Right from the start of this century, field observations and the patient ringing of birds have made available a growing mass of data on the breeding and resting areas of migratory species and on the course, period and duration of their seasonal flights. Considered as a whole, this work on migration morphology commands admiration, and when view­ ed in detail it reveals fascinating insights into the extraordinary naviga­ tional performances of many bird species, which find their way over enormous distances. Yet only a few dozen physiologists are actively trying to answer the question of how these performances are achieved. Experimental work on migratory birds raises many difficulties, some of them insuperable, so that many researchers carry out their experiments on the homing pigeon, which is constantly motivated by homesickness and ready to display its ability to flyaway home. Many of the problems connected with bird navigation are still un­ solved, but a rapidly growing body of results is being produced along with a variety of new ideas and approaches. A clear majority of the stu­ dents of bird navigation met in September 1981 in Tirrenia, a seaside resort on the Tyrrhenian coast, where each of them offered new in­ sights into his or her recent investigations. Their contributions have been connected in this volume, which provides an up-to-date conspec­ tus of the stage reached by research in this field.

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Migration and Migratory Orientation.- Do Migrating Birds Fly Along Straight Lines?.- Nocturnal Landbird Migration over Southern Ontario, Canada: Orientation vs. Wind in Autumn.- Spatial Distribution of Migrating Birds and Small-Scale Atmospheric Motion.- The Effects of Overcast Skies on the Orientation of Free-Flying Nocturnal Migrants.- The Migratory Orientation of Garden Warblers, Sylvia borin.- Interrelation of Magnetic Compass, Star Orientation, and the Sun in the Orientation of Blackcaps and Robins.- Age-Dependent Orientation in Migratory Birds.- Adaptive Temporal Programming of Molt and Migratory Disposition in Two Closely Related Long-Distance Migrants, the Pied Flycatcher (Ficedula hypoleuca) and the Collared Flycatcher (Ficedula albicollis).- Locomotory Activity of Day-Migrating Finches.- Homing of Pigeons.- Is There Evidence for a Magnetic Map in Homing Pigeons?.- Magnetic Navigation in Pigeons: Possibilities and Problems.- The Effect of Magnetic Anomalies on the Homing Behaviour of Pigeons: An Attempt to Analyse the Possible Factors Involved.- Homing Pigeons' Behaviour in the Irregular Magnetic Field of Western Switzerland.- Pigeon Homing: Effect of Altered Magnetic Field During Displacement on Initial Orientation.- Olfaction and Homing in Pigeons: Ten Years of Experiments.- Pigeon Orientation: Experiments on the Role of Olfactory Stimuli Perceived During the Outward Journey.- Pigeon Homing: Effects of Differential Shielding of Home Cages.- Pigeon Homing: New Experiments Involving Permanent-Resident Deflector-Loft Birds.- Reflected Light Cues Generate the Short-Term Deflector-Loft Effect.- Pigeon Orientation: A Preliminary Evaluation of Factors Involved or Not Involved in the Deflector Loft Effect.- Homing to Würzburg: An Interim Report on Long-Term Analyses of Pigeon Navigation.- Distribution of Release-Site Biases Around Frankfurt a. M. , Germany.- Comparative Investigations of Pigeon Homing in Germany and Italy.- The Role of Outward-Journey Information in the Orientation of Homing Pigeons.- Dependence of the Homing Pigeons' Initial Orientation on Topographical and Meteorological Variables: A Multivariate Study.- Study of Homing Pigeons in Brazil: Some Preliminary Results.- Variations of Nocturnal Performance in Pigeons.- Homing and Non-Migratory Orientation of Other Species.- Further Complexities in the Fixed "Nonsense" Orientations of Mallard.- Homing by Path Integration.- Do Geese Use Path Integration for Walking Home?.- A Comparative Approach to Bird Navigation: Implications of Parallel Studies on Mammals.- Homing Experiments with Starlings (Sturnus vulgaris) Subjected to Olfactory Nerve Section.- Spatial Memory in a Passerine Migrant.- Sensory Aspects.- Magnetic Sensitive Pineal Cells in Pigeons.- A Search for Magnetic Field Receptors in Animals.- Is the Avian Eye Pecten a Magnetic Sensor?.- Functional Status and Credibility of Avian Olfaction.- Activity of Central Olfactory Neurons in the Pigeon.- Infrasounds: A Potential Navigational Cue for Homing Pigeons.