Brown teal survival rate put down to control

More brown teal/pāteke in Fiordland National Park have survived this year than ever before and rangers involved are celebrating the success of predator control.

The small brown ducks are found only in New Zealand, previously becoming extinct in the South Island due to the combined impacts of predators, habitat loss and other threats.

Since 2009, brown teal reared in captivity have been reintroduced to the area around the Milford Track — one of only two restored populations in the South Island.

Doc biodiversity ranger Louise McLaughlin and team celebrated the success by releasing 40 more captive-reared brown teal in the Arthur Valley to join their thriving friends earlier this month.

She said with support from Air New Zealand and iwi, Doc staff had been releasing and monitoring the birds with specialised transmitters.

"We’re not just throwing them out there and hoping for the best. We’re tracking their survival, and learning, always learning.

"With high rainfall and risk of floods, this can be a tough location for pāteke, but their biggest threat remains their vulnerability to introduced predators. They just don’t have a ‘fight back’ mechanism at all — they’re sitting ducks.

"Fortunately, we’ve seen incredible survival rates following 1080 predator control operations. This year we’ve had more than 86% survival. In the years when we don’t have 1080 operations, survival can drop to as low as 16%."

With more birds in the rivers, visitors to the Milford Track are more likely to spot this unique duck in the future.

Every year 25 million native birds are killed by invasive predators. Doc’s national predator control programme protects threatened native species by regularly suppressing introduced predators across large forest areas on conservation land.

In the Arthur and Clinton Valleys, Doc uses aerially applied biodegradable 1080 to target rats, possums and stoats, supported by traps along the valley floor to target stoats in between 1080 operation years. The frequency of 1080 operations is dependent on predator numbers, and the most recent operation was in 2024.

"It’s so wonderful doing the monitoring after we’ve had a 1080 operation. There is more life in the forest, there are more nests, more fledglings, and it’s not just pāteke — it’s benefiting all our native forest animals," she said.

With predators controlled, brown teal have a chance to build their resilience to natural threats.

"We’re finding that the longer they survive out there, the better they get at putting their nests in smart locations above the floodline. The population is becoming more savvy, more fit for this location." — APL