Fig. 10.30

Distinguishing dialects. White‐crowned Sparrow (Zonotrichia leucophrys) songs occur in dialects; the form of a male’s song depends on where he lives. Each song form occurs within one particular area. Spectrograms A through D illustrate four different White‐crowned Sparrow dialects.

(A) White-crowned Sparrow Dialect (Eastern)
 

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(B) White-crowned Sparrow Dialect (Puget Sound)
 

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(C) White-crowned Sparrow Dialect (Gambel’s)
 

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(D) White-crowned Sparrow Dialect (Mountain)
 

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Fig. 10.32

Regional dialects. (A) Marsh Wrens (Cistothorus palustris) in eastern North America sing songs that begin with a nasal buzz, followed by repeated melodious notes. (B) In the western half of their range, Marsh Wrens produce coarse, buzzy songs that often contain raspy notes.

(A) Eastern Marsh Wren
 

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(B) Western Marsh Wren
 

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Fig. 10.34

Different song types can serve different functions. In some species, such as (A) Blue‐winged Warblers (Vermivora cyanoptera) and (B) Chestnut‐sided Warblers (Setophaga pensylvanica), songs in the first category (type 1) function in mate attraction, whereas songs in the second category (type 2) function in male–male aggression.

(A1) Blue-winged Warbler Type 1 Song
 

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(A2) Blue-winged Warbler Type 2 Song
 

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(B1) Chestnut‐sided Warbler Type 1 Song
 

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(B2) Chestnut‐sided Warbler Type 2 Song
 

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Fig. 10.35

Songs help us recognize suboscine species. Differences in song can help systematists identify cryptic species. For example, although (A) Watkins’s Antpittas (Grallaria watkinsi) and (B) Chestnut‐crowned Antpittas (Grallaria ruficapilla) occur in overlapping geographic ranges and are similar in appearance, they can be distinguished by their distinct songs.

(A) Watkins’s Antpitta
 

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(B) Chestnut‐crowned Antpitta
 

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