Applying mixture models to derive activity states of large herbivores from movement rates obtained using GPS telemetry
Norman Owen-Smith A D , Victoria Goodall B C and Paul Fatti BA School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa.
B School of Statistics and Actuarial Science, University of the Witwatersrand, Wits 2050, South Africa.
C South African Environmental Observation Network, Fynbos Node, Kirstenbosch, Newlands, 7735, South Africa.
D Corresponding author. Email: norman.owen-smith@wits.ac.za
Wildlife Research 39(5) 452-462 https://doi.org/10.1071/WR12062
Submitted: 24 January 2012 Accepted: 12 May 2012 Published: 7 June 2012
Abstract
Context: To interpret spatial utilisation distributions, there is a need to translate animal locations obtained from global positioning system (GPS) telemetry into the activities performed and, hence, benefits derived, from particular places and times of day. Derived activity patterns also reveal how animals cope in changing environmental conditions.
Aim: The aim of our research was to develop and test an objective, consistent and biologically faithful method for deriving activity states from movement rates between successive GPS locations.
Methods: The method entails fitting mixtures of component statistical distributions to the frequency distribution of hourly step displacements. Breakpoints indicating transitions between predominant movement modes were identified by fitting exponential segments. Breakpoints were incorporated as off-sets for gamma distributions, but not needed for log-normal distributions. This procedure was applied to movement data for three large grazing ungulates.
Key results: Models consistently distinguished four movement modes interpreted as representing resting, foraging, mixed movement and travelling activity. Breakpoints and parameter estimates were consistent among seasons and herds of each ungulate species. The exponential-segment model and both mixture models closely represented observed daily activity patterns. However, some adjustment of the derived time budgets was needed to be consistent with observations.
Key conclusions: Mixture models provide an objective, reliable and biologically meaningful procedure for assessing seasonal, annual and spatial variation in the activity patterns of large ungulates from GPS data.
Implications: The method can potentially be applied to other mobile foragers large enough to carry GPS collars.
References
Beekman, J. H., and Prins, H. H. T. (1989). Feeding strategies of sedentary large herbivores in East Africa, with emphasis on the African buffalo. African Journal of Ecology 27, 129–147.| Feeding strategies of sedentary large herbivores in East Africa, with emphasis on the African buffalo.Crossref | GoogleScholarGoogle Scholar |
Benhamou, S., and Cornelis, D. (2010). Incorporating movement behaviour and barriers to improve kernel home range space use estimates. The Journal of Wildlife Management 74, 1353–1360.
Bolker, B. M. (2008). ‘Ecological Models and Data in R.’ (Princeton University Press: Princeton, NJ.)
Börger, L., Dalziel, B. D., and Fryxell, J. M. (2008). Are there general mechanisms of animal home range behaviour? A review and prospects for future research. Ecology Letters 11, 637–650.
| Are there general mechanisms of animal home range behaviour? A review and prospects for future research.Crossref | GoogleScholarGoogle Scholar |
Bunnell, F. L., and Harestad, A. S. (1989). Activity budgets and body weight in mammals. How sloppy can mammals be? Current Mammalogy 2, 245–305.
Cagnacci, F., Boitani, L., Powell, R. A., and Boyce, M. S. (2010). Animal ecology meets GPS-based radiotelemetry: a perfect storm of opportunities and challenges. Philosophical Transactions of the Royal Society B 365, 2157–2162.
| Animal ecology meets GPS-based radiotelemetry: a perfect storm of opportunities and challenges.Crossref | GoogleScholarGoogle Scholar |
Cain, J. W., Owen-Smith, N., and Macandza, V. (2012). The costs of drinking: comparative water dependency of sable antelope and zebra. Journal of Zoology 286, 58–67.
| The costs of drinking: comparative water dependency of sable antelope and zebra.Crossref | GoogleScholarGoogle Scholar |
Everitt, B. S., and Hand, D. J. (1981). ‘Finite Mixture Distributions.’ (Chapman & Hall: London.)
Gillingham, M. P., Parker, K. L., and Hanley, T. A. (1997). Forage intake by black-tailed deer in a natural environment: bout dynamics. Canadian Journal of Zoology 75, 1118–1128.
| Forage intake by black-tailed deer in a natural environment: bout dynamics.Crossref | GoogleScholarGoogle Scholar |
Gogan, P. J. P. (1973). ‘Some Aspects of Nutrient Utilization by Burchell’s Zebra in the Serengeti-Mara region, East Africa.’ M.Sc. Thesis, Texas A&M University, College Station, TX.
Grimsdell, J. J. R., and Field, C. R. (1976). Grazing patterns of buffalos in the Rwenzori National Pard, Uganda. East African Wildlife Journal 14, 339–344.
Grobler, J. H. (1981). Feeding behaviour of sable in the Rhodes Matopos National Park, Zimbabwe. South African Journal of Zoology 16, 50–58.
Johnson, C. J., Parker, K. L., Heard, D. C., and Gillingham, M. P. (2002). Movement parameters of ungulates and scale-specific responses to the environment. Journal of Animal Ecology 71, 225–235.
| Movement parameters of ungulates and scale-specific responses to the environment.Crossref | GoogleScholarGoogle Scholar |
Klingel, H. (1967). Soziale Organisation und Verhalten feilebender Steppenzebras. Zeitschrift für Tierpsychologie 24, 580–624.
| Soziale Organisation und Verhalten feilebender Steppenzebras.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DyaF1czptFOrsg%3D%3D&md5=bdaaea9288b3167fe9b4edd6b1af1402CAS |
McLachlan, G., and Peel, D. (2000). ‘Finite Mixture Models.’ (John Wiley: New York.)
Neuhaus, P., and Ruckstuhl, K. E. (2002). The link between sexual dimorphism, activity budgets and group cohesion: the case of plains zebra. Canadian Journal of Zoology 80, 1437–1441.
| The link between sexual dimorphism, activity budgets and group cohesion: the case of plains zebra.Crossref | GoogleScholarGoogle Scholar |
Owen-Smith, N. (2002). ‘Adaptive Herbivore Ecology. From Resources to Populations in Variable Environments.’ (Cambridge University Press: Cambridge, UK.)
Owen-Smith, N., and Novellie, P. (1982). What should a clever ungulate eat? American Naturalist 119, 151–178.
Owen-Smith, N., Fryxell, J. M., and Merrill, E. H. (2010). Foraging theory upscaled: the behavioural ecology of herbivore movement. Philosophical Transactions of the Royal Society B 365, 2267–2278.
| Foraging theory upscaled: the behavioural ecology of herbivore movement.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC3crjt1Gjtw%3D%3D&md5=0c47719283a1dc280581451cf3119f6eCAS |
R Development Core Team (2010). ‘R: A Language and Environment for Statistical Computing.’ (R Foundation for Statistical Computing: Vienna.) Available at http://www.R-project.org/ [Verified 20 January 2012].
Ryan, S. J., and Jordaan, W. (2005). Activity patterns of African buffalo in the Lower Sabi region, Kruger National Park, South Africa. Koedoe 48, 117–124.
Sibly, R. M., Nott, H. M. R., and Fletcher, D. J. (1990). Splitting behaviour into bouts. Animal Behaviour 39, 63–69.
| Splitting behaviour into bouts.Crossref | GoogleScholarGoogle Scholar |
Sinclair, A. R. E. (1977). ‘The African Buffalo. A Study of Resource Limitation of Populations.’ (University of Chicago Press: Chicago, IL.)
Spalinger, S. E., and Hobbs, N. T. (1992). Mechanisms of foraging in mammalian herbivores: new model of functional response. American Naturalist 140, 325–348.
| Mechanisms of foraging in mammalian herbivores: new model of functional response.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD1Mzjt1KgtQ%3D%3D&md5=cea2c88a9e1928f87baef2ccfb74ba67CAS |
Turner, W. C., Jolles, A. E., and Owen-Smith, N. (2005). Alternating sexual segregation during the mating season by male African buffalo. Journal of Zoology 267, 291–299.
| Alternating sexual segregation during the mating season by male African buffalo.Crossref | GoogleScholarGoogle Scholar |
Twine, W. (2002). Feeding time budgets of selected African ruminant and non-ruminant grazers. African Journal of Ecology 40, 410–412.
| Feeding time budgets of selected African ruminant and non-ruminant grazers.Crossref | GoogleScholarGoogle Scholar |
Winterbach, H. E. K., and Bothma, JduP. (1998). Activity patterns of the Cape buffalo in the Willem Pretorius Game Reserve, Free State. South African Journal of Wildlife Research 28, 73–81.
Zucchini, W., and MacDonald, I. L. (2009). ‘Hidden Markov Models for Time Series – An Introduction Using R.’ (Chapman & Hall/CRC: Boca Raton, FL.)
