Summary
Annual seed consumption by a small mammal community in the semi-arid Karoo, South Africa, was calculated using population, biomass and dietary estimates and published estimates of field metabolic rate. The community comprised a macroscelid elephant shrew Macroscelides proboscideus, and two rodents Gerbillurus paeba and Desmodillus auricularis. Only G. paeba consumed seed during the study, and then in low amounts (annual mean = 0.4% of diet, insects = 53%, herbage = 47%), with M. proboscideus and D. auriocularis consuming mainly insects (88%) and herbage (90%), respectively. Energy requirements for the G. paeba population averaged 568 kJ ha−1 day−1. Total seed consumption was estimated to be ≈ 140 g ha−1, or 155 000 seeds ha−1 which represents ≈0.5% of the annual seed production for this site. These levels of granivory by small mammals are significantly lower than those recorded for North American deserts, and raises the question as to why granivory varies between these systems. These findings also refute the hypothesis that as a result of the harshness and similarity of physical conditions in deserts, the properties of desert communities are convergent.
Similar content being viewed by others
References
Boyer DC (1987) Effect of rodents on plant recruitment and production in the dune area of the Namib Desert. M.Sc. thesis, Univ. Natal, Pietermaritzburg, S. Africa
Brown JH, Ojeda RA (1987) Granivory: patterns and processes, and consequences of seed consumption on two continents. Rev Chil Hist Nat 60:337–349
Brown JH, Davidson DW, Munger JC, Inouye RS (1986) Experimental community ecology: the desert granivore system. In: Diamond J, Case TJ (eds) Community Ecology, Harper and Rowe, New York, pp 41–61
Chew RM, Chew AE (1970) Energy relationships of the mammals of a desert shurb (Larrea tridentata) community. Ecol Monogr 40:1–21
Churchfield S (1985) Diets of two syntopic small mammals in the Inyange National Park, Zimbabwe. S Afr J Zool 20:65–67
Drodz A (1975) Feeding and nutrition. In: Grodzinski W (ed) Methods of ecological bio-energetics. (IBP Handbook no. 24) pp 325–357
Ellis F, Lambrecht JJN (1986) Soils. In: Cowling RM, Roux PW, Pieterse AJH (eds) The Karoo Biome: a preliminary synthesis. Part 1 — Physical Environments. S Afr Natl Sci Progm Rep 124:18–38
French NR, Maza BG, Hill HO, Aschwanden AP, Kaaz HW (1974) A population study of irradiated desert rodents. Zool Monogr 44:45–72
Hansson L (1970) Methods of morphological diet micro-analysis in rodents. Oikos 21:255–266
Janzen DH (1971) Seed predation by animals. Annu Rev Ecol Syst 2:465–492
Kerley GIH (1989) Diet of small mammals from the Karoo, South Africa. S Afr J Wildl Res 19:67–72
Kerley GIH (1990) Small mammals as granivores in the Karoo. Ph.D. thesis, Univ Port Elizabeth, S Africa
Kerley GIH (1991) Seed removal by rodents, birds and ants in the semi-arid Karoo, South Africa. J Arid Environ 20:63–69
Kerley GIH (1992) Trophic status of small mammals in the semi-arid Karoo, South Africa. J Zool, Lond 226 (in press)
Kerley GIH, Erasmus T (1991) What do mice select for in seeds? Oecologia 86:261–267
Kerley GIH, Erasmus T (in press) Small mammal communities in the semi-arid Karoo, South Africa: biomass and energy requirements. J Arid Environ
Kerley GIH, Knight MH, Erasmus T (1990) Small mammal microhabitat use and diet in the southern Kalahari, South Africa. S Afr J Wildl Res 20:123–126
Korn H (1987) Densities and biomasses of non-fossorial southern African rodents during the dry season. Oecologia 72:410–413
Krebs CJ (1966) Demographic changes in fluctuating populations of Microtus californicus. Ecol Monogr 36:239–273
Milton SJ, Dean WRJ (1990) Seed production in rangelands of the Karoo. S Afr J Sci 86:231–233
Milton SJ, Dean WRJ, Kerley GIH (1991) Tierberg Karoo Research Centre: history, physical environment, flora and fauna. Trans Roy Soc S Afr 48: in press
Morton SR (1985) Granivory in arid regions: comparison of Australia with north and south America. Ecology 66:1859–1866
Nagy KA (1987) Field metabolic rate and food requirement scaling in mammals and birds. Ecol Monogr 57:111–128
Nel JAJ (1987) Habitat heterogeneity and changes in small mammal community structure and resource utilization in the southern Kalahari. Bull Carnegie Mus Nat Hist 6:118–132
Nelson JF, Chew RM (1977) Factors affecting seed reserves in the soil of a Mojave desert ecosystem, Rock Valley, Nye County, Nevada. Am Midl Nat 97:300–320
Orians GH, Solbrig OT (1977) An evolutionary approach to ecosystems. In: Orians GH, Solbrig OT (eds) Convergent evolution in warm deserts. US/IBP Series 3, pp 1–12
Parmenter RR, MacMahon JA, Vander Wall SB (1984) The measurement of granivory by desert rodents, birds and ants: a comparison of an energetics approach and a seed dish technique. J Arid Environ 7:75–92
Reichman OJ (1975) Relation of desert rodent diets to available resources. J Mammal 56:731–751
Soholt LF (1973) Consumption of primary production by a population of Kangaroo rats (Dipodomys merriami) in the Mojave desert. Ecol Monogr 43:357–376
Van Rooyen MW, Grobbelaar N (1982) Saadbevolkings in die grond van die Hester Malan-natuurreservaat in die Namakwalandse Gebroke Veld. S Afr J Bot 1:41–50
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kerley, G.I.H. Small mammal seed consumption in the Karoo, South Africa: further evidence for divergence in desert biotic processes. Oecologia 89, 471–475 (1992). https://doi.org/10.1007/BF00317151
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00317151