The introduction earlier this century of Norwegian reindeer to the sub-Antarctic island of South Georgia provided scientists with the unusual opportunity of studying the interaction between a large arctic herbivore and a southern ecosystem that had not previously been exposed to grazing by mammals. Originally published in 1988, this book synthesises the results of many years' research into this fascinating ecological situation. The author develops the observations into two main themes. First, a comparative study of the biology and ecology of a deer that occurs in a wide variety of Arctic habitats. Secondly, an investigation into the ways in which an introduced population adapts to a new environment, its relevance to the population ecology of mammals and to the conservation of southern island ecosystems. In doing this, the author discusses many topics including reproductive biology, feeding ecology, growth, mortality and population dynamics. This in-depth study of a single species in an alien environment will appeal to advanced undergraduate and postgraduate students, research workers in wildlife management and ecology, conservationists and polar scientists.