Evol Ecol https://doi.org/10.1007/s10682-018-9934-7 1 3 ORIGINAL PAPER Vocal variation in Chiroxiphia boliviana (Aves; Pipridae) along an Andean elevational gradient Mariana Villegas 1,3  · John G. Blake 1  · Kathryn E. Sieving 1  · Bette A. Loiselle 1,2 Received: 9 November 2017 / Accepted: 24 March 2018 © Springer International Publishing AG, part of Springer Nature 2018 Abstract Bird vocalizations are likely shaped both by natural and sexual selection. Here we test the sensory-drive hypothesis, which states that communication signals diverge as a direct adaptation to the signaling environment and can evolve to minimize degradation and maximize transmission. We examined the efects of elevation and other habitat variables on variation in vocalizations of Chiroxiphia boliviana (Aves, Pipridae) along an elevational gradient (1300–2500 m) in cloud and humid montane forests in the Andes of Bolivia. We also conducted sound transmission experiments to determine if reverberation and attenu- ation changed along the gradient. Reverberation increased at higher elevations, and atten- uation decreased at higher elevations and increased for higher frequencies. We recorded vocalizations from ~ 50 individuals throughout the elevational gradient and examined vari- ation in duration and bandwidth of short calls (used as contact calls between males), 2 dis- play calls (advertisement for females) and 2 types of male–male duets (including interval times between males). Duration of short calls, display 1 and duet 1 increased with eleva- tion. Bandwidth of short calls increased at mid-elevation categories and decreased at high elevations, whereas bandwidth of display 1 and duet 1 decreased with elevation. We also directly related the transmission properties to vocalizations and found that bandwidth of short calls decreased with reverberation and attenuation, bandwidth of display 2 decreased with reverberation, and duration of duet 1 both increased and decreased with attenuation (at 3 and 4 kHz, respectively). This study suggests that vocalizations by C. boliviana may be adapted to the habitat transmission properties along the elevational gradient; and perhaps Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1068 2-018-9934-7) contains supplementary material, which is available to authorized users. * Mariana Villegas mariana.villegas@gmail.com 1 Department of Wildlife Ecology and Conservation, University of Florida, 110 Newins-Ziegler Hall, PO Box 110430, Gainesville, FL 32611, USA 2 Center for Latin American Studies, University of Florida, 319 Grinter Hall, PO Box 115530, Gainesville, FL 32611, USA 3 Present Address: Instituto de Ecología, Universidad Mayor de San Andrés, La Paz, Bolivia