Quantifying the interactions between koalas in a high-density population during the breeding period
Darcy J. Watchorn
A B and Desley A. Whisson A
+ Author Affiliations
- Author Affiliations
A School of Life and Environmental Sciences, Centre for Integrative Ecology, Faculty of Science, Engineering and the Built Environment, Deakin University, Burwood Campus, 221 Burwood Highway, Burwood, Vic. 3125, Australia.
B Corresponding author. Email: dwatchorn@deakin.edu.au
Australian Mammalogy 42(1) 28-37 https://doi.org/10.1071/AM18027
Submitted: 11 August 2018 Accepted: 2 March 2019 Published: 14 May 2019
Abstract
A species’ social structure influences its patterns of gene flow and disease transmission. Knowledge of social structure therefore is critical for understanding conservation challenges and informing management strategies. We examined the social structure of 33 free-ranging koalas (Phascolarctos cinereus) in a high-density population (6.7 koalas per hectare) during the early and peak phase of the breeding period (August–December) at Cape Otway, Victoria. We used GPS and proximity loggers to quantify koala space use and interactions, and direct observations to determine behaviours associated with interactions. Our proximity loggers recorded 661 interactions (64% male–female, 28% male–male and 8% female–female). A peak in male–male interactions at the onset of the breeding period suggested that males may physically compete for mates at this time. Male–female interactions increased from the onset of the breeding period, and were mostly of short duration (median duration 5.5 min). From field observations of interactions, and the absence of pouch young in December, many of these interactions may have been unsuccessful copulation attempts. Space use and social network analyses revealed that most males had strong links (total interaction duration >30 min) with only one or two females, despite their spatial overlap and interactions with multiple females. Body mass did not influence a male’s mating success in terms of number of female mates. Our results contrast with those of a lower-density population in central eastern Queensland, suggesting that some aspects of koala social structure may be plastic relative to population density.
Additional keywords: population density, proximity logger, social network.
References
Allan, B. M., Arnould, J. P., Martin, J. K., and Ritchie, E. G. (2013). A cost-effective and informative method of GPS tracking wildlife. Wildlife Research 40, 345–348.| A cost-effective and informative method of GPS tracking wildlife.Crossref | GoogleScholarGoogle Scholar |
Aplin, L. M., Farine, D. R., Morand‐Ferron, J., Cole, E. F., Cockburn, A., and Sheldon, B. C. (2013). Individual personalities predict social behaviour in wild networks of great tits (Parus major). Ecology Letters 16, 1365–1372.
| Individual personalities predict social behaviour in wild networks of great tits (Parus major).Crossref | GoogleScholarGoogle Scholar | 24047530PubMed |
Bercovitch, F., Tobey, J., Andrus, C., and Doyle, L. (2006). Mating patterns and reproductive success in captive koalas (Phascolarctos cinereus). Journal of Zoology 270, 512–516.
| Mating patterns and reproductive success in captive koalas (Phascolarctos cinereus).Crossref | GoogleScholarGoogle Scholar |
Beyer, H. L. (2012). Geospatial Modelling Environment (Version 0.7.2.1). Available at: http://www.spatialecology.com/gme [accessed 10 August 2017].
Bureau of Meteorology (2015). Climate statistics for Australian locations. Bureau of Meteorology, Station ID 090015. Available at: http://www.bom.gov.au/climate/averages/tables/cw_090015.shtml [accessed 15 June 2018].
Carrick, F., and Wood, A. (1986). Use of antibiotics in koalas. In ‘Proceedings of the 12th Annual Conference of the Wildlife Disease Association, Australasian Section, Tamborine Mountain, Queensland, Australia, May 18–23 1986.’ pp. 18–23.
Caudron, A., Negro, S., Fowler, M., Boren, L., Poncin, P., Robertson, B., and Gemmell, N. (2009). Alternative mating tactics in the New Zealand fur seal (Arctocephalus forsteri): when non-territorial males are successful too. Australian Journal of Zoology 57, 409–421.
| Alternative mating tactics in the New Zealand fur seal (Arctocephalus forsteri): when non-territorial males are successful too.Crossref | GoogleScholarGoogle Scholar |
Charlton, B. D., Ellis, W. A., McKinnon, A. J., Brumm, J., Nilsson, K., and Fitch, W. T. (2011a). Perception of male caller identity in koalas (Phascolarctos cinereus): acoustic analysis and playback experiments. PLoS One 6, e20329.
| Perception of male caller identity in koalas (Phascolarctos cinereus): acoustic analysis and playback experiments.Crossref | GoogleScholarGoogle Scholar | 21887242PubMed |
Charlton, B. D., Ellis, W. A., McKinnon, A. J., Cowin, G. J., Brumm, J., Nilsson, K., and Fitch, W. T. (2011b). Cues to body size in the formant spacing of male koala (Phascolarctos cinereus) bellows: honesty in an exaggerated trait. The Journal of Experimental Biology 214, 3414–3422.
| Cues to body size in the formant spacing of male koala (Phascolarctos cinereus) bellows: honesty in an exaggerated trait.Crossref | GoogleScholarGoogle Scholar | 21957105PubMed |
Croft, D. P., James, R., and Krause, J. (2008). ‘Exploring Animal Social Networks.’ (Princeton University Press: Princeton, NJ.)
Csardi, G., and Nepusz, T. (2006). The igraph software package for complex network research. InterJournal Complex Systems 1695, 1–9.
DELWP (2017). Cape Otway koala management actions. Department of Environment, Land, Water and Planning. Available at: https://www.wildlife.vic.gov.au/our-wildlife/koalas/koalas-at-cape-otway [accessed 4 May 2018].
Ellis, W., Hale, P., and Carrick, F. (2002a). Breeding dynamics of koalas in open woodlands. Wildlife Research 29, 19–25.
| Breeding dynamics of koalas in open woodlands.Crossref | GoogleScholarGoogle Scholar |
Ellis, W., Melzer, A., Carrick, F., and Hasegawa, M. (2002b). Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland. Wildlife Research 29, 303–311.
| Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland.Crossref | GoogleScholarGoogle Scholar |
Ellis, W., Bercovitch, F., FitzGibbon, S., Roe, P., Wimmer, J., Melzer, A., and Wilson, R. (2011). Koala bellows and their association with the spatial dynamics of free-ranging koalas. Behavioral Ecology 22, 372–377.
| Koala bellows and their association with the spatial dynamics of free-ranging koalas.Crossref | GoogleScholarGoogle Scholar |
Ellis, W., Fitzgibbon, S., Pye, G., Whipple, B., Barth, B., Johnston, S., Seddon, J., Melzer, A., Higgins, D., and Bercovitch, F. (2015). The role of bioacoustic signals in koala sexual selection: insights from seasonal patterns of associations revealed with GPS-proximity units. PLoS One 10, e0130657.
| The role of bioacoustic signals in koala sexual selection: insights from seasonal patterns of associations revealed with GPS-proximity units.Crossref | GoogleScholarGoogle Scholar | 26154295PubMed |
Farine, D. R., Strandburg-Peshkin, A., Berger-Wolf, T., Ziebart, B., Brugere, I., Li, J., and Crofoot, M. C. (2016). Both nearest neighbours and long-term affiliates predict individual locations during collective movement in wild baboons. Scientific Reports 6, 27704.
| Both nearest neighbours and long-term affiliates predict individual locations during collective movement in wild baboons.Crossref | GoogleScholarGoogle Scholar | 27292778PubMed |
Feige, S., Nilsson, K., Phillips, C. J. C., and Johnston, S. D. (2007). Heterosexual and homosexual behaviour and vocalisations in captive female koalas (Phascolarctos cinereus). Applied Animal Behaviour Science 103, 131–145.
| Heterosexual and homosexual behaviour and vocalisations in captive female koalas (Phascolarctos cinereus).Crossref | GoogleScholarGoogle Scholar |
Fieberg, J., and Kochanny, C. O. (2005). Quantifying home-range overlap: the importance of the utilization distribution. Journal of Wildlife Management 69, 1346–1359.
| Quantifying home-range overlap: the importance of the utilization distribution.Crossref | GoogleScholarGoogle Scholar |
Freeman, L. C. (1979). Centrality in social networks. I: conceptual clarification. Social Networks 1, 215–239.
| Centrality in social networks. I: conceptual clarification.Crossref | GoogleScholarGoogle Scholar |
Gibson, K. N. (2010). Male mating tactics in spider monkeys: sneaking to compete. American Journal of Primatology 72, 794–804.
| Male mating tactics in spider monkeys: sneaking to compete.Crossref | GoogleScholarGoogle Scholar | 20653005PubMed |
Goldingay, R. L. (2015). A review of home-range studies on Australian terrestrial vertebrates: adequacy of studies, testing of hypotheses, and relevance to conservation and international studies. Australian Journal of Zoology 63, 136–146.
| A review of home-range studies on Australian terrestrial vertebrates: adequacy of studies, testing of hypotheses, and relevance to conservation and international studies.Crossref | GoogleScholarGoogle Scholar |
Hagens, S. V., Rendall, A. R., and Whisson, D. A. (2018). Passive acoustic surveys for predicting species’ distributions: Optimising detection probability. PLoS One 13, e0199396. , .
| Passive acoustic surveys for predicting species’ distributions: Optimising detection probability.Crossref | GoogleScholarGoogle Scholar |
Hamede, R. K., Bashford, J., McCallum, H., and Jones, M. (2009). Contact networks in a wild Tasmanian devil (Sarcophilus harrisii) population: using social network analysis to reveal seasonal variability in social behaviour and its implications for transmission of devil facial tumour disease. Ecology Letters 12, 1147–1157.
| Contact networks in a wild Tasmanian devil (Sarcophilus harrisii) population: using social network analysis to reveal seasonal variability in social behaviour and its implications for transmission of devil facial tumour disease.Crossref | GoogleScholarGoogle Scholar | 19694783PubMed |
Ji, W., White, P. C., and Clout, M. N. (2005). Contact rates between possums revealed by proximity data loggers. Journal of Applied Ecology 42, 595–604.
| Contact rates between possums revealed by proximity data loggers.Crossref | GoogleScholarGoogle Scholar |
Johnston, S., McGowan, M., O’Callaghan, P., Cox, R., and Nicolson, V. (2000). Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus). Journal of Reproduction and Fertility 120, 49–57.
| Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus).Crossref | GoogleScholarGoogle Scholar | 11006145PubMed |
Kasumovic, M. M., Bruce, M. J., Andrade, M. C. B., and Herberstein, M. E. (2008). Spatial and temporal demographic variation drives within-season fluctuations in sexual selection. Evolution 62, 2316–2325.
| Spatial and temporal demographic variation drives within-season fluctuations in sexual selection.Crossref | GoogleScholarGoogle Scholar | 18564373PubMed |
Knell, R. J. (2009). Population density and the evolution of male aggression. Journal of Zoology 278, 83–90.
| Population density and the evolution of male aggression.Crossref | GoogleScholarGoogle Scholar |
Kokko, H., and Rankin, D. J. (2006). Lonely hearts or sex in the city? Density-dependent effects in mating systems. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 361, 319–334.
| Lonely hearts or sex in the city? Density-dependent effects in mating systems.Crossref | GoogleScholarGoogle Scholar | 16612890PubMed |
Krause, J., James, R., Franks, D. W., and Croft, D. P. (2015). ‘Animal Social Networks.’ (Oxford University Press: USA.)
Krockenberger, A. (2003). Meeting the energy demands of reproduction in female koalas, Phascolarctos cinereus: evidence for energetic compensation. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 173, 531–540.
| Meeting the energy demands of reproduction in female koalas, Phascolarctos cinereus: evidence for energetic compensation.Crossref | GoogleScholarGoogle Scholar | 12827418PubMed |
Legione, A., Patterson, J., Whiteley, P., Amery-Gale, J., Lynch, M., Haynes, L., Gilkerson, J., Polkinghorne, A., Devlin, J., and Sansom, F. (2016). Identification of unusual Chlamydia pecorum genotypes in Victorian koalas (Phascolarctos cinereus) and clinical variables associated with infection. Journal of Medical Microbiology 65, 420–428.
| Identification of unusual Chlamydia pecorum genotypes in Victorian koalas (Phascolarctos cinereus) and clinical variables associated with infection.Crossref | GoogleScholarGoogle Scholar | 26932792PubMed |
Lusseau, D., Wilson, B., Hammond, P. S., Grellier, K., Durban, J. W., Parsons, K. M., Barton, T. R., and Thompson, P. M. (2006). Quantifying the influence of sociality on population structure in bottlenose dolphins. Journal of Animal Ecology 75, 14–24.
| Quantifying the influence of sociality on population structure in bottlenose dolphins.Crossref | GoogleScholarGoogle Scholar | 16903039PubMed |
Marsh, M. K., McLeod, S. R., Hutchings, M. R., and White, P. C. (2011). Use of proximity loggers and network analysis to quantify social interactions in free-ranging wild rabbit populations. Wildlife Research 38, 1–12.
| Use of proximity loggers and network analysis to quantify social interactions in free-ranging wild rabbit populations.Crossref | GoogleScholarGoogle Scholar |
Martin, R., and Handasyde, K. A. (1999). ‘The Koala: Natural History, Conservation and Management.’ (University of New South Wales Press: Sydney.)
McAlpine, C., Lunney, D., Melzer, A., Menkhorst, P., Phillips, S., Phalen, D., Ellis, W., Foley, W., Baxter, G., de Villiers, D., Kavanagh, R., Adams-Hosking, C., Todd, C., Whisson, D., Molsher, R., Walter, M., Lawler, I., and Close, R. (2015). Conserving koalas: a review of the contrasting regional trends, outlooks and policy challenges. Biological Conservation 192, 226–236.
| Conserving koalas: a review of the contrasting regional trends, outlooks and policy challenges.Crossref | GoogleScholarGoogle Scholar |
McLean, N. (2003). Ecology and management of overabundant koala (Phascolarctos cinereus) populations. Ph.D. Thesis, University of Melbourne.
McLean, N., and Handasyde, K. A. (2006). Sexual maturity, factors affecting the breeding season and breeding in consecutive seasons in populations of overabundant Victorian koalas (Phascolarctos cinereus). Australian Journal of Zoology 54, 385–392.
| Sexual maturity, factors affecting the breeding season and breeding in consecutive seasons in populations of overabundant Victorian koalas (Phascolarctos cinereus).Crossref | GoogleScholarGoogle Scholar |
Menkhorst, P. (2008). Hunted, marooned, re-introduced, contracepted: a history of koala management in Victoria. In ‘Too Close for Comfort: Contentious Issues in Human–Wildlife Encounters’. (Eds D. Lunney, A. Munn and W. Meikle.) pp. 73–92. (Royal Zoological Society of New South Wales: Sydney.)
Mitchell, P. (1990a). Social behaviour and communication of koalas. In ‘Biology of the Koala’. (Eds A. K. Lee, K. A. Handasyde, and G. D. Sanson.) pp. 151–170. (Surrey Beatty: Sydney.)
Mitchell, P. (1990b). The home ranges and social activity of koalas – a quantitative analysis. In ‘Biology of the Koala’. (Eds A. K. Lee, K. A. Handasyde, and G. D. Sanson.) pp. 171–187. (Surrey Beatty: Sydney.)
Parreira, B. R., and Chikhi, L. (2015). On some genetic consequences of social structure, mating systems, dispersal, and sampling. Proceedings of the National Academy of Sciences of the United States of America 112, E3318–E3326.
| On some genetic consequences of social structure, mating systems, dispersal, and sampling.Crossref | GoogleScholarGoogle Scholar | 26080393PubMed |
Pinter-Wollman, N., Hobson, E. A., Smith, J. E., Edelman, A. J., Shizuka, D., De Silva, S., Waters, J. S., Prager, S. D., Sasaki, T., Wittemyer, G., and Fewell, J. (2014). The dynamics of animal social networks: analytical, conceptual, and theoretical advances. Behavioral Ecology 25, 242–255.
| The dynamics of animal social networks: analytical, conceptual, and theoretical advances.Crossref | GoogleScholarGoogle Scholar |
Powell, R. (2000). Animal home ranges and territories and home range estimators. In ‘Research Techniques in Animal Ecology: Controversies and Consequences’. (Eds L. Boitani, and T. K. Fuller.) pp. 65–110. (Columbia University Press: New York.)
R Core Team (2017). R: a language and environment for statistical computing. Available at: http://www.R-project.org [accessed 10 August 2017].
Ryan, M. A., Whisson, D. A., Holland, G. J., and Arnould, J. P. (2013). Activity patterns of free-ranging koalas (Phascolarctos cinereus) revealed by accelerometry. PLoS One 8, e80366.
| Activity patterns of free-ranging koalas (Phascolarctos cinereus) revealed by accelerometry.Crossref | GoogleScholarGoogle Scholar | 24224050PubMed |
Schradin, C. (2013). Intraspecific variation in social organization by genetic variation, developmental plasticity, social flexibility or entirely extrinsic factors. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 368, 20120346.
| Intraspecific variation in social organization by genetic variation, developmental plasticity, social flexibility or entirely extrinsic factors.Crossref | GoogleScholarGoogle Scholar | 23569294PubMed |
Sikes, R.S., the Animal Care and Use Committee of the American Society of Mammalogists (2016). Guidelines of the American Society of Mammalogists for the use of wild mammals in research and education. Journal of Mammalogy 97, 663–688.
| Guidelines of the American Society of Mammalogists for the use of wild mammals in research and education.Crossref | GoogleScholarGoogle Scholar | 29692469PubMed |
Silk, M. J., and Fisher, D. N. (2017). Understanding animal social structure: exponential random graph models in animal behaviour research. Animal Behaviour 132, 137–146.
| Understanding animal social structure: exponential random graph models in animal behaviour research.Crossref | GoogleScholarGoogle Scholar |
Silk, M. J., Croft, D. P., Delahay, R. J., Hodgson, D. J., Weber, N., Boots, M., and McDonald, R. A. (2017). The application of statistical network models in disease research. Methods in Ecology and Evolution 8, 1026–1041.
| The application of statistical network models in disease research.Crossref | GoogleScholarGoogle Scholar |
Smith, M. (1980). Behaviour of the koala, Phascolarctos cinereus (Goldfuss), in captivity. V. Sexual behaviour. Wildlife Research 7, 41–51.
| Behaviour of the koala, Phascolarctos cinereus (Goldfuss), in captivity. V. Sexual behaviour.Crossref | GoogleScholarGoogle Scholar |
Sueur, C., and Mery, F. (2017). Editorial: Social interaction in animals: linking experimental approach and social network analysis. Frontiers in Psychology 8
Walter, W. D., Onorato, D. P., and Fischer, J. W. (2015). Is there a single best estimator? Selection of home range estimators using area-under-the-curve. Movement Ecology 3, 10.
| Is there a single best estimator? Selection of home range estimators using area-under-the-curve.Crossref | GoogleScholarGoogle Scholar | 25973204PubMed |
Whisson, D. A., and Carlyon, K. (2010). Temporal variation in reproductive characteristics of an introduced and abundant island population of koalas. Journal of Mammalogy 91, 1160–1167.
| Temporal variation in reproductive characteristics of an introduced and abundant island population of koalas.Crossref | GoogleScholarGoogle Scholar |
Whisson, D. A., Dixon, V., Taylor, M. L., and Melzer, A. (2016). Failure to respond to food resource decline has catastrophic consequences for koalas in a high-density population in southern Australia. PLoS One 11, e0144348.
| Failure to respond to food resource decline has catastrophic consequences for koalas in a high-density population in southern Australia.Crossref | GoogleScholarGoogle Scholar | 26735846PubMed |
Whitehead, H. (2008). ‘Analyzing Animal Societies: Quantitative Methods for Vertebrate Social Analysis.’ (University of Chicago Press: Chicago.)
