André M, Kamminga C. 2000. Rhythmic dimension in the echolocation click trains of sperm whales: A possible function of identification and communication. Journal of the Marine Biological Association of the United Kingdom 80: 163-169.
Baker-Médard MSA, Baker MC, Logue DM. 2013. Chorus song of the Indri (Indri: Primates, Lemuridae): group differences and analysis of within-group vocal interactions. International Journal of Comparative Psychology 26: 241-255.
Bradbury JW, Vehrencamp SL. 1998. Principles of Animal Communication. Sunderland, Sinauer Associates.
Brockelman WY, Schilling D. 1984. Inheritance of stereotyped gibbon calls. Nature 312: 634-636.
Carlson NV, Greene E, Templeton CN. 2020. Nuthatches vary their alarm calls based upon the source of the eavesdropped signals. Nature Communications 11: 526.
de Oliveira David JA, Zefa E, Fontanetti CS. 2003. Cryptic species of Gryllus in the light of bioacoustic (Orthoptera: Gryllidae). Neotropical Entomology 32: 75-80.
De Gregorio C, Zanoli A, Valente D, et al. 2019. Female indris determine the rhythmic structure of the song and sustain a higher cost when the chorus size increases. Current Zoology 65: 89-97.
De Gregorio C, Carugati F, Estienne V, et al. 2021a. Born to sing! Song development in a singing primate. Current Zoology 67: 597-608.
De Gregorio C, Valente D, Raimondi R, et al. 2021b. Categorical rhythms in a singing primate. Current Biology 31: 1379-1380.
De Gregorio C, Carugati F, Valente D, et al. 2022. Notes on a tree: reframing the relevance of primate choruses, duets, and solo songs. Ethology Ecology & Evolution 34: 205-219.
Egnor SER, Miller C, Hauser MD. 2004. Nonhuman primate communication. Encyclopedia of Language and Linguistics. Amsterdam, Elsevier.
Filippi P, Hoeschele M, Spierings M, Bowling, DL. 2019. Temporal modulation in speech, music, and animal vocal communication: evidence of conserved function. Annals of the New York Academy of Sciences 1453: 99-113.
Fitch WT. 2010. The Evolution of Language. Cambridge, Cambridge University Press.
Gamba M, Favaro L, Torti V, Sorrentino V, Giacoma C. 2011. Vocal tract flexibility and variation in the vocal output in wild indris. Bioacoustics: the International Journal of Animal Sound and Its Recording 20: 251-265.
Gamba M, Colombo C, Giacoma C. 2012. Acoustic cues to caller identity in lemurs: a case study. Journal of Ethology 30: 191-196.
Gamba M, Torti V, Estienne V, et al. 2016. The Indris Have Got Rhythm! Timing and Pitch Variation of a Primate Song Examined between Sexes and Age Classes. Frontiers in Neuroscience 10:249.
Geissmann T, Mutschler T. 2006. Diurnal distribution of loud calls in sympatric wild indris (Indri indri) and ruffed lemurs (Varecia variegata): implications for call functions. Primates 47: 393-396.
Giacoma C, Sorrentino V, Rabarivola C, Gamba M. 2010. Sex differences in the song of Indri indri. International Journal of Primatology 31: 539-551.
Haimoff EH. 1986. Convergence in the duetting of monogamous Old World primates. Journal of Human Evolution 15: 51-59.
Hauser MD, Chomsky N, Fitch WT. 2002. The faculty of language: what is it, who has it, and how did it evolve? Science 298:1569-79.
Herrera JP, Dávalos LM. 2016. Phylogeny and Divergence Times of Lemurs Inferred with Recent and Ancient Fossils in the Tree. Systematic Biology 65: 772-791.
Kotz SA, Ravignani A, Fitch WT. 2018. The Evolution of Rhythm Processing. Trends in Cognitive Sciences 22 :, 896-910.
Knörnschild M, Feifel M, Kalko EVK. 2013. Mother-offspring recognition in the bat Carollia perspicillata. Animal Bbehaviour 86: 941-948.
Macedonia JM, Taylor LL. 1985. Subspecific divergence in a loud call of the ruffed lemur (Varecia variegata). American Journal of Primatology 9: 295-304.
Maretti G, Sorrentino V, Finomana A, Gamba M, Giacoma C. 2010. Not just a pretty song: an overview of the vocal repertoire of Indri indri. Journal of Anthropological Sciences 88: 151-165
Mathevon N, Casey C, Reichmuth C, Charrier I. 2017. Northern elephant seals memorize the rhythm and timbre of their rivals’ voices. Current Biology 27: 2352-2356.
Norton P, Scharff C. 2016. “Bird Song Metronomics”: Isochronous Organization of Zebra Finch Song Rhythm. Frontiers in Neuroscience.
Okanoya K. 2007. Language evolution and an emergent property. Current opinion in neurobiology 17: 271-276.
Pollock JI. 1975. The Social Behaviour and Ecology of Indri indri. London University (Doctoral dissertation).
Pollock JI. 1986. The song of the Indris (Indri indri; Primates: Lemuroidea): natural history, form and function. International Journal of Primatology 7: 225-267.
Pouw W, Proksch S, Drijvers L, et al. 2021. Multilevel rhythms in multimodal communication. Philosophical Transactions B 376: 20200334.
Powzyk JA. 1997. The socio-ecology of two sympatric indriids : Propithecus diadema diadema and Indri indri, a comparison of feeding strategies and their possible repercussions on species-specific behaviors. Duke University (Doctoral dissertation)
Ravignani A, Thompson B, Lumaca M, Grube M. 2018. Why Do Durations in Musical Rhythms Conform to Small Integer Ratios? Frontiers in Computational Neuroscience 12:86.
Ravignani A, Dalla Bella S, Falk S, Kello CT, Noriega, Kotz SA. 2019. Rhythm in speech and animal vocalizations: a cross-species perspective. Annals of the New York Academy of Sciences 1453: 79-98.
Roeske TC, Tchernichovski O, Poeppel D, Jacoby N. 2020. Categorical rhythms are shared between songbirds and humans. Current Biology 30: 3544–3555.
Savage P, Brown S, Sakai E, Currie T. 2015. Statistical universals reveal the structures and functions of human music. Proceedings of the National Academy of Sciences 112: 8987-8892.
Seyfarth RM, Cheney DL. 2003. Signalers and receivers in animal communication. Annual Review of Psychology, 54: 145-173
Sorrentino V, Gamba M, Giacoma C. 2013. A Quantitative Description of the Vocal Types Emitted in the Indri’s song. In J Masters, M Gamba, & F Génin F (Eds.), Leaping Ahead: Advances in Prosimian Biology (pp. 315-322). New York, Springer Science + Business Media
Spezie G, Torti V, Bonadonna G, De Gregorio C, Valente D, Giacoma C, Gamba M. 2022.
Evidence for acoustic discrimination in lemurs: a playback study on wild indris (Indri indri). Current Zoology 68: 1–9
Stivers T, Enfield NJ, Brown P, et al. 2009. Universals and cultural variation in turn-taking in conversation. Proceedings of the National Academy of Sciences 106:10587–10592.
Thalmann U, Geissmann T, Simona A, Mutschler T. 1993. The indris of Anjanaharibe-Sud, northeastern Madagascar. International Journal of Primatology 14: 357-381.
Torti V, Gamba M, Rabemananjara ZH, Giacoma C. 2013. The songs of the indris (Mammalia: Primates: Indridae): Contextual variation in the long‐distance calls of a lemur. Italian Journal of Zoology 80: 596-607.
Torti V, Bonadonna G, De Gregorio C, Valente D, Randrianarison RM, Friard O, Giacoma C. 2017. An intra‐population analysis of the indris' song dissimilarity in the light of genetic distance. Scientific Reports 7: 10140.
Torti V, Valente D, De Gregorio C, et al. 2018. Call and be counted! Can we reliably estimate the number of callers in the indri’s (Indri indri) song? PLoS ONE 13: e0201664.
Valente D, De Gregorio C, Torti V, et al. 2019. Finding Meanings in Low Dimensional Structures: Stochastic Neighbor Embedding Applied to the Analysis of Indri indri Vocal Repertoire. Animals 9.
Valente D, De Gregorio C, Favaro L, et al. 2021. Linguistic laws of brevity: conformity in Indri indri. Animal Cognition 24: 897-906.
Valente D, Miaretsoa L, Anania A, et al. 2022. Comparative analysis of vocalisations of diademed sifakas (Propithecus diadema) and indris (Indri indri). International Journal of Primatology 43: 733-751.
Zanoli A, De Gregorio C, Valente D, et al. 2020. Sexually dimorphic phrase organization in the song of the indris (Indri indri). American Journal of Primatology 82:e23132.



