Managing Conservation Reliant Species: Hawai'i's Endangered Endemic Waterbirds

Jared G Underwood,Kim Uyehara,Mike Silbernagle,Mike Nishimoto,David L Roberts

doi:10.1371/journal.pone.0067872

Jared G Underwood, Kim Uyehara + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0067872

Copy DOI

Journal: PLoS ONE	Publication Date: Jun 25, 2013
Citations: 33	License type: CC0 1.0

Affiliation: United States Fish and Wildlife Service

Abstract

Hawai'I's coastal plain wetlands are inhabited by five endangered endemic waterbird species. These include the Hawaiian Coot ('alae ke'oke'o), Hawaiian Duck (koloa maoli), Hawaiian Stilt (ae'o), Hawaiian Gallinule (Moorhen) ('alae 'ula), and Hawaiian Goose (nēnē). All five species are categorized as being “conservation reliant.” The current strategy to recover these endangered birds includes land protection and active management of wetlands. To assess the effectiveness of the current management paradigm, we compared species population trends across the state to those on six actively managed wetland national wildlife refuges (Refuges) thought to be critical for the survival of these endangered species. To perform the evaluation we relied on systematic semiannual population counts that have been conducted across most wetlands in the state and monthly population counts that have occurred on Refuges during the same time period. We found that statewide and Refuge populations of the Hawaiian Coot, Stilt and Gallinule have rebounded from historic lows and over the last 20 years have slowly increased or remained stable. We also documented that Refuges are important to each species year-round and that a disproportionately larger percentage of the population for each species is found on them. Understanding of why Refuges successfully house a disproportionate percentage of these “conservation reliant” species can inform current and future conservation efforts as well as ensure long-term population viability for these species.

Highlights

Hawai’i is home to more endangered species than any other state in the United States [1]
This represents a 31% reduction from the total estimated in 1780, with the majority of remaining coastal plain wetland areas degraded by altered hydrology, invasive species, and contaminants [2,7]
To assess the importance of Refuges and their associated management practices to waterbird populations, we evaluated three metrics: long-term population trends, percentage of the population for each species found on Refuges over time, and seasonal use of Refuges

Summary

Introduction

Hawai’i is home to more endangered species than any other state in the United States [1]. Listed species in Hawai’i include five endangered endemic waterbirds, the Hawaiian Coot (’alae ke’oke’o; Fulica alai), Hawaiian Duck (koloa maoli; Anas wyvilliana), Hawaiian Stilt (ae’o; Himantopus mexicanus knudseni), Hawaiian Gallinule (Moorhen) (’alae ’ula; Gallinula galeata sandvicensis), and Hawaiian Goose (nene; Branta sandvicensis) Endangerment of these five species has been attributed to a loss or modification of wetland habitats, introduced plants and predators, avian diseases, altered hydrology, hybridization, and historic overhunting [2,3]. Faced by this suite of cumulative threats, these endangered Hawaiian birds have recently been categorized as ‘‘conservation reliant’’, which implies that they will require active management into perpetuity [4,5,6]. It has generally been proposed that birds disperse across these wetlands during the rainy season (October- March) and congregate in key wetlands during the dry season (AprilSeptember) [2,3]

Methods

Results

Conclusion