Female Songs of the Nonduetting Javan Gibbons (Hylobates moloch) Function for Territorial Defense
Duets in territorial, pair-living primates may function to maintain intragroup cohesion, promote intergroup avoidance, and assist in territorial and resource defense, as well as advertising and reinforcing pair bonds. Despite the absence of duetting in Javan gibbons (Hylobates moloch), recent playback experiments suggested that Javan gibbon songs also play a role in pair-bond advertisement as well as territorial and mate defense. However, playback experiments only assess motivations of the listener, which may not reflect the motivations of the caller. We conducted an observational study of naturally occurring female songs in two groups of Javan gibbons from July 2009 to March 2010 and from March to November 2011 in Gunung Halimun–Salak National Park, Indonesia. We investigated female singing rates in relation to singing location, daily path length, occurrence of intergroup encounters, feeding rate, allogrooming rate, and distance between pair mates. The two females produced 47 songs during 164 observation days. Females in the area of their home range that overlapped with neighboring groups sang more frequently than expected based on time spent in the area of overlap vs. the home range interior. Groups also had longer daily path lengths on days when females sang than on nonsinging days, and on days when they visited the area of overlap than on nonvisiting days. Our findings indicate that, like the duets of other pair-living territorial primates, female Javan gibbon songs function for territorial defense, but we found no support for other functions such as intergroup avoidance, resource defense, and pair-bond reinforcement.
KeywordsNonduetting gibbons Primate long-distance calls Ranging behavior Social monogamy Song functions
This project was conducted in collaboration with the Department of Natural Resource Conservation and Ecotourism at the Institut Pertanian Bogor (IPB). We thank the Indonesian Ministry of Research and Technology (RISTEK), the Indonesian Ministry of Forestry’s Department for the Protection and Conservation of Nature (PHKA), and the Gunung Halimun-Salak National Park (GHSNP) for granting us research permissions. We thank Rinekso Soekmadi, Agus Hikmat, Dones Rinaldi, Bambang Supriyanto, and GHSNP staff for their assistance and cooperation. We are grateful to Christophe Boesch, Catherine Crockford and Kurt Hammerschmidt for their advice on the discussion of this manuscript, to Roger Mundry and Colleen Stephens for their help with statistical analysis, and to Joanna Setchell and two anonymous reviewers for many helpful comments on the manuscript. Thanks to Sanha Kim for contributions to the establishment of the field site and advice on the progress of this study and the manuscript; Sunyoung Ahn for administrative support and coordination; and Aris, Nui, Sahri, Ami, and Jaya for assistance in the field. The authors declare that none of us have any conflict of interest in this research. This research was financially supported by the Amore Pacific Academic and Cultural Foundation (AACF), Ewha Womans University, National Institute of Ecology (NIE), German Academic Exchange Service (DAAD), the Max Planck Society (MPG), and Appalachian State University.
- Bartlett, T. Q. (2007). The Hylobatidae: Small apes of Asia. In C. J. Campbell, A. Fuentes, K. C. MacKinnon, & S. K. Bearder (Eds.), Primates in perspective (pp. 300–312). New York: Oxford University Press.Google Scholar
- Bartlett, T. Q. (2009a). Seasonal home range use and defendability in white-handed gibbons (Hylobates lar) in Khao Yai National Park, Thailand. In D. Whittaker & S. Lappan (Eds.), The gibbons: New perspectives on small ape socioecology and population biology (pp. 265–275). Developments in primatology: Progress and prospects. New York: Springer Science+Business media.Google Scholar
- Bartlett, T. Q. (2009b). Territoriality and intergroup encounters. In R. W. Sussmann & N. Vasey (Eds.), The gibbons of Khao Yai: Seasonal variation in behaviour and ecology (pp. 103–119). Upper Saddle River: Pearson Prentice Hall.Google Scholar
- Bates, D., Maechler, M., Bolker, B., & Walker, S. (2013). lme4: Linear mixed-effects models using Eigen and S4 classes. R package version 10–4. http://CRAN.R-project.org/package=lme4.
- Beyer, H.L. (2012). Geospatial modelling environment (v0.7.2.0). http://www.spatialecology.com/gme.
- Cheney, D. L. (1987). Interactions and relationships between groups. In B. B. Smuts, D. L. Cheney, R. M. Seyfarth, R. W. Wrangham, & T. T. Struhsaker (Eds.), Primate societies (pp. 267–281). Chicago: University of Chicago Press.Google Scholar
- Chivers, D. J., Anandam, M. V., Groves, C. P., Molur, S., Rawson, B. M., et al (2013). Family Hylobotidae (gibbons). In R. A. Mittermeier, A. B. Rylands, & D. E. Wilson (Eds.), Handbook of the mammals of the world (pp. 754–791). Barcelona: Lynx Edicions.Google Scholar
- Cohen, J., Cohen, P., West, S. G., & Aiken, L. S. (2003). Applied multiple regression/correlation analysis for the behavioral sciences. Mahwah: Lawrence Erlbaum.Google Scholar
- Ellefson, J. O. (1968). Territorial behavior in the common white-handed gibbon, Hylobates lar Linn. In P. C. Jay (Ed.), Primates: Studies in adaptation and variability (pp. 180–199). New York: Holt, Rinehart and Winston.Google Scholar
- ESRI (2011). ArcMap 10. Redlands: Environmental Systems Research Institute.Google Scholar
- Field, A. (2005). Discovering statistics using SPSS. London: SAGE.Google Scholar
- Fox, J., & Weisberg, S. (2011). An R companion to applied Rregression. Thousand Oaks: SAGE.Google Scholar
- Geissmann, T. (2000). Gibbon songs and human music from an evolutionary perspective. In N. L. Wallin, B. Merker, & S. Brown (Eds.), The origins of music (pp. 103–123). Cambridge: MIT Press.Google Scholar
- Gittins, S. P. (1984). Territorial advertisement and defence in gibbons. In H. Preuschoft, D. J. Chivers, W. Y. Brockelman, & N. Creel (Eds.), The lesser apes: Evolutionary and behavioural biology (pp. 420–424). Edinburgh: Edinburgh University Press.Google Scholar
- Hothorn, T., & Hornik, K. (2013). exactRankTests: Exact distributions for rank and permutation tests. R package version, 0.8–027. http://CRAN.R-project.org/package=exactRankTests.
- Kappeler, M. (1984). Vocal bouts and territorial maintenance in the moloch gibbon. In H. Preuschoft, D. J. Chivers, W. Y. Brockelman, & N. Creel (Eds.), The lesser apes: Evolutionary and behavioural biology (pp. 376–389). Edinburgh: Edinburgh University Press.Google Scholar
- Kinnaird, M. F., & O’Brien, T. G. (2005). Fast foods of the forest: The influence of figs on primates and hornbills across Wallace's line. In J. L. dew & J. P. Boubli (Eds.), Tropical fruits and frugivores: The search for strong interactors (pp. 155–184). Dordrecht, the Netherlands: Springer.Google Scholar
- Leighton, D. R. (1987). Gibbons: Territoriality and monogamy. In B. B. Smuts, D. L. Cheney, R. M. Seyfarth, R. W. Wrangham, & T. T. Struhsaker (Eds.), Primate societies (pp. 135–145). Chicago: University of Chicago Press.Google Scholar
- Malone, N., & Fuentes, A. (2009). The ecology and evolution of hylobatid communities: Causal and contextual factors underlying inter-and intraspecific variation. In S. Lappan & D. J. Whittaker (Eds.), The gibbons: New perspectives on small ape socioecology and population biology (pp. 241–264). Developments in primatology progress and prospects. New York: Springer Science+Business media.Google Scholar
- Pebesma, E. J., & Bivand, R. S. (2005). Classes and methods for spatial data in R. R News, 5, 9–13.Google Scholar
- Riley, E. P. (2005). The loud call of the Sulawesi Tonkean macaque, Macaca tonkeana. Tropical Biodiversity, 8, 199–209.Google Scholar