acta ethologica

, Volume 18, Issue 2, pp 101–110 | Cite as

Fission-fusion group dynamics in reindeer reveal an increase of cohesiveness at the beginning of the peak rut

  • Guillaume Body
  • Robert B. WeladjiEmail author
  • Øystein Holand
  • Mauri Nieminen
Original Paper


Knowledge of the processes of group formation is important to understand the evolution of animal societies. Ungulates typically aggregate during the breeding season. According to the self-organization theory, proximal processes such as mating tactics should explain variation in average group size through their influences on group dynamics. Here, we tested whether variation of the fusion rate or fission rate led to an increase of average group size at the beginning of the peak rut. We followed the movement of marked animals within an enclosed herd of reindeer Rangifer tarandus during two breeding seasons (2009 and 2011). We used synchronized GPS collars that fixed the animals’ position every hour (2009) and every 15 min (2011). Group dynamics occurred in three steps as follows: (1) a continuous aggregation of groups, (2) a continuous departure of single females from these groups, and (3) the aggregation of these solitary females to form new groups. We attributed the increase in average group size mainly to a decrease in the number of groups due to a decrease in the group and individual splitting propensities, rather than to an increase of their merging propensities. A decrease in the splitting propensity at the beginning of the peak rut may be due to males herding females, female mate choice, or female harassment avoidance. Further research on fission-fusion group dynamics should calculate merging and splitting propensities by controlling for variables such as group size, group density, or habitat characteristics.


Caribou Global positioning system Harem Mating Sexual selection Sociality 



The authors thank Jukka Siitari of the Finnish Game and Fisheries Research Station for the management of GPS collars data, and Mika Tervonen of the Finnish Reindeer Herder’s Association for the management of reindeers in Finland. We thank Sacha Engelhardt, Natalka Melnycky, and Hallvard Gjøstein who helped with data collection and Guillaume Larocque from the Quebec Center for Biodiversity Sciences for help with the statistics. We thank two anonymous reviewers for their helpful comments on an earlier version of this manuscript. We also acknowledge the financial support of the Natural Sciences and Engineering Research Council of Canada (RBW) and the Research Council of Norway (ØH).

Supplementary material

10211_2014_190_MOESM1_ESM.docx (253 kb)
ESM 1 (DOCX 253 kb)

(AVI 14790 kb)


(AVI 13098 kb)


  1. Aung M, Mcshea WJ, Htung S, Than A, Soe TM, Wemmer C (2001) Ecology and social organization of a tropical deer (Cervus eldi thamin). Am Soc Mammal 82:836–847CrossRefGoogle Scholar
  2. Aureli F, Schaffner CM, Boesch C, Bearder SK, Call J, Chapman CA, Connor R, Di Fiore A, Dunbar RIM, Henzi SP, Holekamp KE, Korstjens AH, Layton R, Lee PC, Lehmann J, Manson JH, Ramos-Fernández G, Strier KB, van Schaik CP (2008) Fission-fusion dynamics: new research frameworks. Curr Anthropol 49:627–654CrossRefGoogle Scholar
  3. Aureli F, Schaffner CM, Asensio N, Lusseau D (2012) What is a subgroup? How socioecological factors influence interindividual distance. Behav Ecol 23:1308–1315CrossRefGoogle Scholar
  4. Baddeley A (2010) Analysing spatial point patterns in R. :version 4.1
  5. Baddeley A, Gill RD (1997) Kaplan-Meier estimators of distance distributions for spatial point processes. Ann Stat 25:263–292CrossRefGoogle Scholar
  6. Barrette C (1991) The size of axis deer fluid groups in Wilpattu national park, Sri Lanka. Mammalia 55:207–220CrossRefGoogle Scholar
  7. Beauchamp G (2011) Functional relationship between group size and population density in Northwest Atlantic seabirds. Mar Ecol Prog Ser 435:225–233CrossRefGoogle Scholar
  8. Bercovitch FB, Berry PSM (2010) Ecological determinants of herd size in the Thornicroft’s giraffe of Zambia. Afr J Ecol 48:962–971CrossRefGoogle Scholar
  9. Bercovitch FB, Berry PSM (2012) Herd composition, kinship and fission-fusion social dynamics among wild giraffe. Afr J Ecol 51:206–216CrossRefGoogle Scholar
  10. Borkowski JJ, Furubayashi K (1998) Seasonal and diel variation in group size among Japanese sika deer in different habitats. J Zool (Lond) 245:29–34CrossRefGoogle Scholar
  11. Bro-Jørgensen J (2011) Intra- and intersexual conflicts and cooperation in the evolution of mating strategies: lessons learnt from ungulates. Evol Biol 38:28–41CrossRefGoogle Scholar
  12. Byers JA, Moodie JD, Hall N (1994) Pronghorn females choose vigorous mates. Anim Behav 47:33–43CrossRefGoogle Scholar
  13. Carter AJ, Pays O, Goldizen AW (2009) Individual variation in the relationship between vigilance and group size in eastern grey kangaroos. Behav Ecol Sociobiol 64:237–245CrossRefGoogle Scholar
  14. Caughley G (1964) Social organization and daily activity of the red kangaroo and the grey kangaroo. Am Soc Mammal 45:429–436CrossRefGoogle Scholar
  15. Clutton-Brock TH, McAuliffe K (2009) Female mate choice in mammals. Q Rev Biol 84:3–27CrossRefPubMedGoogle Scholar
  16. Clutton-Brock TH, Guinness F, Albon SD (1982) Red deer. Behavior and ecology of two sexes. Edinburgh University Press, EdinburghGoogle Scholar
  17. Clutton-Brock TH, Price OF, MacColl ADC (1992) Mate retention, harassment, and the evolution of ungulate leks. Behav Ecol 3:234–242CrossRefGoogle Scholar
  18. Couzin ID (2006) Behavioral ecology: social organization in fission-fusion societies. Curr Biol 16:169–171CrossRefGoogle Scholar
  19. Couzin ID, Krause J (2003) Self-organization and collective behavior in vertebrates. Adv Study Behav 32:1–75Google Scholar
  20. Couzin ID, Laidre ME (2009) Fission-fusion populations. Curr Biol 19:633–635CrossRefGoogle Scholar
  21. Crawley MJ (2007) The R book. John Wiley & Sons Ltd., Chichester, UKGoogle Scholar
  22. Croft DP, James R, Krause J (2008) Exploring animal social networks. Princeton University Press, PrincetonCrossRefGoogle Scholar
  23. Danchin E, Giraldeau L-A, Cézilly F (2008) Behavioural ecology. Oxford University Press, OxfordGoogle Scholar
  24. de Jong K, Forsgren E, Sandvik H, Amundsen T (2012) Measuring mating competition correctly: available evidence supports operational sex ratio theory. Behav Ecol 23:1170–1177CrossRefGoogle Scholar
  25. Djaković N, Holand Ø, Hovland AL, Røed KH, Weladji RB, Fjeldstad E, Nieminen M (2012) Association patterns and kinship in female reindeer (Rangifer tarandus) during rut. Acta Ethol 15:165–171CrossRefGoogle Scholar
  26. Emlen ST, Oring LW (1977) Ecology, sexual selection, and the evolution of mating systems. Science 197:215–223CrossRefPubMedGoogle Scholar
  27. Fishlock V, Lee PC (2013) Forest elephants: fission–fusion and social arenas. Anim Behav 85:357–363CrossRefGoogle Scholar
  28. Focardi S, Pecchioli E (2005) Social cohesion and foraging decrease with group size in fallow deer (Dama dama). Behav Ecol Sociobiol 59:84–91CrossRefGoogle Scholar
  29. Fortin D, Fortin M-E, Beyer HL, Duchesne T, Courant S, Dancose K (2009) Group-size-mediated habitat selection and group fusion-fission dynamics of bison under predation risk. Ecology 90:2480–2490CrossRefPubMedGoogle Scholar
  30. Gerard J-F, Bideau E, Maublanc M-L, Loisel P, Marchal C (2002) Herd size in large herbivores: encoded in the individual or emergent? Biol Bull 202:275–282CrossRefPubMedGoogle Scholar
  31. Gower CN, Garrott RA, White PJ, Cherry S, Yoccoz NG (2009) Elk group size and wolf predation: a flexible strategy when faced with variable risk. In: Garrott RA, White PJ, Watson FGR (eds) The ecology of large mammals in central Yellowstone, sixteen years of integrated field studies. Terrestria. Academic Press, New York, p 401:422Google Scholar
  32. Haydon DT, Morales JM, Yott A, Jenkins DA, Rosatte R, Fryxell JM (2008) Socially informed random walks: incorporating group dynamics into models of population spread and growth. Proc R Soc Lond 275:1101–1109CrossRefGoogle Scholar
  33. Jarman P (1974) The social organisation of antelope in relation to their ecology. Behaviour 48:215–267CrossRefGoogle Scholar
  34. Jedrzejewski W, Spaedtke H, Kamler JF, Jedrzejewska B, Stenkewitz U (2006) Group size dynamics of red deer in Białowieza Primeval Forest, Poland. J Wildl Manag 70:1054–1059CrossRefGoogle Scholar
  35. Johnson CN (1983) Variations in group size and composition in red and western grey kangaroos, Macropus rufus (Desmarest) and M. fuliginosus (Desmarest). Aust Wildl Res 10:25–31CrossRefGoogle Scholar
  36. Juanico DEO (2009) Herding tendency as an aggregating factor in a binary mixture of social entities. Ecol Model 220:3521–3526CrossRefGoogle Scholar
  37. King AJ, Wilson AM, Wilshin SD, Lowe JC, Haddadi H, Hailes S, Morton AJ (2012) Selfish-herd behaviour of sheep under threat. Curr Biol 22:561–562CrossRefGoogle Scholar
  38. Kojola I (1986) Rutting behaviour in an enclosured group of wild forest reindeer. Rangifer 1:173–179CrossRefGoogle Scholar
  39. Krause J, Krause S, Arlinghaus R, Psorakis I, Roberts S, Rutz C (2013) Reality mining of animal social systems. Trends Ecol Evol 28:541–551CrossRefPubMedGoogle Scholar
  40. L’Italien L, Weladji RB, Holand Ø, Røed KH, Nieminen M, Côté SD (2012) Mating group size and stability in reindeer Rangifer tarandus: the effects of male characteristics, sex ratio and male age structure. Ethology 118:783–792CrossRefGoogle Scholar
  41. Marshall HH, Carter AJ, Rowcliffe JM, Cowlishaw G (2012) Linking social foraging behaviour with individual time budgets and emergent group-level phenomena. Anim Behav 84:1295–1305CrossRefGoogle Scholar
  42. Mysterud A, Røed KH, Holand Ø, Yoccoz NG, Nieminen M (2009) Age-related gestation length adjustment in a large iteroparous mammal at northern latitude. J Anim Ecol 78:1002–1006CrossRefPubMedGoogle Scholar
  43. Pays O, Benhamou S, Helder R, Gerard J-F (2007) The dynamics of group formation in large mammalian herbivores: an analysis in the European roe deer. Anim Behav 74:1429–1441CrossRefGoogle Scholar
  44. Pays O, Fortin D, Gassani J, Duchesne J (2012) Group dynamics and landscape features constrain the exploration of herds in fusion-fission societies: the case of European roe deer. PLoS ONE 7:e34678CrossRefPubMedCentralPubMedGoogle Scholar
  45. Pépin D, Gerard J-F (2008) Group dynamics and local population density dependence of group size in the Pyrenean chamois, Rupicapra pyrenaica. Anim Behav 75:361–369CrossRefGoogle Scholar
  46. Proffitt KM, Gude JA, Shamhart J, King F (2012) Variations in elk aggregation patterns across a range of elk population sizes at Wall Creek, Montana. J Wildl Manag 76:847–856CrossRefGoogle Scholar
  47. Reimers E, Røed KH, Colman JE (2012) Persistence of vigilance and flight response behaviour in wild reindeer with varying domestic ancestry. J Evol Biol 25:1543–1554CrossRefPubMedGoogle Scholar
  48. Ripley BD (1988) Statistical inference for spatial processes. Cambridge University Press, New YorkCrossRefGoogle Scholar
  49. Sueur C, King AJ, Conradt L, Kerth G, Lusseau D, Mettke-Hofmann C, Schaffner CM, Williams L, Zinner D, Aureli F (2011) Collective decision-making and fission-fusion dynamics: a conceptual framework. Oikos 120:1608–1617CrossRefGoogle Scholar
  50. Tennenhouse EM, Weladji RB, Holand Ø, Røed KH, Nieminen M (2011) Mating group composition influences somatic costs and activity in rutting dominant male reindeer (Rangifer tarandus). Behav Ecol Sociobiol 65:287–295CrossRefGoogle Scholar
  51. Tennenhouse EM, Weladji RB, Holand Ø, Nieminen M (2012) Timing of reproductive effort differs between young and old dominant male reindeer. Ann Zool Fennici 49:152–160CrossRefGoogle Scholar
  52. Wade MJ, Shuster SM (2004) Sexual selection: harem size and the variance in male reproductive success. Am Nat 164:E83–E89CrossRefPubMedGoogle Scholar
  53. White PJ, Gower CN, Davis TL, Sheldon JW, White JR (2012a) Group dynamics of Yellowstone pronghorn. J Mammal 93:1129–1138CrossRefGoogle Scholar
  54. White PJ, Proffitt KM, Lemke TO (2012b) Changes in elk distribution and group sizes after wolf restoration. Am Midl Nat 167:174–187CrossRefGoogle Scholar
  55. Wiley RH, Poston J (1996) Indirect mate choice, competition for mates, and coevolution of the sexes. Evolution 50:1371–1381CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg and ISPA 2014

Authors and Affiliations

  • Guillaume Body
    • 1
  • Robert B. Weladji
    • 1
    Email author
  • Øystein Holand
    • 2
  • Mauri Nieminen
    • 3
  1. 1.Department of BiologyConcordia UniversityMontrealCanada
  2. 2.Department of Animal and Aquacultural SciencesNorwegian University of Life SciencesAasNorway
  3. 3.Finnish Game and Fisheries Research InstituteReindeer Research StationKaamanenFinland

Personalised recommendations