Why Stable Populations of Conserved Bird Species May Still Be Considered Vulnerable: The Nihoa Finch (Telespiza Ultima) As a Case Study

Islands host a high percentage of endemic species due to their ecosystems having evolved in isolation [1]. In the absence of natural predators and resistance to alien diseases, the flora and fauna of islands are considered more fragile than mainland species and prone to impacts from non-native species [2]. The ecosystems of the Hawaiian Islands, one of the world’s most isolated archipelagos, have a diverse and highly endemic wildlife [3], first challenged 1200 years ago by rats, pigs and dogs brought by Polynesians, followed a thousand years later by European colonists with more rats, cattle, sheep, goats, cats, parasites and diseases [4]. Numerous Hawaiian species are declining and many, including more than half of its endemic birds [5], have fallen to extinction due to anthropogenic factors. The status of decline and sustainability of various bird populations remains a current concern [6].