Trophic relationships of the common vole in cultivated fields

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Wiley and Nordic Society Oikos are collaborating with JSTOR to digitize, preserve and extend access to Oikos.-1986a. Predation causing synchronous decline phases in microtine and shrew populations in western Finland.-Oikos 46: 124-127.-1986b. Gradients in population fluctuations of Tengmalm's Owl Aegolius funereus in Europe.-Oecologia (Berl.) 69: 195-201.-1989. Breeding performance of Tengmalm's Owl Aegolius funereus: effects of supplementary feeding in a peak vole year.-Ibis 131 (in press).-and Norrdahl, K. 1987. Low proportion of shrews in the diet of small mustelids in western Finland.-Z. Sauge-tierkunde 52: 257-260.-and Norrdahl, K. 1989a. Predation of Tengmalm's Owls: numerical responses, functional responses and dampening impact on population fluctuations of microtines.-Oikos 54: 154-164.-and Norrdahl, K. 1989b. Avian predation on mustelids in Europe 1: occurrence and effects on body size variation and life traits.-Oikos 55: 205-215.-and Sulkava, S. 1987. Diet and breeding performance of Ural Owls Strix uralensis under fluctuating food conditions.-Ornis Fennica 64: 57-66. Kotler, B. P., Brown, J. S., Smith, R. J. and Wirtz II, W. 0. 1988. The effects of morphology and body size on rates of owl predation on desert rodents.-Oikos 53: 145-152. Latham, R. M. 1952. The fox as a factor in the control of weasel populations.-J. Wildl. Manage. 16: 516-517.-1986a. Predation causing synchronous decline phases in microtine and shrew populations in western Finland.-Oikos 46: 124-127.-1986b. Gradients in population fluctuations of Tengmalm's Owl Aegolius funereus in Europe.-Oecologia (Berl.) 69: 195-201.-1989. Breeding performance of Tengmalm's Owl Aegolius funereus: effects of supplementary feeding in a peak vole year.-Ibis 131 (in press).-and Norrdahl, K. 1987. Low proportion of shrews in the diet of small mustelids in western Finland.-Z. Sauge-tierkunde 52: 257-260.-and Norrdahl, K. 1989a. Predation of Tengmalm's Owls: numerical responses, functional responses and dampening impact on population fluctuations of microtines.-Oikos 54: 154-164.-and Norrdahl, K. 1989b. Avian predation on mustelids in Europe 1: occurrence and effects on body size variation and life traits.-Oikos 55: 205-215.-and Sulkava, S. 1987. Diet and breeding performance of Ural Owls Strix uralensis under fluctuating food conditions.-Ornis Fennica 64: 57-66. Kotler, B. P., Brown, J. S., Smith, R. J. and Wirtz II, W. 0. 1988. The effects of morphology and body size on rates of owl predation on desert rodents.-Oikos 53: 145-152. Latham, R. M. 1952. The fox as a factor in the control of weasel populations.-J. Wildl. Manage. 16: 516-517. Liberg, 0. 1984. Food habits and prey impact by feral and house-based Domestic cats in a rural area in southern Swe-den.-J. Mammal. 65: 424-432. MacLean, S. F. Jr., Fitzgerald, B. M. and Pitelka, F. A. 1974. Population cycles in arctic lemmings: winter reproduction and predation by weasels.-Arct. Alp. Res 6: 1-12. Maher, W. J. 1967. Predation by weasels on a winter population of lemmings, Banks Island, Northwest Territories.-Can. Field-Nat. 81: 248-250.-1970. The pomarine jaeger as a brown lemming predator in northern Alaska.-Wilson Bull. 82: 130-157. Norrdahl, K. 1985. The population fluctuations of small mammals in Suomenselka and southern Ostrobothnia, western Finland, in 1969-84.-Suomenselain Linnut 20: 57-68 (In Finnish with summary in English). Pearson, 0. P. 1966. The prey of carnivores during one cycle of mouse abundance.-J. Anim. Ecol. 35: 217-233.-1971. Additional measurements of the impact of carnivores on California voles (Microtus californicus).-J. Mammal. 52: 41-49. Rosenzweig, M. L. 1966. Community structure in sympatric carnivora.-J. Mammal. 47: 602-612. Ryszkowski, L., Goszczynski, J. and Truszkowski, J. 1973. Trophic relationships of the common vole in cultivated fields.-Acta Theriol. 18: 125-165. Liberg, 0. 1984. Food habits and prey impact by feral and house-based Domestic cats in a rural area in southern Swe-den.-J. Mammal. 65: 424-432. MacLean, S. F. Jr., Fitzgerald, B. M. and Pitelka, F. A. 1974. Population cycles in arctic lemmings: winter reproduction and predation by weasels.-Arct. Alp. Res 6: 1-12. Maher, W. J. 1967. Predation by weasels on a winter population of lemmings, Banks Island, Northwest Territories.-Can. Field-Nat. 81: 248-250.-1970. The pomarine jaeger as a brown lemming predator in northern Alaska.-Wilson Bull. 82: 130-157. Norrdahl, K. 1985. The population fluctuations of small mammals in Suomenselka and southern Ostrobothnia, western Finland, in 1969-84.-Suomenselain Linnut 20: 57-68 (In Finnish with summary in English). Pearson, 0. P. 1966. The prey of carnivores during one cycle of mouse abundance.-J. Anim. Ecol. 35: 217-233.-1971. Additional measurements of the impact of carnivores on California voles (Microtus californicus).-J. Mammal. 52: 41-49. Rosenzweig, M. L. 1966. Community structure in sympatric carnivora.-J. Mammal. 47: 602-612. Summary. We propose that extrafloral nectaries may sometimes function to defend plants from ant-Homoptera mutualisms by weaning ants onto a plant-controlled diet of nectar. According to this hypothesis, extrafloral nectaries can be favored even in the absence of ant defensive behavior. As evidence we cite the following observations: 1) Many studies have shown no net, defensive benefit to plants of nectar feeding ants. 2) Many nectar-feeding ants tend Homoptera which are major plant disease agents and which may profoundly alter plant architecture and physiology. 3) Ants can be distracted from tending Homoptera by feeding them sugar and they may even destroy the Homoptera. 4) Nectar has very similar chemical composition to honeydew and its collection does not require the extensive husbandry that tending Homoptera does. 5) Nectar production has been documented to increase during infestations of Homoptera. 6) It is more difficult to produce chemical defenses against sap feeders than against chewing insects. Summary. We propose that extrafloral nectaries may sometimes function to defend plants from ant-Homoptera mutualisms by weaning ants onto a plant-controlled diet of nectar. According to this hypothesis, extrafloral nectaries can be favored even in the absence of ant defensive behavior. As evidence we cite the following observations: 1) Many studies have shown no net, defensive benefit to plants of nectar feeding ants. 2) Many nectar-feeding ants tend Homoptera which are major plant disease agents and which may profoundly alter plant architecture and physiology. 3) Ants can be distracted from tending Homoptera by feeding them sugar and they may even destroy the Homoptera. 4) Nectar has very similar chemical composition to honeydew and its collection does not require the extensive husbandry that tending Homoptera does. 5) Nectar production has been documented to increase during infestations of Homoptera. 6) It is more difficult to produce chemical defenses against sap feeders than against chewing insects. The adaptive function of extrafloral nectaries (EFN's) was for a long time the subject of controversy. The polemic was between those who believed that extraflo