Beat Naef-Daenzer¹ & Chris M. Perrins²

1Swiss Ornithological Institute, CH-6204 Sempach, Switzerland, e-mail naefb@orninst.ch; ²Edward Grey Institute of Field Ornithology, South Parks Road, Oxford, UK, e-mail chris.perrins@zoo.ox.ac.uk

Naef-Daenzer B. & Perrins, C.M. 1999. Fledging and the ecology of the post-fledging period. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban: 1363. Johannesburg: BirdLife South Africa.

The proximate determination of clutch size, laying date and nestling growth by environmental variables has been widely studied. Much attention has also been paid to the evolutionary aspects of physiological and behavioural characteristics of reproduction. Our knowledge, however, is much restricted to the nestling period, whereas the ecology of the post-fledging period is still poorly understood. The moment of fledging changes the environment and the further development of the young birds in many aspects. New decisions have to be taken by parents and fledglings. Foraging, predation, population dynamics, mortality and dispersal during this phase of life are key issues for the understanding of reproductive systems and their evolution. New observation methods (e.g. molecular techniques, radio tracking) and data available from long-term studies offer new options to analyse both the ecological mechanisms involved and the resulting selection processes. The symposium draws attention to a widely open field of research. The five papers provide an overview of actual knowledge and open questions. The examples therein spotlight on a variety of aspects such as habitat use, foraging and predation, parent-offspring interactions, juvenile dispersal and mortality, sex bias in reproductive success and the evolution of reproductive systems.