At night, somewhere in the wet subalpine scrub of northwest Nelson or the Paparoa Range, a large bird is moving through the dark with its face pressed to the ground. It is not lost. It is hunting by smell, which is an unusual career choice for a bird, but the great spotted kiwi committed to this direction a very long time ago and shows no signs of reconsidering. Roroa is the largest of New Zealand's five kiwi species, a distinction that comes with a bill to match. That bill, long and ivory-pale, carries the nostrils at its tip rather than its base, which is the kind of anatomical decision that raises questions until you understand that it is actually a precision instrument for detecting earthworms through several centimetres of soil. The eyes are small and largely decorative. Eyesight is not the point here. On the ground, it moves with the purposeful, slightly aggrieved energy of something that has decided the whole arrangement is reasonable enough. By day it retreats into a burrow, sometimes shared with a long-term partner, because roroa are monogamous and territorial in ways that suggest a genuine investment in the arrangement. Pairs hold large territories and defend them with a call that carries a long way through mountain forest after dark: the male's rapid ascending whistle, the female's slower, lower trill. If you have walked the Heaphy Track at night and heard something in the scrub that sounded urgent, this was probably the source. The egg is the other thing worth remarking on. A female roroa produces a single egg that can reach up to a quarter of her own body weight, which is a physiological commitment so extreme it sounds like a rounding error. She then largely hands it to the male, who incubates it for up to 85 days. Both parents share duties in the later stages. The chick, when it finally arrives, is immediately independent in the sense that it must begin foraging for itself within days, but independent does not mean safe. In a mast year, when beech seeds flood the forest floor and rat populations surge, stoat numbers follow close behind. Most chicks do not survive their first year. The rugged, wet, high-altitude terrain roroa prefers offers some natural insulation against predator pressure, which is why the species has fared better than most kiwi. But better is relative. Around 14,000 remain across four genetically distinct populations, and the number edges down by roughly 1.6 per cent each year. At that rate, projections are not comfortable reading. Predator control, especially the suppression of stoats across large areas during mast years, is what keeps the trajectory from worsening faster. The roroa continues, for now, because people are doing a great deal of work to ensure that it can.