New Zealand's first bird flu case was a native harrier, not the skua

A native swamp harrier brought to an animal hospital with a head injury turned out to be New Zealand's first confirmed case of H5 bird flu—a discovery that came almost by accident, and a week before officials thought the virus had arrived in the country.

The kāhu was found in Carterton, in the Wairarapa region, on July 9 and admitted to Massey University's Wildbase clinic. Staff suspected head trauma from being stuck in a fence. Brett Gartrell, a wildlife veterinarian and professor at the university, said the bird deteriorated overnight and was euthanized the following morning. As part of routine disease surveillance, it was tested for avian influenza. "We weren't even thinking about highly pathogenic avian influenza at the time," Gartrell recalled. "It was a surprise to all of us when it came back positive."

The timing matters. A brown skua found on Petone Beach in Wellington tested positive for the virus the day after the harrier was admitted—July 10. For weeks, that skua was believed to be New Zealand's first case. The harrier's infection, confirmed through testing completed by July 17, actually predates it by a day. The Ministry for Primary Industries' chief veterinary officer, Mary van Andel, confirmed the harrier's samples arrived at the laboratory on July 14 and underwent two rounds of testing: first to identify avian influenza generally, then to determine whether the strain was highly pathogenic or low-risk.

How the harrier caught the virus offers a window into how the disease moves through wild bird populations. Gartrell believes the bird scavenged on a sick seabird that had washed ashore during July's rough weather. This pattern—birds of prey becoming infected after feeding on diseased waterfowl—has played out repeatedly overseas. Peregrine falcons in the United Kingdom have been hit particularly hard by the virus for exactly this reason. "They pick up sick and dying birds and eat them and get infected themselves," Gartrell explained. "So, it does look like birds of prey are going to be really hit by this."

That prospect carries particular weight in New Zealand because of the kārearea, the country's only native falcon species. The Department of Conservation estimates the population at between 5,000 and 8,000 birds—already endangered, already fragile. If the virus spreads through that population the way it has through raptors elsewhere, the consequences could be severe. Gartrell identified the kārearea as "the biggest cause for concern" given those numbers.

As of late July, New Zealand had only two confirmed cases of bird flu in wild birds. The lull, however, is unlikely to last. Gartrell warned that infections often establish slowly at first, then accelerate as more birds become infected and transmit the virus to others. "We've been given a bit of a lull," he said, "but I think it still is definitely coming." Bird-to-bird transmission hasn't been documented in New Zealand yet, but across the Tasman, Australia was already seeing clusters of mortality in terns—coastal birds that flock closely together. As of mid-July, Australia had recorded 27 confirmed cases in wild seabirds, with South Australian authorities warning that local spread was "very likely."

The discovery of the harrier's infection underscores how the virus can arrive unannounced, infecting animals that weren't on anyone's radar. A bird stuck in a fence, brought in for trauma care, became the nation's sentinel case—a warning that the disease was already here, already moving through the food chain, already reshaping what comes next.