The population of New Zealand's critically endangered southern dotterel, known locally as pukunui, has risen by 52 percent in one year. The increase followed an intensive effort to control feral cats on Stewart Island, also known as Rakiura.
According to a media release published on April 21 by New Zealand's Department of Conservation (DOC), an annual count of the birds at beaches across Murihiku and Southland found that their population had grown from 105 in April 2025 to an estimated 160. This is the largest yearly population increase recorded for the shorebird since focused conservation work began more than 32 years ago. The growth followed a joint winter campaign in 2025 by the Department of Conservation and non-profit group Zero Invasive Predators.
The campaign targeted feral cats, which had brought the shorebird close to extinction by hunting adult birds and chicks in their mountain breeding areas.
Targeted predator control yields immediate breeding gains
Before the 2025 operation, the pukunui population had fallen sharply, dropping from 176 birds in 2020 to just 105 in early 2025. Feral cats were identified as the main cause of the decline. Wildlife managers estimated that cats killed up to 50 adult birds each year.
The 2025 aerial control campaign used biodegradable 1080 bait to target feral cats across important nesting areas on the mountain tops of Rakiura. In the Department of Conservation's official statement, DOC Rakiura Operations Manager Jennifer Ross described the immediate benefits of reducing the number of predators during the nesting season.
"After years of small gains, and more commonly, devastating losses, this is the result we needed to help save pukunui from extinction," Ross said.
"We managed to reduce feral cats to very low levels in the operational area. This protected adult birds while they nested and raised their chicks on the mountain tops." Ross explained that adult males are especially at risk from feral cats because they sit on eggs overnight, when cats are actively hunting. Protecting nesting areas allowed more pairs to form and raise chicks successfully. Some pairs hatched three chicks during the season.
The latest count found 91 surviving adult birds out of 97 adults previously known to be alive. It also recorded 56 newly banded young birds, one newly discovered adult and five birds without bands. Standard population estimates add five percent to account for birds that may have been missed during beach counts.
Long term threats remain on Stewart Island
Despite this record increase, wildlife officials warn that the southern dotterel remains at risk while feral cats continue to live on the island.
Trail cameras placed around the edges of the areas covered by the campaign have recorded feral cats near the boundaries of the cleared zones. Cats have also been found in other breeding areas across Rakiura. Dean Whaanga, a representative of the Ngāi Tahu leadership group involved in the Predator Free Rakiura initiative, said in the Department of Conservation's release that continued efforts are important for the island's wider environment.
"It's critical we continue to take action, not just for pukunui, but to uplift the mauri of Rakiura and enable other taonga species like kākāpō and tīeke to safely return," Whaanga said. Feral cats breed in the wild across Rakiura and live independently of human settlements. This means permanently removing them will require continued management across the entire island.
Ground trapping expansion to protect gains
Although no aerial predator control operation is planned for Rakiura in 2026, conservation teams are expanding ground traps and bait stations.
These efforts aim to stop feral cats from returning to the cleared nesting areas. The ongoing trapping work receives support from private donations through the New Zealand Nature Fund and tourism company RealNZ. Field teams are closely tracking the movement of feral cats across the island.
They want to find out how quickly the cats try to return to the high-altitude breeding areas. Genetic blood samples collected from newly banded young birds will also help researchers identify their parents and track the balance between males and females in the recovering population. The Department of Conservation's wider Pukunui Recovery Project aims to increase the southern dotterel population to at least 300 birds by 2035.