A little insight into the nesting habits of NZ's tiniest birds

Have you ever wondered just how small the eggs of our tiniest native bird are? Well I’m here to show you, and give you an insight into titipounamu / rifleman nesting season.

Firstly an important disclaimer: The monitoring of nests is a delicate operation, nesting birds are sensitive, defensive and vulnerable. It is important to never approach or disturb a nest or nesting bird, as you could force them to abandon their precious eggs or chicks. We monitor the titipounamu at Zealandia Ecosanctuary because they are a relatively new species to the area and it’s important to have a big picture of how they are adapting to the location. Without monitoring we wouldn’t have any idea of their population size or how well they are reproducing. All nest checks are carefully planned to minimise disturbance to the birds, we watch from a safe distance that we know will not cause stress to the birds and all actions and handling are conducted under permit.

I was extremely privileged this past season to be involved with helping to monitor the titipounamu nests scattered throughout Zealandia Ecosanctuary. Since I have spent the last few years getting to know titipounamu I felt confident that I could help with nest checks without causing them stress. Titipounamu are extremely grumpy little birds, they are very defensive of their nests and can get upset very easily. Knowing the birds so well meant that I could immediately tell if they were aware of me, and if I was upsetting them I could quickly move away and let them get on with their day. As the birds have different personalities I learned that some were quite ok with me being in their territory, whereas others would start alarm calling before I was anywhere near their nest!

Titipounamu are cavity nesters, which means they build nests in existing spaces, like a hollow space in a tree. The nests are seriously impressive, inside the hollow space they build their spherical nest which is expertly constructed from leaf skeletons and small twigs. The structure has a little foyer then a wall with a tiny entrance hole just big enough for them to squeeze through, this leads to the bowl which is lined with lots of soft feathers to keep the eggs and chicks warm. It’s so mind-blowing that such tiny light weight birds can build such an elaborate construction.

Front view showing constructed entrance.

A feathered bowl.

Fortunately titipounamu will happily use artificial nest boxes if they are provided, which makes it much easier to monitor the population. The nest boxes are strategically placed throughout the sanctuary to target specific pairs and offer them a cosy space to nest in. Titipounamu are loyal birds, both to their mate but also their territory, once they settle into a territory they will remain there for many years. Some birds at Zealandia have been nesting in the same spot (give or take a few metres) since 2019!

A tiny bird lays tiny eggs right? Well kind of, although titipounamu eggs are extremely tiny, they are quite large when compared to the females body size. Female titipounamu are 9cm long and weigh 7 grams, their eggs measure 1.6x1.2cm and weigh 1.5 grams, so each egg that she lays is a quarter of her weight! Once she’s done laying eggs (2-5 is a typical clutch) the birds begin incubation. They take turns, but duties aren’t divided equally. Male titipounamu will spend longer in the nest, this is thought to give the females more time to forage for food to gain back strength and condition after egg laying, and also she’s bigger so she needs slightly more food.

Infertile titipounamu eggs. Only removed once there was absolutely no chance the eggs were viable. (Weeks after they would have hatched).

The entire nesting process for titipounamu is shared between both parents, right up until the chicks hatch, then fledge. After the first clutch fledges the female gets started on a second nest straight away, sometimes there’s even an overlap, one female this past season had already laid an egg in her second nest while she was still feeding chicks in the first!

I hope you’ve enjoyed this little insight into the world of our tiniest birds. They are truly remarkable little creatures with big personalities and complex lives. Tiny quiet birds can often get overlooked in a forest full of louder, bigger ones so I hope to keep bringing attention to these tiny tree potatoes as I really believe they are one of our most special native birds.

Newly fledged titipounamu chicks huddling together.