SUSTAINED PAIRBONDS DURING MOLT MIGRATION - PAIR-FORMATION DURING BREAK-UP OF FAMILY GROUPS IN GADWALL ANAS-STREPERA

Males of the South-Bohemian breeding population of Gadwall do not moul t their flight-feathers in the Czech Republic but move 210-250 km WSW to Ismaninger Teichgebiet near Munich, Bavaria. Here in 1994 the earli est males had regained flight by 24.7. From 25.7., males in eclipse pl umage with freshly moulted wings were arriving in 3 fishpond areas nea r C. Budejovice, South Bohemia. On these ponds, the earlier 13 out of a total of 23 successful females were separating from their independen t offspring between 25. 7. and 5.8. At least 8 of these 13 females pai red up both inconspicuously and quickly, their males being present on the breeding ponds only 1-2 days. Attendant circumstances and behaviou r (see Tab. 2) support the hypothesis, that pair-bonds were interrupte d only for moult migration of the males. Females in any case will bene fit from being paired before their wing moult in Ismaning. Despite low body mass they are able to dominate over single males and juveniles c ompeting for food and to fuel up in time for autumn migration.