Semester

Spring

Date of Graduation

2013

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Robert C. Whitmore

Committee Co-Chair

Angelika Nelson

Committee Member

Petra B. Wood

Abstract

Bird song characteristics are unique for each species, but songs are not identical among con-specific individuals and variations may occur at different geographic scales throughout a species distribution. Geographic song variation is common in many species, particularly in Passerines due to their song-learning behavior. Among Wood Warblers (Fam. Paruliade), The Yellow Warbler ( Setophaga petechia) is one of the most widespread and geographically diverse species. It is comprised by three groups of several subspecies which represent a great variety on morphological traits, mainly on plumage coloration. Variations on behavioral traits, such as songs, have also been found in this species. Most research on geographic vocal variation has been done on subspecies of the Northern Yellow Warbler (aestiva group) but little has been published about the songs of tropical subspecies of the Mangrove Warbler (erithachorides group).;The purpose of this study is to describe the songs of the Mangrove Warblers of Northwestern Mexico and evaluate geographic variation of song on the subspecies Setophaga petechia castaneiceps and S. p rhizophorae. I recorded and analyzed the songs of 49 males from several locations throughout the distribution of both subspecies.;I described the songs of the mangrove warblers based on their general characteristics. I found that their songs are comprised by a sequence of notes that lasts about 1.5 +/- 0.9 seconds and falls between a frequency range of 2.3 +/- 0.3 -- 7.5 +/- 1.1 kHz. The arrangement of the notes exhibit an introductory, middle and ending part of the song. The introductory part is typically formed by a sequence of more or less 3 +/- 1.27 identical notes, the middle part is formed by a sequence of varied notes and the ending part is characterized by a unique note which can either increase or decrease in frequency from its beginning to its end. According to this last note, all songs of the Mangrove Warblers were classified into accented ending songs (AES) or unaccented ending songs (UES) and 229 different song types were found among both of these categories. I found that a males' repertoire can be comprised by about 7 +/- 2.7 song types of both of these categories.;I examined geographic variation of song within and between subspecies based on vocal variation and song repertoire sharing, expecting to find greater geographic variation between subspecies than within each. I found that geographic variation of song is mostly related to UES. Although repertoire sharing occurs on both song categories, only UES are shared throughout longer geographic distances other than between neighboring males. Also, vocal variation was determined by UES, particularly by its introductory part. Dialect among localities was based on its distinction in frequency while differences between subspecies were given by its temporal characteristics. The S. p rhizophorae subspecies sings the introductory part of UES faster than the S. p castaneiceps subspecies.;The vocal differentiation between S. petechia castaneiceps and S. p rhizophorae could be useful to support subspecific recognition. However it is necessary to consider that this distinction could be related to differences in ecological factors, such as habitat characteristics, population density or breeding conditions.

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