Realistically our first reliable assessment of how good or bad this (2012) breeding season will have been will be when Gudmundur, Magnus and others in Iceland get access to some of the large flocks in western Iceland which will happen in the coming days.
Kathy Dickson a senior waterbird biologist at the Canadian Wildlife Service has reported that although she has no direct information on the performance of species breeding in the high arctic (~75 degrees N +), terrible weather in the low arctic (Baffin Island latitiude) lead to a poor breeding year for many species. The team working on Atlantic Brant (which look like ours, winter on the eastern seaboard of the US and breeding on Baffin and surrounding islands) had difficulty finding enough families to ring and many of the adults (failed/non-breeders) were already moulted and mobile. I agree with Kathy that this abundance of flying adults are probably adults that we would classify as 'failed' breeders who, because they have no reason not to, moult early.
Early moulters are mobile more quickly and one would have thought would thus migrate earlier. It wouldn't be a huge leap in imagination to think that this may have happened for 'our' Brent also.
Thanks to Kathy for this insight from the low arctic Brant in Baffin!