Rifleman Series: Part 4 - Egg Sitting

The tītipounamu is an elusive bird. Their high-pitched calls often go unheard by many. They are also the smallest bird of New Zealand, with the riroriro (grey warbler) coming close in second with the same weight and only a longer tail. They are hard to find and hard to keep track of, especially during this time of year.

It’s mid-October and it’s almost time to incubate the eggs. The female lays one last egg and begins sitting on her eggs. The male sits on the eggs 1.5 times longer than her each time. If she had been in there for 15 minutes, he would be there for 20. Is this because she is bigger, and she needs more food? During incubation, the feathers on both the parents’ abdomen start to fall off, developing a brood patch to transfer their body heat straight from their bare skin, making it the most effective to grow their babies inside the eggs. The male occasionally brings a fresh piece of down feather to keep the lining of the nest warm and cozy. They also cover the entrance of the hole with feathers while incubating, like a curtain, to create near-perfect insulation! Here's an example:

This is also when they are hardest to track, because they don’t forage in pairs anymore and have no need to produce contact calls. And they need to keep the location of their nests unsearchable by predators. Before we know it, the forest is suddenly silenced of tītipounamu… Weeks would go by without us finding a new nest. This month was the hardest for us, as we gradually realize that they are trying to keep silent and not allow anyone to follow them to their nests. Imagine fresh juicy eggs, warm to touch, which predator can resist that? Not finding new nests every other day crushed our spirits a little and reduced our productivity in the field. Alas, we pushed on, monitoring closely the behavior of pairs at known nests, and working on a good system for data backup. Many say that perseverance is the key to a successful PhD journey. And this is where we shall apply this valuable advice. The beautiful sunrise everyday seen from the research station definitely helps.

In the next blog post in this series which will be published on the 11th February 2019, I will talk about babies. Who doesn’t like babies? Hang tight!