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During the last 20 years studies of various mammals and birds have shown that social organization is highly variable between and within species, and that such variation can frequently be explained on the basis of variation in food habits and food dispersion. This study is an attempt to discover the major ecological pressures affecting social organization and reproductive fitness of Arctic foxes in Iceland. Foxes were both studied at an individual level, by monitoring movements of radio-tagged foxes and observation of fox behaviour in demarcated study areas, and at the population level, by analysis of available foxhunting records, as well as material and information provided by foxhunters. The most common form of social organization was found to be a breeding pair, while social groups of 3-4 individuals also occur, particularly in coastal habitat, which is more productive and spatially more heterogenous with respect to food dispersion, than inland habitat. The Arctic foxes were found to occupy well defined, but fairly flexible group territories, whose borders were advertised by olfactory, auditory and visual signals. In one coastal region, three such territories ranged in size from 8.6 km² to 18.5 km², while there was an indication that territories were larger in inland habitats. In coastal habitats, foxes feed mainly on oceanic prey and do not show cycles in abundance. In inland habitat, foxes show a functional response to the 10 year population cycle of ptarmigan (Lagopus mutus), their main prey in winter. Litter sizes remain stable, however, due to little interannual variation in the foxes' summer diet, which consists mostly of migrant birds. Mean litter size at birth is 5-3 ± 1.7 S.D. and mortality from factors other than foxhunting is about 15% up to the age of weaning. Annual mortality in adults is about 50%, mostly due to foxhunting. Most vixens breed already as yearlings, while dog-foxes are more likely to show delayed breeding. In inland habitats there is balanced polymorphism with regard to colour morph, but in coastal habitats blue foxes have an overall selective advantage. Inland foxes are smaller than coastal foxes. Both size and colour affect reproductive fitness.

Thirteen badgers and 20 foxes were radio-tracked in the Wytham Estate, Oxfordshire, between 1981 and 1983. Thirteen badger and 10 fox groups were identified from radio-tracking and bait marking. Badger groups (mean size 1982: 4.45, 1983: 5.82) occupied contiguous territories (size: 22-75 ha) with boundaries marked by latrines. Seasonal variation in marking intensity and choice of marking sites presumably were responses to changing intrusion pressure. Fox groups (mean size: 2.6) occupied stable territories (size: 22- 104 ha) with little overlap. Faeces deposition by foxes facilitated territory marking. Earthworms (Lumbricus terrestris) dominated the diet of badgers (63 % estimated dry weight EDW, faeces), followed by cereals, fruits and other Invertebrates. Diet was highly variable between groups and seasons. For foxes, lagomorphs (20 % EDW) and earthworms (33 % EDW) were the most important prey, followed by scavenge and fruits. Variation in diet between groups and seasons was marked in lagomorphs but not earthworms. Multlvarlate analyses of habitat parameters revealed a low-dimensional 'resource space' that could be divided into conventional habitat categories. Censuses of prey species indicated that resource presence varied consistently between habitat categories. Key habitats occurred at fairly constant proportions in territories of both species) their dispersion partly determined the configuration of territory boundaries. The proportions of specific habitats per territory were correlated with the proportions of certain prey items in diets. space use by individuals was analysed by spatial autocorrelation methods, variation in space use by foxes was attributed to variation in resource dispersion. In contrast, individual badgers were similar in their use of space. Here, small-scale heterogeneity in intensity of use may reflect local earthworm availability, in one studied fox group, males and females differed in range use. Individuals in one studied badger group coordinated their use of space probably to minimize foraging interference. It is suggested that group living in Wytham badgers is a response to defending resources, and a model is proposed to explain how the spatial and social organisation of male and female badgers relate to the characteristics of the resources they require.

Thesis (Ed.D.)--Duquesne University, 2007. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 111-114) and index.

Thesis (Ph.D.)--Michigan State University. Dept. of Plant Biology, 2008. / Title from PDF t.p. (viewed on Mar. 30, 2009) Includes bibliographical references. Also issued in print.

Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: David W. Bowen. Includes bibliographical references (leaves 94-102).

Issued also as Thesis (Ph. D.)--Columbia University. / "I have given especial emphasis to the period of the editorship of Fox."--Pref. "Appendix: Identification of authorship": p.[394]-428. Bibliography: p. [429]-438.