Photo/Illutration From left, female and male Torishima-type short-tailed albatrosses and the slightly smaller female and male Senkaku-type albatrosses (Miwa Konno, a member of the research group)

The endangered short-tailed albatross, a designated Japanese special natural treasure that lives on remote Japanese islands, is actually two different species and should be classified as such, researchers said.

The seabirds that have bred on Torishima island in Tokyo’s Izu island chain and the ones born on the Senkaku Islands in Okinawa Prefecture have physical differences largely stemming from genetic factors, according to the research group comprising members from the Hokkaido University Museum and the Yamashina Institute for Ornithology.

The Torishima-type albatross has a slightly larger body, while the Senkaku-type has a longer bill, their study showed.

Their findings appeared in a scientific paper published in a biology journal on Nov. 19.

The short-tailed albatross was considered extinct in 1949, but the large seabird was rediscovered in 1951. Its population has now bounced back to about 6,000.

Leg rings are attached to individuals born on Torishima for identification. But ones without leg rings have also been found on Torishima, indicating that they were born on the Senkaku Islands and traveled to the island south of Tokyo.

A previous study conducted by Masaki Eda, an associate professor at Hokkaido University, and other researchers showed that the genetic difference between the Torishima- and Senkaku-types is broader than between the wandering and Amsterdam albatrosses, which are considered separate species.

The research also showed that the two albatrosses in Japan tend to choose their own types for mating.

For the latest study, the scientists captured 24 short-tailed albatrosses on Torishima for comparison. It became clear that they have different physical attributes, including the length of their bills, and should be classified as separate species, they said.

They suggested maintaining the “Ahoudori” (short-tailed albatross) name for the Torishima-type and calling the Senkaku-type as “Senkaku Ahoudori” in Japan.

“When we consider them as separate species, Senkaku Ahoudori is clearly small in number. We need to be aware of their difficult situation,” said Naoki Tomita, a researcher at the Yamashina Institute for Ornithology.

Currently, both Ahoudori and Senkaku Ahoudori live on Torishima island.

“We must protect their own distinctive features while moving ahead with a better conservation plan,” Eda said.

To read the paper, go to (https://www.int-res.com/abstracts/esr/v43/p375-386/).

Related News