Rattling cisticola song features and variability across sub-Saharan Africa L. Benedict 1 & R. C. K. Bowie 2 1 School of Biological Sciences, University of Northern Colorado, Greeley, CO, USA 2 Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley, CA, USA Keywords birdsong; geographic variation; species recognition; Africa; Cisticolidae; Passeriformes. Correspondence Lauryn Benedict, University of Northern Colorado, 2480 Ross Hall – Campus Box 92, 501 20th Street, Greeley, CO 80639, USA. Email: lauryn.benedict@unco.edu Editor: Andrew Kitchener Received 7 July 2011; revised 2 December 2011; accepted 6 December 2011 doi:10.1111/j.1469-7998.2011.00890.x Abstract Quantifying bird song variation can be an important tool for ensuring accurate species identification and can provide a significant basis for understanding the evolutionary processes that shape phenotypic diversity. This study describes vari- ation in the songs of rattling cisticolas Cisticola chiniana across sub-Saharan Africa. For many cisticola species, learned songs are the most obvious phenotypic indicators of species affiliation and may also function to indicate individual quality. We examined 957 songs recorded from 61 individuals and archived in sound libraries. To assess the diversity of syllable and song types, we examined patterns of syllable use. We also measured vocalization frequency and time parameters and assessed how they vary through space. Results indicated that rattling cisticola songs are highly variable, but also have features that are species- specific. Examined songs had a relatively fixed structure containing one of three characteristic introductory note types, followed by an end phrase. Two of the introductory note types were sung across the species’ range (some 4500 km), whereas the third was only recorded in south-western Africa. End phrases gener- ated most of the diversity in songs and appeared to have an unlimited number of forms. End-phrase characteristics showed a strong geographic variation, but did not vary with elevation. Song features varied individually and geographically in ways that are consistent with evolution due to multiple selective pressures, includ- ing stabilizing selection for species recognition on the introductory notes and diversifying selection on the end phrases. This pattern of lability in some song features coupled with stability in others may be a common feature of cisticola songs as it has also been found in Cisticola erythrops, a congener with a similarly broad range. Introduction The songs of birds vary spatially and temporally in a multi- tude of different ways (Podos & Warren, 2007; Catchpole & Slater, 2008). Songs are often used as a species-identifying characteristic, but may not be effective if the range of song features for any one species is not well-described. A thorough understanding of within-species song diversity is particularly important for birds with wide geographic ranges that occur in a variety of habitats. As a practical consideration, such species are likely to be sympatric with many other species, creating abundant opportunities for mis-identification. Simultane- ously, they are likely to show diversity in song characteristics due to multiple selective pressures on song form (Seddon, 2005; Podos & Warren, 2007). Evolutionarily, a large geo- graphic range allows for greater diversification due to drift (cultural or genetic) and local adaptation (Edwards et al., 2005; Price, 2007; Benedict & Bowie, 2009). Widely distrib- uted birds will necessarily occur at a range of geographic locations with varying climates, elevations and habitats, all of which have been shown to influence bird song properties (Ryan & Brenowitz, 1985; Bertelli & Tubaro, 2002; Kirschel et al., 2009). Ecologically, varied habitat features may cause diversifying selection on acoustic traits due to differing sound transmission properties of the habitat (Morton, 1975; Wiley & Richards, 1982; Slabbekoorn & Smith, 2002a). Variation in the strength and outcomes of local sexual selection can also generate diversity (Andersson, 1994). Among song-learning birds, like cisticola warblers, song form can be shaped by both genetic and cultural evolution (Slater, 1989). Rattling cisticolas Cisticola chiniana belong to a genus including 40 plus species of drab brown birds, which have long confounded recreational birders and ornithologists alike (Lynes, 1930; Ryan, 2006; Nguembock et al., 2007). Individu- als in the field and museum study skins are regularly mis- identified (R. C. K. Bowie, unpubl. data). Within this genus, Journal of Zoology Journal of Zoology. Print ISSN 0952-8369 96 Journal of Zoology 287 (2012) 96–103 © 2012 The Authors. Journal of Zoology © 2012 The Zoological Society of London