ORNITOLOGIA NEOTROPICAL 25: 219–230, 2014 © The Neotropical Ornithological Society A QUANTITATIVE DESCRIPTION OF VOCALIZATIONS AND VOCAL BEHAVIOUR OF THE RUSTY-CROWNED GROUND- SPARROW (MELOZONE KIENERI) Luis Sandoval1,2 & Daniel J. Mennill1 1Department of Biological Sciences, University of Windsor, Windsor, Ontario, N9B3P4, Canada. E-mail: [email protected] 2Current address: Escuela de Biología, Universidad de Costa Rica, San Pedro, San José, Costa Rica, CP 2090. Resumen. – Descripción cuantitativa de las vocalizaciones y el comportamiento vocal del Cuatro- ojos Gorra Naranja (Melozone kieneri). – Muchas especies de emberízidos (Emberizidae) han servido como modelo para entender el canto y el comportamiento vocal en aves. En contraste, el comporta- miento vocal y los repertorios vocales para la mayoría de especies tropicales de emberízidos son poco conocidos, aunque la diversidad de especies sea mayor. Nosotros presentamos la primera descripción cuantitativa del repertorio y el comportamiento vocal del Cuatro-ojos de Gorra Naranja (Melozone kie- neri), endémico de México. También proveemos información sobre el efecto de la distribución espacial en la similitud de los repertorios, así como la variación diaria de las vocalizaciones, todo esto basado en grabaciones focales, autónomas, y oportunísticas en una población de El Tuito, Jalisco, México. Nues- tros resultados demuestran que el Cuatro-ojos de Gorra Naranja produce tres categorías de vocalizacio- nes - llamadas, cantos solos y duetos - como ocurre en otras especies de Melozone. Encontramos que los cantos solo y los duetos en esta especie presentaron características intermedias a especies de Melozone que se distribuyen más al norte o sur. La similitud de los repertorios entre machos cercanos fue mayor, sugiriendo que el aprendizaje del canto puede ocurrir después del establecimiento territorial. Las llamadas y los cantos presentaron un pico marcado temprano en la mañana indicando que esta especie participa de los coros del amanecer. Este estudio es la primera descripción cuantitativa de las vocalizaciones del Cuatro-ojos de Gorra Naranja, el cual generó importante información descriptiva en esta especie poca estudiada de Melozone Neotropical. Abstract. – Many species of sparrows (Emberizidae) in the temperate zone provide model systems for understanding bird song and singing behaviour. In contrast, the vocal repertoire and vocal behaviour for most tropical sparrows is poorly understood, in spite of their impressive biodiversity. We present here the first detailed quantitative description of vocal repertoires and vocal behaviour of the Rusty-crowned Ground-sparrow (Melozone kieneri), an endemic Mexican sparrow. We provide information on the effect of territory spacing on song repertoire-use and details of the diel pattern of variation in vocal output, using focal, autonomous, and opportunistic recordings of birds in El Tuito, Jalisco, Mexico. Our results demon- strate that Rusty-crowned Ground-sparrows produce three distinct categories of vocalizations – calls, solo songs, and duets – as in other Melozone ground-sparrows. We found that solo songs and duets in this species showed an acoustic structure intermediate to other northern and southern Melozone ground- sparrows. Patterns of repertoire-use in male solo songs were highly similar between males holding nearby territories, suggesting that song learning may occur after territory establishment. The diel pattern for output of calls and solo songs showed a pronounced peak early in the morning, indicative of dawn- chorus singing behaviour. This study provides the first quantitative investigation of Rusty-crowned 219 SANDOVAL & MENNILL Ground-sparrow vocalizations, providing important descriptive information on this little-studied Neotropi- cal Melozone species. Accepted on 13 August 2014. Key words: Rusty-crowned Ground-sparrow, Melozone kieneri, bird calls, diel variation, duets, Emberi- zidae, solo songs, sparrows. INTRODUCTION research priority because such studies will allow us to conduct comparative studies Decades of investigations of temperate spar- between tropical and temperate species, to rows (family: Emberizidae) have led to the better understand the phylogenetic relation- development of many key principles of avian ships between species (Cadena & Cuervo acoustic communication (e.g., vocalizations, 2010), and may lead to additional important vocal behaviour) (Marler 2004a, Catchpole & insights that will further expand our under- Slater 2008). For example, White-crowned standing of animal vocal behaviour generally. Sparrows (Zonotrichia leucophrys) were the initial In this investigation, we studied the Rusty- species used to examine geographic variation crowned Ground-sparrow (Melozone kieneri). at both broad and local scales (Marler & This endemic Mexican sparrow inhabits both Tamura 1962) which lead to the study of cul- deciduous and dry forest habitat from sea tural transmission in animals that learn their level to 2000 m a.s.l., with a range extending vocalizations (Marler 1970, 2004b). Song syn- from the south of Sonora to western Oaxaca, tax was first studied in Swamp Sparrows and the interior of Jalisco (Miller et al. 1957, (Melospiza georgiana), providing evidence that Howell & Webb 1995, Rising 2011). Pairs of animals arrange their vocalizations with spe- Rusty-crowned Ground-sparrows appear to cies-specific syntactical structure, much like defend territories using vocalizations, as do human language (Marler & Pickert 1984). Our the other tropical species in the genus Melo- understanding of the production of overtones zone (Benedict & McEntee 2009; Sandoval et (Nowicki 1987), the function of graded sig- al. 2013, 2014), although their vocal reper- nals (Beecher & Campbell 2005, Searcy & toires and behaviour has never been Beecher 2009), and the dynamics of conven- described in detail (Howell & Webb 1995, tional signals during aggressive interactions Rising 2011). With this study our goal is to (Vehrencamp 2001) arose from seminal stud- present the first quantitative description of ies of Song Sparrows (Melospiza melodia). the vocal repertoire and vocal behaviour of Information on the vocal repertoires and the Rusty-crowned Ground-sparrow. In addi- vocal behaviour for the majority of tropical tion, we investigate the relationship between sparrows, in contrast, is limited or absent. territory spacing and song type sharing, and One exception is the Rufous-collared Spar- describe the diel pattern of variation in vocal row (Zonotrichia capensis); this widely studied output. tropical sparrow has been instrumental in enhancing our understanding of geographic METHODS variation and the relationship between habitat and population divergence in vocalizations Field recordings. We recorded Rusty-crowned (e.g., King 1972, Handford 1988, Handford & Ground-sparrows at Rancho Primavera, El Lougheed 1991, Kopuchian et al. 2004, Dan- Tuito, Jalisco state, Mexico (20°21’N, ner et al. 2011). Further investigations of the 105°20’W, 585 m a.s.l.). We collected record- vocalizations and vocal behaviour of other ings from 27 June to 3 July 2012, during the tropical sparrow species is an important species’ breeding season (Rowley 1962). Our 220 BIOACOUSTICS OF THE RUSTY-CROWNED GROUND-SPARROW field observations confirmed that some of the sun rises at approximately 07:05 h during the study birds were actively breeding during the studied period); each pair was recorded on recording period: we observed adults carrying one day using this technique (N = 13 pairs). nesting material in two of the recorded pairs, Second, we used autonomous digital record- and for two other pairs we observed behav- ers (Wildlife Acoustics Song Meters model iour consistent with incubation (i.e., one SM1) set up inside birds’ territories to record member of the pair disappeared after a period birds for a period that varied from 6 to 15 of foraging early during the day). hours (mean ± SE: 10.33 ± 2.18 h; N = 5 Recorded individuals were not colour- pairs). All of these recordings included a con- banded; we distinguished between territorial tinuous period from 07:00 to 09:00 h, when pairs based on their location (we collected this species is most vocally active (see GPS coordinates of the centre of each identi- Results). Third, we collected opportunistic fied territory). Based on previous field obser- recordings between 08:00 and 19:00 h while vations of this species, and observations of we were walking nearby or inside birds’ terri- colour-banded study populations of a closely tories, when we detected birds vocalizing; we related species (White-eared Ground-sparrow, collected 03:35 h of recordings using this Melozone leucotis; Sandoval et al. 2013, 2014; approach. Focal and opportunistic recordings Sandoval 2014), we considered birds to were collected with a shotgun microphone belong to a distinct pair when they were > 50 (Sennheiser ME66/K6) connected to a digital m away from the centre of the neighbouring recorder (Marantz PMD660 and Marantz pair’s territory. Daily, we monitored and con- PMD661), and with a parabola-mounted firmed the presence of previously recorded omnidirectional microphone (23 in Telinga pairs at the same locations. These observa- parabola with a Sennheiser ME62/K6 micro- tions made us confident that pairs recorded phone) and digital recorder (Zoom H4n). All on different days were distinct and that pairs recordings were collected in WAV format, occupied the same territories throughout our with 16 bit accuracy and a 44.1 kHz