1
|
|
2
|
Torti V, Valente D, De Gregorio C, Comazzi C, Miaretsoa L, Ratsimbazafy J, Giacoma C, Gamba M. Call and be counted! Can we reliably estimate the number of callers in the indri's (Indri indri) song? PLoS One 2018; 13:e0201664. [PMID: 30075022 PMCID: PMC6075759 DOI: 10.1371/journal.pone.0201664] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/19/2018] [Indexed: 11/19/2022] Open
Abstract
Estimating the number of animals participating in a choral display may contribute reliable information on animal population estimates, particularly when environmental or behavioral factors restrict the possibility of visual surveys. Difficulties in providing a reliable estimate of the number of singers in a chorus are many (e.g., background noise masking, overlap). In this work, we contributed data on the vocal chorusing of the indri lemurs (Indri indri), which emit howling cries, known as songs, uttered by two to five individuals. We examined whether we could estimate the number of emitters in a chorus by screening the fundamental frequency in the spectrograms and the total duration of the songs, and the reliability of those methods when compared to the real chorus size. The spectrographic investigation appears to provide reliable information on the number of animals participating in the chorusing only when this number is limited to two or three singers. We also found that the Acoustic Complexity Index positively correlated with the real chorus size, showing that an automated analysis of the chorus may provide information about the number of singers. We can state that song duration shows a correlation with the number of emitters but also shows a remarkable variation that remains unexplained. The accuracy of the estimates can reflect the high variability in chorus size, which could be affected by group composition, season and context. In future research, a greater focus on analyzing frequency change occurring during these collective vocal displays should improve our ability to detect individuals and allow a finer tuning of the acoustic methods that may serve for monitoring chorusing mammals.
Collapse
Affiliation(s)
- Valeria Torti
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| | - Daria Valente
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| | - Chiara De Gregorio
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| | - Carlo Comazzi
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| | - Longondraza Miaretsoa
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| | - Jonah Ratsimbazafy
- Group d’Etude et de Recherche sur les Primates de Madagascar (GERP), Antananarivo, Madagascar
| | - Cristina Giacoma
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| | - Marco Gamba
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
| |
Collapse
|
3
|
Volodin IA, Matrosova VA, Frey R, Kozhevnikova JD, Isaeva IL, Volodina EV. Altai pika (Ochotona alpina) alarm calls: individual acoustic variation and the phenomenon of call-synchronous ear folding behavior. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2018; 105:40. [PMID: 29892847 DOI: 10.1007/s00114-018-1567-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/25/2018] [Accepted: 05/29/2018] [Indexed: 11/24/2022]
Abstract
Non-hibernating pikas collect winter food reserves and store them in hay piles. Individualization of alarm calls might allow discrimination between colony members and conspecifics trying to steal food items from a colony pile. We investigated vocal posture, vocal tract length, and individual acoustic variation of alarm calls, emitted by wild-living Altai pikas Ochotona alpina toward a researcher. Recording started when a pika started calling and lasted as long as possible. The alarm call series of 442 individual callers from different colonies consisted of discrete short (0.073-0.157 s), high-frequency (7.31-15.46 kHz), and frequency-modulated calls separated by irregular intervals. Analysis of 442 discrete calls, the second of each series, revealed that 44.34% calls lacked nonlinear phenomena, in 7.02% nonlinear phenomena covered less than half of call duration, and in 48.64% nonlinear phenomena covered more than half of call duration. Peak frequencies varied among individuals but always fitted one of three maxima corresponding to the vocal tract resonance frequencies (formants) calculated for an estimated 45-mm oral vocal tract. Discriminant analysis using variables of 8 calls per series of 36 different callers, each from a different colony, correctly assigned over 90% of the calls to individuals. Consequently, Altai pika alarm calls are individualistic and nonlinear phenomena might further increase this acoustic individualization. Additionally, video analysis revealed a call-synchronous, very fast (0.13-0.23 s) folding, depression, and subsequent re-expansion of the pinna confirming an earlier report of this behavior that apparently contributes to protecting the hearing apparatus from damage by the self-generated high-intensity alarm calls.
Collapse
Affiliation(s)
- Ilya A Volodin
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 12/1, Moscow, 119234, Russia. .,Scientific Research Department, Moscow Zoo, B. Gruzinskaya str., 1, Moscow, 123242, Russia.
| | - Vera A Matrosova
- Department of Structural and Functional Genomics, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str., 32, Moscow, 119991, Russia
| | - Roland Frey
- Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Str. 17, Berlin, Germany
| | - Julia D Kozhevnikova
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 12/1, Moscow, 119234, Russia
| | - Inna L Isaeva
- Scientific Research Department, Khakasskiy State Nature Reserve, Tsukanov str., 164, Abakan, 655017, Russia
| | - Elena V Volodina
- Scientific Research Department, Moscow Zoo, B. Gruzinskaya str., 1, Moscow, 123242, Russia
| |
Collapse
|
4
|
Gray SM, Montgomery RA, Millspaugh JJ, Hayward MW. Spatiotemporal variation in African lion roaring in relation to a dominance shift. J Mammal 2017. [DOI: 10.1093/jmammal/gyx020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
5
|
Déaux EC, Allen AP, Clarke JA, Charrier I. Concatenation of 'alert' and 'identity' segments in dingoes' alarm calls. Sci Rep 2016; 6:30556. [PMID: 27460289 PMCID: PMC4962046 DOI: 10.1038/srep30556] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 07/04/2016] [Indexed: 11/18/2022] Open
Abstract
Multicomponent signals can be formed by the uninterrupted concatenation of multiple call types. One such signal is found in dingoes, Canis familiaris dingo. This stereotyped, multicomponent ‘bark-howl’ vocalisation is formed by the concatenation of a noisy bark segment and a tonal howl segment. Both segments are structurally similar to bark and howl vocalisations produced independently in other contexts (e.g. intra- and inter-pack communication). Bark-howls are mainly uttered in response to human presence and were hypothesized to serve as alarm calls. We investigated the function of bark-howls and the respective roles of the bark and howl segments. We found that dingoes could discriminate between familiar and unfamiliar howl segments, after having only heard familiar howl vocalisations (i.e. different calls). We propose that howl segments could function as ‘identity signals’ and allow receivers to modulate their responses according to the caller’s characteristics. The bark segment increased receivers’ attention levels, providing support for earlier observational claims that barks have an ‘alerting’ function. Lastly, dingoes were more likely to display vigilance behaviours upon hearing bark-howl vocalisations, lending support to the alarm function hypothesis. Canid vocalisations, such as the dingo bark-howl, may provide a model system to investigate the selective pressures shaping complex communication systems.
Collapse
Affiliation(s)
- Eloïse C Déaux
- Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia
| | - Andrew P Allen
- Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia
| | - Jennifer A Clarke
- Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia
| | - Isabelle Charrier
- Université Paris Saclay, Université Paris-Sud, CNRS, UMR 9197, Institut des Neurosciences Paris-Saclay, Orsay, 91405, France
| |
Collapse
|
6
|
Déaux ÉC, Charrier I, Clarke JA. The bark, the howl and the bark-howl: Identity cues in dingoes' multicomponent calls. Behav Processes 2016; 129:94-100. [PMID: 27343622 DOI: 10.1016/j.beproc.2016.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/28/2016] [Accepted: 06/21/2016] [Indexed: 10/21/2022]
Abstract
Dingoes (genus Canis) produce a stereotyped bark-howl vocalisation, which is a unimodal complex signal formed by the concatenation of two call types (a bark and a howl). Bark-howls may function as alarm signals, although there has been no empirical investigation of this vocalisation's structure or function. We quantified the content and efficacy of the bark and howl segments separately and when combined, using 140 calls from 10 individuals. We found that both segments are individually distinctive, although howl segments are more accurately classified, suggesting a higher level of individuality. Furthermore, howls convey signature characteristics that are conserved across different contexts of production, and thus may act as 'identity signals'. The individual distinctiveness of full bark-howls increases above that of isolated segments, which may be a result of selection on improved signal discriminability. Propagation tests revealed that bark-howls are best described as medium-range signals, with both segments potentially allowing for individual discrimination up to 200m regardless of environmental conditions. We discuss our findings regarding the fitness benefits of encoding identity cues in a potential alarm call and propose additional hypotheses for the function(s) of bark and howl segments.
Collapse
Affiliation(s)
- Éloïse C Déaux
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
| | - Isabelle Charrier
- Université Paris-Saclay, Université Paris-Sud, CNRS, UMR 9197, Institut des Neurosciences Paris-Saclay, 91405, Orsay, France.
| | - Jennifer A Clarke
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
| |
Collapse
|