Possums and predators in New Zealand: how many, the damage, and Predator Free 2050

About 30 million possums lived in New Zealand in 2008/09, according to the most recent national estimate, made by Landcare Research (now Manaaki Whenua) in 2009¹. Without any pest control, the study estimated 47.6 million, so control was holding numbers about 36% lower.

• Possum control in 2008/09 covered about 13.3 million hectares (33 million acres), around half of New Zealand's vegetated land¹.
• Most possums live in native forest: without control, about 28.5 million of the 47.6 million (60%) would be in native forest other than beech¹.
• The 2008/09 estimate is about 5.7 possums for every person living in New Zealand today (our calculation)⁸.
• Across the 26.8 million hectares the study mapped, it works out at about 113 possums per square kilometre (about 290 per square mile), by our calculation¹.
• The authors warn that, until better estimates of how many possums each type of land can carry are available, the total "will always be speculative"¹.

Southland had the most possums in 2008/09, about 5.1 million, followed by Bay of Plenty (4.1 million) and the West Coast (3.7 million), according to Landcare Research¹. The West Coast would have the most without control: about 8.3 million.

• Wellington had the biggest reduction from control, 87% below the number the land could carry¹.
• Hawke's Bay, Manawatū-Whanganui (Manawatu-Wanganui) and the West Coast also had reductions of more than 50%¹.
• Gisborne (1%) and Nelson (0%) had almost no reduction¹.

Yes. In Victoria, for example, possums "are protected under the Wildlife Act 1975", and it is illegal to harm or harass them, although common brushtail possums living in buildings, municipal parks and gardens may be controlled⁹. In New Zealand the same species, the common brushtail possum (Trichosurus vulpecula), is a pest that the Predator Free 2050 goal aims to eradicate².

No national count of stoats has been published. DOC says they live "anywhere from beaches to remote high country"; stoats, weasels and ferrets were introduced as early as 1879 to control rabbits¹¹.

• Stoats cause about half of kiwi chick deaths on the mainland, and without management only 10% of kiwi chicks survive to six months¹⁰.
• A stoat needs the food equivalent of 12.5 pīwakawaka (fantail) chicks a day, and a female can have up to 12 kits at a time³.
• Stoats can swim 1.5 km (0.9 miles) to reach islands, and young stoats have travelled more than 70 km (43 miles) in two weeks¹¹.
• DOC says stoats are implicated in the extinction of the South Island subspecies of bush wren, laughing owl and New Zealand thrush¹¹.

Predator Free 2050 is the New Zealand Government's goal, adopted in July 2016, that "by 2050 every single part of New Zealand will be completely free of rats, stoats and possums"⁴. On 21 November 2025 the Government announced that feral cats would be added to the target list, with detail due in the revised strategy in March 2026⁵.

• The Government started with NZ$28 million for a new company, Predator Free New Zealand Limited, on top of the NZ$60 million to NZ$80 million it already spent on pest control each year⁴.
• DOC now partners on 20 large predator-free projects covering 1,107,800 hectares (2.7 million acres), which it says is about 18 times the size of Lake Taupō (Taupo)¹³.
• New Zealand has eradicated predators from two-thirds of its offshore islands, and achieved the world's first island eradication in 1960¹³.
• More than 9,000 projects upload their trapping results to Trap.nz¹³.
• Close to 3,400 submissions were made on the Predator Free Strategy, and over 90% backed better feral cat management; pet cats are not part of the target⁵.

Fenced sanctuaries and pest-free islands are where the results are easiest to see, and DOC encourages people to visit them¹³. If you are touring with campervan hire in New Zealand, DOC's interactive map of predator control projects can help you find one near your route.

Aerial 1080 operations covered 1,052,056 hectares (2.6 million acres) in 2024, the largest area and the most operations (65) since the Environmental Protection Authority (EPA) began reporting⁷. The EPA links the rise to heavy beech seeding in 2023. The 2024 area was 2.8 times the 374,227 hectares treated in 2015¹⁴.

• 1080 (sodium fluoroacetate) is dropped from helicopters as bait pellets over large, remote and rugged areas where traps cannot be used; DOC says four to six pellets typically land in an area the size of a tennis court³.
• On average, DOC says, an operation removes 98–100% of rodents and 90–100% of possums and stoats, but numbers rebound, so operations have to be repeated³.
• Of the 2024 operations, 45 targeted possums, 44 rats and 29 mustelids; many targeted more than one pest⁷.
• The EPA received 29 incident notifications from 17 of the 65 operations in 2024, including nine reports of non-target animal deaths and nine cases of bait landing where it was not supposed to⁷.
• The EPA says the use of 1080 "can be controversial". In 2007 its predecessor, ERMA, reassessed 1080 and decided that, with tighter controls, its benefits outweighed the risks; since then operators have had to report on every aerial operation⁷.