Southern New Zealand dotterel

Together, the southern New Zealand dotterel, and its cousin, the northern New Zealand dotterel, were lumped into one species under the name New Zealand dotterel. However, studies have shown that there are significant morphological differences to justify the separation of these two subspecies, with the southern subspecies being far more bulkier. Not only that, but different environments on the South Island may have given rise to different features, such as stronger winds necessitating a longer middle toe and claw. There are also significant differences in behavior, with the northern New Zealand dotterel preferring sandy beaches, while the southern New Zealand dotterel prefers inland nest sites, wintering on the South Island's beaches.[2] In 2014, this subspecies was split by some taxonomic authorities.[3]

While it was formerly found throughout the South Island, it is currently restricted to Stewart Island, where it breeds on inland mountain tops, plains, and river valleys.[1][2]

It has been subject to numerous fluctuations. While it was extirpated from the South Island primarily due to introduced species, such as feral cats and stoats, it experienced a brief swell in population size to around 290 birds in 2005, followed by a period of intense decline for unclear reasons, dropping to around 120 individuals. While the cause is unknown, it has been concluded it is not due to a lack of recruitment, but rather some decline of mature birds, as suggested by the sheer drop in population. Consequently, it has been categorized as critically endangered.