat colonies near nēnē habitats create zones of elevated predation risk, particularly affecting breeding populations. This threat is most pronounced on Kauaʻi, where 2,314 nēnē reside [NRAG, 2023]. Research indicates that nēnē alter their habitat use patterns in response to feral cat presence, often avoiding otherwise suitable nesting areas [Banko et al., 2020].
Disease Transmission: Toxoplasmosis
Feral cats are the definitive hosts of Toxoplasma gondii, a protozoan parasite causing toxoplasmosis. This disease has been documented as a significant mortality factor in nēnē and other native Hawaiian species [Work et al., 2016]. Studies have shown that a single infected cat can shed millions of environmentally resistant oocysts that remain viable in soil and water for extended periods, creating long-term infection risks [Shapiro et al., 2019].
Interactive Island Laws
Click an island to view applicable state and county laws for pets and feral cats:
Mitigation Strategies
Current scientific evidence supports the following management strategies to protect nēnē from feral cat impacts:
- Monitor feral cat populations by reporting sightings using our CatMap tool , supporting data-driven management efforts.
- Comply with Hawaii Revised Statutes §143-2.6, which requires pet cats to be microchipped and maintained indoors or in enclosed outdoor areas [HRS §143-2.6].
- Support spay/neuter programs and contribute data through CatMap to help protect nēnē populations.
- Avoid feeding feral cats, a practice often prohibited near endangered species habitats under HRS 195D-4, to prevent attracting nēnē to unsafe areas.
Further Insights
Feral Cat Threat Profile
Historical Introduction
Arrived with European ships in late 18th century.
Impact Range
Present across all main Hawaiian islands where nēnē (pop. 3,797) reside.
Primary Threats
Direct predation, disease transmission (toxoplasmosis), and habitat disruption.
Key Actions
- Report feral cat sightings using our CatMap tool .
- Keep pet cats indoors to prevent them from becoming threats to native wildlife.
- Follow the DLNR Feral Cat Management Guidelines .
- Do not feed feral cats, especially near nēnē habitats.
- Learn more about invasive species impacts at HISC .
Legal Overview
Abandoning cats is illegal. Feeding near nēnē risks fines or jail. State feral cat management is inadequate.