The Biology of Moult in Birds

Lukas Jenni · Raffael Winkler

Sep 2020 · Bloomsbury Publishing

About this ebook

The first comprehensive review of all aspects of the biology of moult, drawing information from across the literature and in all birds, from penguins to passerines.

Feathers are amazing structures unique to birds and, for a variety of reasons, they need to be renewed periodically as a whole in a process called moult. During this process, all of the functions of plumage are impaired and most aspects of a bird's life are affected. Every moult determines a bird's appearance anew, and restores plumage efficacy for flight and insulation. Moult profoundly affects physiology and the organization of the annual cycle, and it constrains reproduction and migration. Given these major impacts, which are equal to the other annual challenges of reproduction and migration, it is surprising that research on moult has largely been so neglected a subject.

Lukas Jenni and Raffael Winkler have brought together the widely scattered results of studies on the processes and consequences of moult in birds. This book opens with an overview of the functions of plumage, and of feather maintenance and feather wear, and then introduces the two functions of moult: replacement of worn feathers and adjustment of plumage characteristics and appearance.

The body of the book then examines feather-growth and the physiology, energetics and control of moult, and how various other physiological processes interact with moult and may compensate for its costs. Significantly, the authors explain how variations in moult and feather quality affect a bird's overall plumage quality, and they highlight the resulting consequences in terms of physical performance, appearance and signalling. Finally, there is a review of all the various solutions that birds have developed to fit moult into the annual cycle.

This long-awaited book covers for the first time all aspects of the biology of moult and fills an important gap in the literature, completing our understanding of how the most important annual events in a bird's life fit together into a coherent whole. It draws on a wide range of information – from penguins to small passerines, from raptors to wildfowl – to highlight the variety of the subject and to pinpoint the many gaps in our knowledge along with avenues for fruitful further research.

About the author

Lukas Jenni was born in Basel, Switzerland, in 1955 and became interested in birds as a boy. While studying biology at Basel University he became a volunteer at the Swiss Ornithological Institute and a ringer at the Col de Bretolet ringing station, where his interest in moult and ageing began while working with Raffael Winkler. His graduation study dealt with the morphology and ecology of the Great and Middle Spotted Woodpeckers. In 1979, he became head of the Swiss ringing scheme at the Swiss Ornithological Institute and gained his PhD in zoology with a study of the mass concentrations of Bramblings in winter in 1984. He became a lecturer at the University of Zurich in 1997 and a professor in 2013, and was appointed scientific director of the Swiss Ornithological Institute in 2000. His research focuses on bird migration and its ecophysiology, the ecophysiology of stress, and the moult of birds. He is also involved in many other projects at the Institute, and supervises studies in avian ecology and conservation.

Raffael Winkler was born in 1949 in Basel, Switzerland. Interested in birds since his early childhood, a stay at the Station Biologique de la Tour du Valat in the Camargue convinced him to study zoology. At the University of Basel he attended lectures in zoology, botany, palaeontology and psychology, and graduated with a PhD thesis on the pneumatisation of the skull roof in birds. The data for this study were collected at the ringing station at Col de Bretolet in the Swiss Alps, where he began a close co-operation with Lukas Jenni in the study of passerine moult, ageing and bird migration. Raffael was employed at the Swiss Ornithological Institute from 1975 to 1980, and managed the avifaunal information centre and developed outreach programs with amateur birdwatchers. During this time he was secretary of the Swiss Rarities Committee, and worked on The Atlas of Breeding Birds in Switzerland. In 1980 he was elected curator of the bird collection at the Natural History Museum, Basel, where he edited The Avifauna of Switzerland and carried on the Museum's own tradition in moult research. He retired in 2012 and now works as a voluntary ornithologist at the Basel Museum.