Linking occupancy surveys with habitat characteristics to estimate abundance and distribution in an endangered cryptic bird

Biodiversity and Conservation
By: , and 

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Abstract

Accurate estimates of the distribution and abundance of endangered species are crucial to determine their status and plan recovery options, but such estimates are often difficult to obtain for species with low detection probabilities or that occur in inaccessible habitats. The Puaiohi (Myadestes palmeri) is a cryptic species endemic to Kauaʻi, Hawai‘i, and restricted to high elevation ravines that are largely inaccessible. To improve current population estimates, we developed an approach to model distribution and abundance of Puaiohi across their range by linking occupancy surveys to habitat characteristics, territory density, and landscape attributes. Occupancy per station ranged from 0.17 to 0.82, and was best predicted by the number and vertical extent of cliffs, cliff slope, stream width, and elevation. To link occupancy estimates with abundance, we used territory mapping data to estimate the average number of territories per survey station (0.44 and 0.66 territories per station in low and high occupancy streams, respectively), and the average number of individuals per territory (1.9). We then modeled Puaiohi occupancy as a function of two remote-sensed measures of habitat (stream sinuosity and elevation) to predict occupancy across its entire range. We combined predicted occupancy with estimates of birds per station to produce a global population estimate of 494 (95% CI 414–580) individuals. Our approach is a model for using multiple independent sources of information to accurately track population trends, and we discuss future directions for modeling abundance of this, and other, rare species.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Linking occupancy surveys with habitat characteristics to estimate abundance and distribution in an endangered cryptic bird
Series title Biodiversity and Conservation
DOI 10.1007/s10531-017-1313-0
Volume 26
Issue 7
Year Published 2017
Language English
Publisher Springer
Contributing office(s) Pacific Island Ecosystems Research Center
Description 15 p.
First page 1525
Last page 1539