Abstract
For species that cannot seek cover to escape predators, aggregation becomes an important strategy to reduce predation risk. However, aggregation may not be entirely beneficial because aggregated animals may compete for access to limited resources and might even attract predators. Available evidence suggests that foraging competition influences time allocation in large-bodied macropodid marsupials, but previous studies have focused primarily on species in areas with protective cover. We studied red kangaroos, a species often found in open country without noticeable cover, to determine whether they experienced a net benefit by aggregation. Red kangaroos varied their time allocation as a function of group size and, importantly, more variation in time allocation to vigilance and foraging was explained by non-linear models than by linear models. This suggests red kangaroos directly translated the reduction of predation risk brought about by aggregation into greater time foraging and less time engaged in vigilance. We infer that red kangaroos received a net benefit by aggregation. Social species living in the open may be generally expected to rely on others to help manage predation risk.
Similar content being viewed by others
References
Alexander RD (1974) The evolution of social behavior. Annu Rev Ecol Syst 5:325–383
Beauchamp G (1998) The effect of group size on mean food intake rate in birds. Biol Rev 73:449–472
Bednekoff PA, Lima SL (1998) Randomness, chaos and confusion in the study of antipredator vigilance. Trends Ecol Evol 13:284–287
Bertram BCR (1980) Vigilance and group size in ostriches. Anim Behav 28:278–286
Blumstein DT (1998) Quantifying predation risk for refuging animals: a case study with golden marmots. Ethology 104:501–516
Blumstein DT, Daniel JC (2002) Isolation from mammalian predators differentially affects two congeners. Behav Ecol 13:657–663
Blumstein DT, Evans CS, Daniel JC (1999) An experimental study of behavioural group size effects in tammar wallabies (Macropus eugenii). Anim Behav 58:351–360
Blumstein DT, Evans CS, Daniel JC (2000) JWatcher 0.9. An introductory user's guide. http://galliform.psy.mq.edu.au/jwatcher/ and http://www.jwatcher.ucla.edu
Blumstein DT, Daniel JC, Evans CS (2001a) Yellow-footed rock-wallaby (Petrogale xanthopus) group size effects reflect a trade-off. Ethology 107:655–664
Blumstein DT, Daniel JC, McLean IG (2001b) Group size effects in quokkas. Aust J Zool 49:641–649
Blumstein DT, Daniel JC, Ardron JG, Evans CS (2002) Does feeding competition influence tammar wallaby time allocation? Ethology 108:937–945
Caraco T, Martindale S, Pulliam HR (1980) Avian time budgets and distance to cover. Auk 97:872–875
Catterall CP, Elgar MA, Kikkawa J (1992) Vigilance does not covary with group size in an island population of silvereyes (Zosterops lateralis). Behav Ecol 3:207–210
Clark CW, Mangel M (1986) The evolutionary advantages of group foraging. Theor Popul Biol 30:45–79
Colagross AML, Cockburn A (1993) Vigilance and grouping in the eastern grey kangaroo, Macropus giganteus. Aust J Zool 41:325–334
Coulson G (1996) Anti-predator behaviour in marsupials. In: Croft DB, Gansloßer U (eds) Comparison of marsupial and placental behaviour. Filander, Fürth, Germany, pp 158–186
Coulson G (1999) Monospecific and heterospecific grouping and feeding behavior in grey kangaroos and red-necked wallabies. J Mamm 80:270–282
Dawson TJ (1995) Kangaroos: the biology of the largest marsupial. University of New South Wales Press, Sydney
Dill LM (1990) Distance-to-cover and the escape decisions of an African cichlid fish, Melanochromis chipokae. Environ Biol Fish 27:147–152
Elgar MA (1989) Predator vigilance and group size in mammals and birds: a critical review of the empirical evidence. Biol Rev 64:13–33
Grand TC, Dill LM (1999) The effect of group size on the foraging behaviour of juvenile coho salmon: reduction of predation risk or increased competition? Anim Behav 58:443–451
Hamilton WD (1971) Geometry for the selfish herd. J Theor Biol 31:295–311
Hamilton WJ III, Watt KEF (1970) Refuging. Annu Rev Ecol Syst 1:263–286
Heard DC (1992) The effect of wolf predation and snow cover on musk-ox group size. Am Nat 139:190–204
Jarman PJ (1987) Group size and activity in eastern grey kangaroos. Anim Behav 35:1044–1050
Jarman PJ, Coulson G (1989) Dynamics and adaptiveness of grouping in macropods. In: Grigg G, Jarman P, Hume I (eds) Kangaroos, wallabies and rat-kangaroos, vol 2. Surrey Beatty, Chipping Norton, New South Wales, pp 527–547
Kenward RE (1978) Hawks and doves: factors affecting success and selection in goshawk attacks on woodpigeons. J Anim Ecol 47:449–460
Kotler BP (1984) Risk of predation and the structure of desert rodent communities. Ecology 65:689–701
Lazarus J (1979) The early warning function of flocking in birds: an experimental study with captive quelea. Anim Behav 27:855–865
Lima SL, Dill LM (1990) Behavioral decisions made under the risk of predation: a review and prospectus. Can J Zool 68:619–640
Lima SL, Zollner PA, Bednekoff PA (1999) Predation, scramble competition, and the vigilance group size effect in dark-eyed juncos (Junco hyemalis). Behav Ecol Sociobiol 46:110–116
Low BS (1979) The predictability of rain and the foraging patterns of the red kangaroo (Megaleia rufa) in central Australia. J Arid Environ 2:61–76
Newsome A (1995) Red kangaroo. In: Strahan R (ed) The mammals of Australia. Reed Books, Chatswood, New South Wales, pp 353–355
Payne AL, Jarman PJ (1999) Macropod studies at Wallaby Creek X. Responses of eastern grey kangaroos to cattle. Wildl Res 26:215–225
Pople AR, Grigg GC, Cairns SC, Beard LA, Alexander P (2000) Trends in the numbers of red kangaroos and emus on either side of the South Australian dingo fence: evidence for predator regulation? Wildl Res 27:269–276
Powell GVN (1974) Experimental analysis of the social value of flocking by starlings (Sturnus vulgaris) in relation to predation and foraging. Anim Behav 22:501–505
Pulliam HR (1973) On the advantages of flocking. J Theor Biol 38:419–422
Quenette P-Y (1990) Functions of vigilance behaviour in mammals: a review. Acta Oecol 11:801–818
Sharpe PB, Van Horne B (1998) Influence of habitat on behavior of Townsend's ground squirrels (Spermophilus townsendii). J Mamm 79:906–918
SPSS Inc. (2000) SPSS-10 for the Macintosh. SPSS Inc., Chicago
Suhonen J (1993) Predation risk influences the use of foraging sites by tits. Ecology 74:1197–1203
Vine I (1971) Risk of visual detection and pursuit by a predator and the selective advantage of flocking behaviour. J Theor Biol 30:405–422
Wahungu GM, Catterall CP, Olsen MF (2001) Predator avoidance, feeding and habitat use in the red-necked pademelon, Thylogale thetis, at rainforest edges. Aust J Zool 49:45–58
Acknowledgements
We thank David Croft and the staff at Fowlers Gap for making our stay both productive and enjoyable. Support for this project came from grants to DTB from the University of California Los Angeles, and from the Australian Cooperative Grants Programme (via The Marsupial CRC). Research protocols were approved by the Macquarie University Animal Care Committee (#99018) and research complied with current Australian law.
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by K. Kotrschal
Rights and permissions
About this article
Cite this article
Blumstein, D.T., Daniel, J.C. Red kangaroos (Macropus rufus) receive an antipredator benefit from aggregation. acta ethol 5, 95–99 (2003). https://doi.org/10.1007/s10211-002-0070-5
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10211-002-0070-5