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Versatility and stereotypy of free-tailed bat songs.

Bohn KM, Schmidt-French B, Schwartz C, Smotherman M, Pollak GD - PLoS ONE (2009)

Bottom Line: Second, we found that although song construction was similar across regions, the number of syllables within phrases, and the number and order of phrases in songs varied greatly within and among individuals.We found broad scale phrase-order rules and certain higher order combinations that were highly preferred.We conclude that free-tailed bat songs are composed of highly stereotyped phrases hierarchically organized by a common set of syntactical rules.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA. kbohn@bio.tamu.edu

ABSTRACT
In mammals, complex songs are uncommon and few studies have examined song composition or the order of elements in songs, particularly with respect to regional and individual variation. In this study we examine how syllables and phrases are ordered and combined, ie "syntax", of the song of Tadarida brasiliensis, the Brazilian free-tailed bat. Specifically, we test whether phrase and song composition differ among individuals and between two regions, we determine variability across renditions within individuals, and test whether phrases are randomly ordered and combined. We report three major findings. First, song phrases were highly stereotyped across two regions, so much so that some songs from the two colonies were almost indistinguishable. All males produced songs with the same four types of syllables and the same three types of phrases. Second, we found that although song construction was similar across regions, the number of syllables within phrases, and the number and order of phrases in songs varied greatly within and among individuals. Last, we determined that phrase order, although diverse, deviated from random models. We found broad scale phrase-order rules and certain higher order combinations that were highly preferred. We conclude that free-tailed bat songs are composed of highly stereotyped phrases hierarchically organized by a common set of syntactical rules. However, within global species-specific patterns, songs male free-tailed bats dynamically vary syllable number, phrase order, and phrase repetitions across song renditions.

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The distribution of song lengths at the two locations.The frequency of songs with 2 through 7 or more phrases at Austin (white bars, N = 200) and College Station (filled bars, N = 91). The distribution of song lengths is highly similar at the two locations.
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pone-0006746-g003: The distribution of song lengths at the two locations.The frequency of songs with 2 through 7 or more phrases at Austin (white bars, N = 200) and College Station (filled bars, N = 91). The distribution of song lengths is highly similar at the two locations.

Mentions: Next we compared features of entire songs, (eg the total number of phrases, the number of buzzes etc.) at the two locations and found that song features were generally similar (Table 1, Song Variables). However, we found two minor regional differences. First, the proportion of songs with buzzes was greater in College Station (80%) than in Austin (40%; Table 1). Second, Austin bats emitted a greater number of songs composed only of chirps, i.e., single phrase songs, than did College Station bats (Table 1). In Austin, 37% of songs were chirp-only songs (N = 319 total songs) compared with only 2 % in College Station (N = 93 total songs). This resulted in a larger number of phrases per song in College Station compared to Austin (Table 1). When we excluded chirp-only songs from the analysis, there was no difference in the number of phrases per song between locations (Table 1), nor was there a difference between locations in the distribution of songs with different numbers of phrases (χ2 = 2.11, P = 0.84, df = 5, Fig. 3, chirp-only songs excluded). Thus, although we found a few minor differences in song composition, overall song construction and diversity are remarkably similar at the two locations.


Versatility and stereotypy of free-tailed bat songs.

Bohn KM, Schmidt-French B, Schwartz C, Smotherman M, Pollak GD - PLoS ONE (2009)

The distribution of song lengths at the two locations.The frequency of songs with 2 through 7 or more phrases at Austin (white bars, N = 200) and College Station (filled bars, N = 91). The distribution of song lengths is highly similar at the two locations.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2727915&req=5

pone-0006746-g003: The distribution of song lengths at the two locations.The frequency of songs with 2 through 7 or more phrases at Austin (white bars, N = 200) and College Station (filled bars, N = 91). The distribution of song lengths is highly similar at the two locations.
Mentions: Next we compared features of entire songs, (eg the total number of phrases, the number of buzzes etc.) at the two locations and found that song features were generally similar (Table 1, Song Variables). However, we found two minor regional differences. First, the proportion of songs with buzzes was greater in College Station (80%) than in Austin (40%; Table 1). Second, Austin bats emitted a greater number of songs composed only of chirps, i.e., single phrase songs, than did College Station bats (Table 1). In Austin, 37% of songs were chirp-only songs (N = 319 total songs) compared with only 2 % in College Station (N = 93 total songs). This resulted in a larger number of phrases per song in College Station compared to Austin (Table 1). When we excluded chirp-only songs from the analysis, there was no difference in the number of phrases per song between locations (Table 1), nor was there a difference between locations in the distribution of songs with different numbers of phrases (χ2 = 2.11, P = 0.84, df = 5, Fig. 3, chirp-only songs excluded). Thus, although we found a few minor differences in song composition, overall song construction and diversity are remarkably similar at the two locations.

Bottom Line: Second, we found that although song construction was similar across regions, the number of syllables within phrases, and the number and order of phrases in songs varied greatly within and among individuals.We found broad scale phrase-order rules and certain higher order combinations that were highly preferred.We conclude that free-tailed bat songs are composed of highly stereotyped phrases hierarchically organized by a common set of syntactical rules.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA. kbohn@bio.tamu.edu

ABSTRACT
In mammals, complex songs are uncommon and few studies have examined song composition or the order of elements in songs, particularly with respect to regional and individual variation. In this study we examine how syllables and phrases are ordered and combined, ie "syntax", of the song of Tadarida brasiliensis, the Brazilian free-tailed bat. Specifically, we test whether phrase and song composition differ among individuals and between two regions, we determine variability across renditions within individuals, and test whether phrases are randomly ordered and combined. We report three major findings. First, song phrases were highly stereotyped across two regions, so much so that some songs from the two colonies were almost indistinguishable. All males produced songs with the same four types of syllables and the same three types of phrases. Second, we found that although song construction was similar across regions, the number of syllables within phrases, and the number and order of phrases in songs varied greatly within and among individuals. Last, we determined that phrase order, although diverse, deviated from random models. We found broad scale phrase-order rules and certain higher order combinations that were highly preferred. We conclude that free-tailed bat songs are composed of highly stereotyped phrases hierarchically organized by a common set of syntactical rules. However, within global species-specific patterns, songs male free-tailed bats dynamically vary syllable number, phrase order, and phrase repetitions across song renditions.

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