Available data support protection of the Southwestern Willow Flycatcher under the Endangered Species Act

The Condor
By: , and 

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Abstract

Zink (2015) argued there was no evidence for genetic, morphological, or ecological differentiation between the federally endangered Southwestern Willow Flycatcher (Empidonax traillii extimus) and other Willow Flycatcher subspecies. Using the same data, we show there is a step-cline in both the frequency of a mtDNA haplotype and in plumage variation roughly concordant with the currently recognized boundary between E. t. extimus and E. t adastus, the subspecies with which it shares the longest common boundary. The geographical pattern of plumage variation is also concordant with previous song analyses differentiating those 2 subspecies and identified birds in one low-latitude, high-elevation site in Arizona as the northern subspecies. We also demonstrate that the ecological niche modeling approach used by Zink yields the same result whether applied to the 2 flycatcher subspecies or to 2 unrelated species, E. t. extimus and Yellow Warbler (Setophaga petechia). As a result, any interpretation of those results as evidence for lack of ecological niche differentiation among Willow Flycatcher subspecies would also indicate no differentiation among recognized species and would therefore be an inappropriate standard for delineating subspecies. We agree that many analytical techniques now available to examine genetic, morphological, and ecological differentiation would improve our understanding of the distinctness (or lack thereof) of Willow Flycatcher subspecies, but we argue that currently available evidence supports protection of the Southwestern Willow Flycatcher under the Endangered Species Act.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Available data support protection of the Southwestern Willow Flycatcher under the Endangered Species Act
Series title The Condor
DOI 10.1650/CONDOR-15-71.1
Volume 118
Issue 2
Year Published 2016
Language English
Publisher Cooper Ornithological Society
Publisher location Santa Clara, CA
Contributing office(s) Southwest Biological Science Center
Description 11 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title The Condor
First page 289
Last page 299
Online Only (Y/N) N
Additional Online Files (Y/N) N