Tītipounamu thriving in the sanctuary
I hear the calls, a high-pitched buzzing ‘zipt, zipt, zipt’. Scanning high in the canopy, I spot a couple darting to and fro with their quick movements. These are the elusive tītipounamu/ rifleman, which I’m excited to spot at last since their introduction in March this year, with the help of ranger Kari Beaven.
We head up a steep slope on the western scarp of the lower lake, and crouch low to observe a nest. Kari says this is the pair’s second nest for the season – and sure enough, I spot the female coming to feed her chicks several times. A quick food drop, then she’s away out again.
“This pair fledged four chicks in October and the fledglings were hanging out in the valley like a neighbourhood gang. They made it hard for me to tell if another nearby nest had fledged, or if it was just the neighbour’s mum chasing the rowdy group away from her own nestlings!
“What I want to know is, is the new population growing enough to establish a strong foundation? That’s why I’m trying to find the nests, and to count how many fledglings there are from each pair. This pair raised four fledglings. That’s a great number and I would have been very happy with that but now they’re nesting again, so I’m thrilled.”
There’s something wonderful about sitting quietly in a sheltered spot – the morning band of rain has just cleared, the leaves glistening, the soil pungent – watching these tiny birds go about their business, making themselves at home in the sanctuary.
Kari explains why she’s keen to see many chicks this season: “The best scenario would be for the new population to increase really quickly. These founding birds carry the whole suite of genes, particularly the rare alleles [variant form of a given gene] that are going to exist in ZEALANDIA. Genes are passed down randomly, so the more chicks each of the founding pairs have at this early stage, the greater the variety of genes passed on to the establishing population. The wider the variety, the more adaptable these birds will be; as the climate changes and new diseases, parasties and other challenges are introduced, we need resilience.”
So far so good; 14 nests have been located in the sanctuary (and one just outside), mostly in natural cavities and a few provided nest boxes.
“Zealandia is a great place for tītipounamu. At the moment these founders have got it made. As the first ones to return here, there is a lot of space and new food available for them in their given niche, without competition from other titipounamu. They can put the energy they save into nesting. I also think the ready availability of fresh water year-round makes a big difference. Even in the driest months, water can be found right throughout the valley.”
Descending the hill, Kari gets a radio call from another ranger. A fledgling, identified individually by its leg bands (blue/blue) has been spotted with a group of unbanded fledglings on the Round-the-lake track, in the upper part of the valley.
Kari explains what this sighting could mean: “Parents will feed fledglings for as long as they can, to give them a good start in life. The main reason they stop is to focus their energy on a new nest. If the parents aren’t feeding blue/blue, it would be good timing to have a look at what they are up to instead.”
Kari says they’re noticing groups of fledglings from different nests hanging out together. It could be that this gives them the opportunity to find a pair ahead of next season. There is so much we don’t know about their behaviour.
We head up the Te Mahanga track and spot several more fledglings; then up to the Swamp track to check out what might be happening with a pair who’ve already produced chicks. Are they re-nesting?
Kari explains tītipounamu have very high metabolisms and need to feed constantly, so the male and female will share incubation of the eggs for 10-20 minutes at a time. Therefore, if you see pair together for long enough, it’s likely they’re not nesting. If you can follow one of the pair but cannot find the other, it may be they are on a nest.
“This is my favourite thing to do, observe birds and try to work out what’s going on.”
Kari observes the behaviours closely of those at the Swamp track and concludes they’re not re-nesting yet, but from what has been reported to her by volunteers who have been spending time in the area, they will be close.
“This is one of the strengths of ZEALANDIA. With a vibrant group of volunteers, researchers and staff in the valley, there is so much potential to notice and learn from what is seen. An amazing local photographer sends me updates on their behaviour and photographs of what she has seen that is of interest or difficult to interpret, and we are both learning! What we learn here can be used to predict what will happen for species released into other areas around the country where close monitoring may not be an option, for example because of remoteness or the size of an area.
Heading back out for the day Kari sums up: “I’m really pleased with how the population is going, the numbers are increasing rapidly. We’ve found at least half of the birds we translocated and there are likely to be more birds than what we know about. There are so many hidden nooks and crannies throughout the valley that would be perfect for them, and a number of places where they have been heard once or even a few times, but where no one has been able to confirm a pair or their bands.
Last month one of the wonderful rangers here found a whole new family that we hadn’t seen before, while out doing their hihi work. They were nestled in a beautiful patch of forest between two other pairs. We had suspected there might be a pair in there but she came back having found a ready made family group, with mum, dad and four fledglings!”
“I’m comfortable this new population is doing well. They’re making a very good start and at this stage we don’t need to do anything more. It’s really cool – there are now tītipounamu living in Wellington!”
Written by Margaret McLachlan
Photo by Melissa Boardman