South Island Robin

Overview

The South Island robin (Petroica australis), also known in Māori as the kakaruai, is a sparrow-sized passerine endemic to New Zealand and protected as an endemic species. Although classified as Least Concern by the IUCN, the species faces challenges from habitat loss and introduced predators, particularly in the Stewart Island subspecies.

Identification

• A small passerine measuring 10–18 cm in length and weighing approximately 35 g.
• Males are dark grey with a distinct yellowish-white lower chest, while females and juveniles are lighter grey with less distinct breast markings.
• The species resembles the North Island robin and Stewart Island robin, particularly in female and juvenile plumage.
• Males produce a loud, clear, and continuous song that can last for more than 30 minutes with very brief pauses, typically sung from the canopy or emergent trees during the breeding season.

Habitat

Found sparsely and discontinuously across the South Island and Stewart Island / Rakiura, the species has a strong affinity for Douglas fir plantations due to their structurally simple forests with dense canopies and leaf litter. Historically present throughout lowland New Zealand, its distribution has become patchy due to habitat reduction, though populations have been successfully translocated to predator-free islands such as Ulva Island and Motuara Island.

Diet

The diet consists primarily of invertebrates, including earthworms, beetles, and arthropods foraged from leaf litter, with occasional consumption of uncached berries. The birds demonstrate exceptional numerical competency, prioritising and differentiating up to 12 cached items, and spend up to 90% of their day foraging in winter due to high metabolic rates.

Did you know?

South Island robins have demonstrated the highest recorded numerical competency of any wild animal, capable of differentiating and prioritising caches of varying sizes up to 12 total items without training.