A museum specimen suggests it did, but is this specimen reliable?
Nowadays, you can only find the New Zealand Rockwren (Xenicus gilviventris) on the South Island of New Zealand. This small songbird, in Māori known as pīwauwau (“little complaining bird”), is currently threatened with extinction, partly due to predation by introduced predators. To conserve this iconic bird, biologists are searching for predator-free areas to reintroduce it. One possibility is the other main island of New Zealand: North Island. However, conservationists prefer to reintroduce species into their former ranges, which raises the question: Did the New Zealand Rockwren ever occur on North Island?
One way to figure out whether the New Zealand Rockwren ever hopped around North Island is to dive into museum collections. Alexander Verry and his colleagues found a specimen (labelled NHMUK 19188.8.131.52) that was collected by Henry H. Travers in the Rimutaka Ranges on North Island. Mystery solved!
No so quick (otherwise, this would be a very short blog post). Perhaps the specimen was mislabeled or it might represent a different species. To rule out these possibilities, the researchers extracted DNA from the museum specimen and compared it to modern samples with known origins.
Previous genetic work revealed that the New Zealand Rockwren consists of two main groups: a northern and a southern lineage on South Island. The specimen collected by Travers clustered with samples from the southern lineage, a long way from the Rimutaka Ranges on North Island. It thus seems that the specimen was mislabeled.
Mistakes happen. However, mistakes appear to have happened quite regularly to Henry Travers. Three other specimens that he might have collected came from the Otago Province (according to the labels). The genetic data, however, suggest that these three samples originated from the northern part of South Island, some distance from the Otago Province. Moreover, Henry Travers was involved in other mislabeled specimens, such as skins from the South Island Snipe (Coenocorypha iredalei). It is reasonable to doubt the collection and labeling skills of Henry Travers.
The authors conclude that: “Our results suggest that New Zealand rock wrens have not been historically extirpated from New Zealand’s North Island, and that caution must be taken when utilizing museum specimens to inform conservation management decisions.”
Verry, A. J., Scarsbrook, L., Scofield, R. P., Tennyson, A. J., Weston, K. A., Robertson, B. C., & Rawlence, N. J. (2019). Who, Where, What, Wren? Using Ancient DNA to Examine the Veracity of Museum Specimen Data: A Case Study of the New Zealand Rock Wren (Xenicus gilviventris). Frontiers in Ecology and Evolution, 7, 496.