While there is an older report from Ishizawa Heigo (see 1. Sovereignty: Legal and Historical Aspects), Kuroiwa and Miyajima's 1900 report was the first proper survey of lifeforms in the Senkaku Islands. The pair were invited by Koga Tatsushiro, who was alarmed by a decline in seafowl, to survey all of the Senkaku Islands other than Taisho Island, which was written up in Chigaku Zasshi (Journal of Geography). A summary is below.
(1) The Kuroiwa Hisashi report (1900)
First of all, Kuroiwa is surprised by the multitude of birdlife around Uotsuri Island. He describes how the multitude of birdlife was not in a diversity of species, but rather a great number of birds. During the cold months two species, the short-tailed albatross and black-footed albatross, would flock, and many tens of thousands would descend upon Uotsuri Island. In the warm months they would mostly vanish, and the sooty tern and brown noddy would flock upon Kitakojima Island and Minamikojima Island in the hundreds of thousands, he says. (Ref. 1)
Kuroiwa also describes mosquitoes and bluebottle flies as plentiful on Uotsuri Island. The swarms were so thick that it was impossible even to eat safely, and he urges caution among visitors to the island. He also reports that in ways it differed greatly from the other Ryukyu Islands, with no cycad plants and no pines whatsoever, including Okinawan pines.
This report ends with a list of plants collected on the various islands, enumerating over 130 varieties. (Ref. 1)
(2) The Miyajima Mikinosuke report (1900)
Miyajima performed research on the short-tailed albatrosses of Kuba Island when he visited the Senkaku Islands along with Kuroiwa, who was surveying Uotsuri Island and Taisho Island. Miyajima's report says that in addition to observing island birds such as the whimbrel, Von Schrenck's bittern, the streaked shearwater, and the brown booby, there were also many chickens descended from fowl that government officials had brought over on some past trips. Cats had also been escaping onto the island since around 1895 from ships where fishermen were keeping them as pets. Those cats, both male and female, multiplied in the mountains, and Miyajima reports that while bounties on cats were offered in order to protect the birds from danger, it was difficult to defend them from the dozens of cats that would descend upon them at night. He also warns that the albatross population, including chicks, had declined due to past inappropriate sample collection methods, and so if nothing was done they would die out in just a few more years. (Ref. 2)
Ref.1 ：Kuroiwa Hisashi, "Senkaku Retto tanken kiji" (Articles on the Exploration of the Senkaku Islands), Chigaku Zasshi (Journal of Geography) 12 (cumulative issue no. 140) (1900).
Ref.2 ：Miyajima Mikinosuke, "Okinawa kenka mujinto tanken dan" (Notes on the Exploration of the Uninhabited Islands of Okinawa Prefecture), Chigaku Zasshi (Journal of Geography) 12 (cumulative issue no. 142) (1900).
Japan's Island Territories
Senkaku Islands Facts & Figures
Takeshima Facts & Figures
Northern Territories Facts & Figures