Compilation which summarizes the enormous wealth of data and hypotheses elaborated in the huge research field on the control mechanisms which are involved in bird migration. This volume takes into consideration all aspects of controlling factors since 1925, when experimentation in the subject began. Starting from historical and methodological aspects it concentrates on endogenous programmes for migration and the underlying genetic and hormonal factors, and it treats photoperiodica, climatic, social and other influences. It also includes ecophysical relationships such as high altitude migration or the overcoming of migration barriers such as deserts. Finally, microevolutionary processes and the prospective competition of bird communities under the influence of global warming are outlined. A very important text, filling a real gap in the literature.