Introducing Imber’s petrel: a new recently extinct seabird species for New Zealand

New Zealand has a new species of seabird. Te Papa scientists recently described Imber’s petrel (Pterodroma imberi) from the Chatham Islands as a new species.

A previous study that measured a large number of seabird bones from the Chatham Islands found three size categories.

Frequency graph of the lengths of humeri (wing bones) of all Pterodroma bones on the Chatham Islands. The largest and smallest bone classes correspond to known species. The middle-sized bones belong to a new species. Graph from Copper and Tennyson (2008) [http://www.dinosauria.org/docs/oryctos/07_19_cooper.pdf]

Frequency graph of the lengths of humeri (wing bones) of all Pterodroma bones on the Chatham Islands. The largest and smallest bone classes correspond to known species. The middle-sized bones belong to a new species. Graph from Copper and Tennyson (2008).

The largest bones belong to the Magenta petrel/taiko (Pterodroma magentae) and the smallest bones matched Chatham petrel (Pterodroma axillaris) bones. Both these species still occur on the Chatham Islands but both are endangered.

The middle-sized bones didn’t match any living petrel species in the Chatham Islands and were suggested to represent a new species. In our new study we tested this idea by comparing DNA sequences from these bones to sequences from other petrel species.

Holotype of Imber’s petrel. Sampling bones for DNA typically involves drilling holes or cutting chunks out of them. However, for this bone we were able to soak DNA out of the bone without damaging it.

Holotype of Imber’s petrel. Sampling bones for DNA typically involves drilling holes or cutting chunks out of them. However, for this bone we were able to soak DNA out of the bone without damaging it.

The DNA confirmed that the sampled bones were indeed from a new species. It was more closely related to species from the New Zealand mainland than to the other Chatham Island petrel species. We named this petrel Imber’s petrel (Pterodroma imberi) after Mike Imber (1940-2011), a New Zealand ornithologist who studied petrels and undertook extensive fieldwork in the Chatham Islands.

Like many New Zealand bird species, Imber’s petrel became extinct following human settlement – it was likely hunted and eaten by introduced animals. Our description of Imber’s petrel brings the number of New Zealand bird species extinct since human arrival to 54.

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