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

Apalopteron Familiare和Carduelis Sinica kittlitze是博宁群岛特有的濒危物种。它们在Hahajima群岛的主岛Hahajima上的丰度已经被许多研究人员和机构反复调查。然而，目前还没有一种既方便又可靠的方法来评价该物种的丰富度。在本工作中，我探索了一种方便可靠的物种丰富度评估方法：无翅目昆虫属：作者称之为“鸣叫法”，是一种计算黎明前鸣叫的雄鸟数量的方法。大多数地域性(繁育)雄鸟只在清晨大声歌唱20-30分钟，尽管它们只在白天再次歌唱。结果表明，“鸣鸣法”是一种简便、可靠的估计繁殖雄鱼数量的方法。2)中华锦鸡儿：这是中华锦鸡儿的一个濒危亚种。长期以来，主要对Hahajima的主要部分进行调查。但这些鸟主要分布在Hahajima的大片小岛上，有时还分布在Hahajima的南部。因此，为了了解该物种的丰度，应对这些地区的中华锦鸡儿的数量进行统计。

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.