Final Report

AGÜERO MARÍA LAURA

2016-10-01/2016-12-31

1-12

Biológica

Varios campos

1- Breeding biologyWe obtained unprecedented information about nest attendance, incubation behaviour and breeding biology parameters of Chubut Steamerducks, using (and tightening up) techniques with a minimum of disturbance.Chubut Steamerducks build their nests on the ground and we figured out that the first eggs are semi-buried covered with a few pieces of bush branches. The amount of downfeather increased as laying progressed. Females have a laying-egg frequency of 0.8 eggs.day-1 and apparently they complete clutch size (averaging 5.7 eggs) in one week. Females increase time spend on the nest with laying stage. Incubation constancy (percentage of all records during which the female was on the nest) averaged 77%, incubation period averaged 33 days and incubation temperature was 30.76°C in average.Recess frequency averaged 2.day-1 with an average length of 263 min. Most recessed occurred between 22:00 and midnight; and 03:00 and 05:30. During nesting season, we visited each nest just 4 times and females returned to the nest around 4 horas later. Hatching success was 0.87% and chicks survival 0.95%.We realized that nest abandonment probabilities are high during laying-stage and ?freezing? behavior increase as incubation progressed. Ducklings leave the nest no more than two days after hatching and the females drives them to the shallow water in front of the nest. We could observe biparental attendance of brood. Foraging ducklings are very vulnerable to attacks by several avian species including Kelp Gull (Larus dominicanus), Skua (Catharacta skua), and Giant Petrel (Macronectes giganteus). In this way, laying-stage, incubation and brood rearing period are very vulnerable periods for this particular marine duck.