True love takes a ‘tern’ in the Mackenzie basin

Source: NZ Department of Conservation

Date:  19 November 2025

Trail cam photos have revealed the special story of a black-fronted tern/tarapirohe pair battling severe unseasonal weather to bring their chicks into the world.

Department of Conservation staff in Twizel downloaded photos from trail cameras focused on the colony nesting on an island in the middle of the Upper Ōhau River.

They looked at the photos in trepidation as a week before there was an unseasonal heavy snow fall. Staff were worried the tarapirohe had abandoned their nests, as many had done during a similar weather event at the same time last year.

Ranger Emily Hewison said when she saw the photos of one pair of adult terns in the snow, she knew she was seeing something very special.

“A parent tern was sitting on the nest and within a couple of hours was completely buried. It didn’t abandon the nest which is what many birds would do. The pictures show her mate peering at her through a small hole in the snow over a period of 24 hours, until the snow melts.

“You then see them have a wee cuddle on the nest, before photos show two eggs. Then amazingly three days later we see both chicks hatched. I was just so thrilled. I’m in awe of these birds, they really fight for survival,” Emily says.

Last year a snowfall came at the same time, during Labour Weekend, and wiped out the nests. Rangers were worried they would have no fledglings for the season.

The nationally endangered birds have a unique colony in the Upper Ōhau river system where around 700 nest each season. This colony is the largest in the country.

DOC Biodiversity Ranger Sam Turner says trying to protect the terns is an emotional roller coaster.

“Last season was a bit of a disaster. Many of the birds abandoned their nests and then the black-billed gulls, another threatened species, moved in and preyed on some of the eggs. The impact from the snow was devastating. We did get some fledglings fly off for the winter, but it was a stressful season.

“This year we can see around 260 active nests so that’s super exciting. The terns are such good parents; they share the incubation and mate for life. What’s so amazing about these two on the trail cam photos, is the lengths they went to protect their nest. Their lives were at risk all the time.

“These little birds are so vulnerable but also quite feisty. If people are out naturing near the riverbeds, you will see them defending their nests dive bombing and fighting off anything that comes near their nests. They are battling for survival.”

Sam wants the public to know how special the tarapirohe are and what they’re up against.

“They’re only found in our braided rivers in New Zealand that’s the reason we work so hard as rangers, because if we lose them, they’re gone for good. Looking at these photos, hopefully people will appreciate how amazing these little birds are. This season looks a lot more promising for chicks than last year, so that’s fantastic news.”

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MIL OSI