TIMING OF WING MOLT IN GREYLAG GEESE ANSER-ANSER IN RELATION TO THE AVAILABILITY OF THEIR FOOD PLANTS

The moulting period of Greylag Geese in the Oostvaardersplassen, The Netherlands, coincides with a period of rapid growth in their food plant Phragmites australis. During moult there is a continuous decrease in quantity and quality of the available food stock. As a consequence of food shortage, a large number of late arriving Greylags did not moult in the Oostvaardersplassen, but showed a reversed migration back to Scandinavia. The significance of this phenomenon is discussed in relation to the phenology of the food plants at different sites in Europe.