Behaviour of Black-throated Diver Gavia arctica and Red-throated Diver Gavia stellata during autumn migration stopover

The stopover behaviour of Black-throated Divers Gavia arctica and Red-throated stellata during autumn migration was observed in two sites Poland. Differences time-activity budget diving pattern were recorded from mid-October to mid-January 2004 2005. A total 1,516 minutes observation achieved. Birds spent their time (60.7%), followed by preening (14.8%), surface swimming (12.5%), other activities (12%). feeding similar. Immature birds had significantly longer dives than adults they made dive-pause intervals. This is suggested be caused the differences between age classes detecting capturing prey. Moreover, our results show that, autumn, first-year divers less foraging adult birds, instead spending more resting swimming.