Behind the scenes at the Auckland War Memorial Museum, a "menagerie" of specimens is a treasure trove for curator Dr Matt Rayner, who is researching how the Hauraki Gulf's seabirds are faring using clues from very old feathers.

"A menagerie" is how curator Dr Matt Rayner describes the land vertebrate collection in the backrooms of the Auckland War Memorial Museum.

There's a horse's head, stuffed peacocks sitting on a workbench, and the back corridor is filled with large specimens - moa, emu, and ostrich as well as reindeer, caribou and rhinoceros heads and skeletons.

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We're most familiar with museum galleries: carefully curated spaces, designed to tell stories. Precise taxidermy allows animals to stand or perch as they would in real life.

But in most museums, these front-facing displays are only a tiny percentage of the collections they house. Behind the scenes, there's a lot more going on.

As a curator, Matt works on public displays - but he also has his own area of research: seabirds.

For a recent project, Matt wanted to know: what's happening to the seabird residents of Tīkapa Moana the Hauraki Gulf across time? It's a tricky question to answer given that seabirds haven't been particularly well studied over a long period of time.

"Many of our land birds have been counted for decades, whereas we're just catching up with seabirds," he says. So, in the absence of long-term data, Matt and his colleagues turned to the backroom specimens held at museums for clues.

Matt scoured the collections at Auckland Museum, Te Papa Tongarewa, and Canterbury Museum for five seabird species found in the Hauraki Gulf: kāruhiruhi / pied shag, pārekareka / spotted shag, kororā / little penguin, tara / white-fronted tern, and tarāpunga / red-billed gull.

He focused on specimens collected from the Gulf over the years, all the way back to the 1880s. Then, he sourced feathers from his chosen specimens.

Matt also collected feathers from contemporary live birds during fieldwork in the Gulf, assembling a timeline of seabird feathers stretching from the 1880s to now.

Matt analysed certain elements in the chemical makeup of the feathers using stable isotope analysis. Looking at the stable carbon and nitrogen isotope signatures from these feathers can give Matt general insights into what the birds were eating and where they were living when the feathers were grown.

The nitrogen isotope analysis didn't indicate much change in the types of food these birds were eating (such as fish or crustaceans and squid)…

Go to this episode on rnz.co.nz for more details