Methods for evaluation of abundance in endangered birds Apalopteron familiare and Carduelis sinica kittlitze

Apalopteron familiare和Carduelis sinica kittlitze是小笠原群岛特有的濒危物种。许多研究人员和机构反复调查了波哈岛（波哈岛群岛的一个主要岛屿）上的丰富程度。然而，没有检查，不仅方便，而且可靠的方法来评估物种的丰度。本研究探索了一种简便、可靠的多度评价方法。1）家鸽：“鸣唱法”是作者提出的一种在日出前统计雄鸟鸣唱数量的方法。大多数领地（繁殖）雄性在清晨只唱大约20-30分钟，尽管它们只在白天唱。结论：“鸣唱法”是一种简便、可靠的估计繁殖雄雀数量的方法。2）中华黄雀（Carduelis sinica kittlitze）：中华黄雀（Carduelis sinica）的一个濒危岛屿亚种。长期以来，调查主要是在端岛的主要部分进行的。但这些鸟主要分布在叶海岛的大岛上，有时也分布在叶海岛的南部。因此，对这些地区的黄雀数量进行统计，以了解该物种的丰度是合适的。

Apalopteron familiare and Carduelis sinica kittlitze are endemic to the Bonin Islands and are endangered species. Their abundance on Hahajima, which is a main island of the Hahajima Islands, has been repeatedly surveyed by many researchers and institutions. However, there were no examinations on not only convenient but also reliable methods for the evaluation of abundance of the species. In the present work, I explored convenient and reliable methods for the evaluation of abundance of the species.1) Apalopteron familiare : "Song burst method" , termed by the author, was a method by which we count the number of males singing early in the morning before sunrise. Most territorial (breeding) males sing vigorously early in the morning only for about 20-30 mins, though they only rerely sing during the daytime. It is concluded that "song burst method" is very convenient and reliable to estimate the number of breeding males.2) Carduelis sinica kittlitze : This is an endangered island subspecies of Carduelis sinica. For a long period, surveys have been conducted mainly on the main part of Hahajima. But the birds were mainly distributed over large Islets of Hahajima and at times on the southern part of Hahajima. It was therefore concluded that it is appropriate to count the number of Carduelis sinica kittlitze on those areas to know abundance of this species.