The North Island giant moa became extinct primarily because of overexploitation by humans after Polynesian settlement of New Zealand. Hunting of adults and collection of eggs reduced its population faster than it could reproduce, while human-caused habitat loss added further pressure.
This is an anthropogenic extinction: an extinction caused directly or indirectly by human activity. It is relevant to A4.2 Conservation of biodiversity at both SL and HL.
| Factor | How it contributed to extinction |
|---|---|
| Hunting | Moa were large, flightless birds and therefore relatively easy to locate and kill. Archaeological sites containing butchered moa bones provide direct evidence of hunting. |
| Egg collection | Humans consumed moa eggs, reducing recruitment because fewer young birds entered the breeding population. |
| Slow reproduction | Moa were long-lived birds with low reproductive rates. Their populations could not replace adults and eggs removed at an unsustainable rate. |
| Habitat destruction | Human use of fire converted areas of forest and shrubland into open vegetation, reducing feeding and breeding habitat. |
The timing strongly supports human causation. Polynesian settlers arrived in New Zealand in the late thirteenth century, and moa disappeared within approximately one to two centuries. Genetic evidence indicates that moa populations were viable before human arrival, contradicting the idea that they were already undergoing a long-term natural decline.
The key mechanism was therefore: human arrival → intense hunting and egg collection → mortality exceeding reproduction → decreasing population size → fewer breeding individuals → extinction. Habitat alteration accelerated this decline but is generally regarded as a contributing factor rather than the main cause.
A common misconception is that climate change alone caused the extinction. Evidence instead links the rapid decline closely to human settlement and exploitation.
Exam technique: For an A4.2 question asking you to explain this extinction, identify hunting as the principal cause, link slow reproduction to failure of population recovery, and support the explanation with archaeological, chronological or genetic evidence. Do not simply list “human activity”; explain the biological mechanism by which it caused extinction.
