Raffael Winkler¹ & Tatiana A. Rymkevich²

Winkler, R. & Rymkevich, T.A. 1999. Moult in the annual cycle. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban: 526. Johannesburg: BirdLife South Africa.

Birds are the only vertebrates that regularly replace the most important part of their locomotory apparatus. This gives rise to a whole avalanche of consequences in the life of a bird to which other vertebrates are not exposed. Moult is just as challenging an event as migration or breeding. This symposium gives an insight into the consequences and effects of feather replacement. Thus, moult energetics show that the process does not only consist of mere exchange of feathers but is combined with a comprehensive renovation of body tissue. Feather loss and replacement inevitably leads to gaps in the wings and tail and alters form and loading of the corresponding flight surface. What are the effects on flight performance? Intraspecific variation in timing, duration and extent of moult is population dependent and the factors are subject to photoperiodic control. Several strategies for moulting either in the breeding range or the winter quarters, have been developed. The feathers of all birds have a limited lifespan and small and large birds have each developed their own way of preventing excessive wear.