Boyd Deep Canyon Desert Research Center

20 May, 05 AM - 30 May, 05 AM

In songbirds, song is a learned display that conveys information about the singer?s attribute in territorial defense and/or as a potential mate (Catchpole 1982). During the breeding season, song is usually sung only by the male, while the female evaluates the song to assess the quality the male may possess as a mate (Searcy & Nowicki 2005). It has been well documented that in songbirds, females prefer to mate with males that have higher song rates and vocal performance, males that sing complex song versus simple song, and males that sing local song versus non-local song (Searcy &Nowicki 2005 and MacDougall-Shackleton et al 2009). Song is generally considered to be an honest signal of male quality with different aspects of the song portraying the different qualities the male possesses. For instance, since song output is based on energy reserves, therefore it is a reflection of the male?s current situation (e.g. territory quality or food availability) (Searcy & Nowicki 2005). Song complexity and song sharing (ability to sing local song dialect) reflect the male?s past condition because both song complexity and song sharing is dependent on the male?s song learning ability. In most songbird species, song is learned only during early development and it has been hypothesized that during that period, individuals typically undergo nutritional and other stresses, which in turn impact the development of the brain regions that are responsible for song learning and production. Therefore, chicks that fare better than other chicks will have larger repertoires and higher song sharing with the population dialect. This hypothesis is known as the developmental stress hypothesis (Nowicki et al 2000; Nowicki 2002). Also, song production in some species can reflect the male?s body size, beak length and age (Ballentine 2009). Song characteristics and production vary from species to species along with habitat type. In both the Mojave and Sonaran Deserts, most songbird species are migratory; however, the Black-throated Sparrow has been known to be resident in Southern California, able to withstand the harsh desert conditions throughout the year. How song is being used and how it functions in black-throated sparrow has been studied to some extent; however it is still unknown whether there are any correlations with habitat quality, pairing success, age, male fitness with any aspect of the male black-throated sparrow song. Heckenlively (1967, 1970) and Tuckfield (1985) were able to show some evidence that Black-throated Sparrow song is influenced by the environment; however, whether song plays a role in mate attraction or is an honest signal of male quality is unclear. In this study, I will investigate the relationship of Black-throated Sparrow song versus male quality. First, I will test if individual song characteristics are under the influence of morphological traits, such as bill size and body size. Due to the large variation in frequency in Black-throated Sparrow song, I predict that there would be a correlation with song frequency with body size and beak length. Second, I predict that if there will be correlations among song characteristics and pairing success and habitat quality. Since higher quality territories would be more abundance in food and resources, I predict that it will correlate with song output. Song complexity in some species has been shown to correlate with reproductive success; males with larger repertoires obtained larger territories and paired earlier than males with smaller repertoires (Mockingbird (Howard 1974); Song Sparrow (Reid et al 2004); European Startling (Mountjoy & Lemon 1991); therefore, I predict that males that have more complex song will pair earlier and have higher quality territories. Lastly, I predict that song complexity and song output will correlate with male parental care. Males with larger repertoires and a higher singing rate generally are of higher quality and may contribute more food for their offspring; and I predict that this relationship will hold in the Black-Throated Sparrow. Song complexity has also been shown to predict extra-pair fertilization success, with male with that have higher repertoire size able to ?cuckold? male with lower repertoire size (Hasselquist et al 1996); for that reason, I predict that males that have lower repertoire size will be more likely to be cuckolded. This study will illustrate how song is a reliable indicator of male quality and how song functions in an understudied and declining avian species, the Black-throated Sparrow (this species has declined 63% since the 1960s due to habitat loss, wildfire, urbanization and invasive species in the desert (NAS 2009).

Visit #19668 @Boyd Deep Canyon Desert Research Center

Approved

Under Project # 20802 | Research

Male Quality in Black-throated Sparrows

graduate_student - California State University (CSU), Fullerton

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Carina Castro May 20 - 30, 2010 (11 days)

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Mayhew housing facilities 1 May 20 - 30, 2010
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Lab Space 1 May 20 - 30, 2010