Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (506 KB)

Title: Are insular populations of the Philippine falconet (Microhierax erythrogenys) steps in a cline?

Author: Katzner, Todd E.; Collar, Nigel J.;

Date: 2013

Source: The Condor. 115(3): 576-583.

Publication Series: Scientific Journal (JRNL)

Description: Founder effects, new environments, and competition often produce changes in species colonizing islands, although the resulting endemism sometimes requires molecular identification. One method to identify fruitful areas for more detailed genetic study is through comparative morphological analyses. We measured 210 museum specimens to evaluate the potential morphological consequences of colonization across the Philippine archipelago by the Philippine Falconet (Microhierax erythrogenys). Measurements of both males and females differed clearly from island to island. Univariate and multivariate analysis of characteristics showed a latitudinal gradient, with the bill, wing, and tail of southern birds being larger than those of northern birds, forming the pattern of a stepped cline across a succession of islands. The stepped gradient in morphology and extensive differences between islands we observed provide evidence for multiple perspectives on phylogeny, including concordance with aggregate complexes expected on the basis of sea-level fluctuations. However, calculation of diagnosability indices did not support subspecific designations. Sex-specific dominance and dispersal patterns may explain this unusual south-to-north stepped cline, and they also provide a useful format for understanding biogeographical patterns by island. Finally, these morphological data suggest a potentially fruitful area for future genetic studies.

Keywords: colonization, dispersal, Microhierax, Philippines, stepped clines, tropical raptors

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • This publication may be available in hard copy. Check the Northern Research Station web site to request a printed copy of this publication.
  • Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact Sharon Hobrla, if you notice any errors which make this publication unusable.



Katzner, Todd E.; Collar, Nigel J. 2013. Are insular populations of the Philippine falconet (Microhierax erythrogenys) steps in a cline?. The Condor. 115(3): 576-583.


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.