View Full Version : Black Guillemots

13-Mar-08, 19:22
Had to think about this one.


Until i saw the family group.

13-Mar-08, 23:38
It looks like a gull/guillemot chimera.:confused I guess it is a juvenile?

14-Mar-08, 00:29
You can see back guillemots throughout the year. In winter their plumage is much lighter making them appear like the juveniles.

15-Mar-08, 14:15
Hi Seabird

You do not say when your picture was taken. But, if recently, then it is possible that you are correct in saying that the second shows two adults and an immature, but they are not necessarily a family party. Juvenile birds tend to disperse independently of their parents after fledging, so it is unlikely that a family party would stay together until this season of the year. These are probably unconnected birds sharing a common food source, which is quite usual round our coast outside the breeding season and you often see small gatherings of Black Guillemots feeding close together.

As so often, the moult sequence is a key to understanding what you are seeing. Adults undergo a complete post-breeding moult in the autumn (and then will look similar to the pale bird in your photo) and then moult into breeding plumage in March and April. So the two dark birds are adults. First year birds will normally start to moult into the black plumage later than the adults and may not complete the process until late June, although some will start to moult in March. Thus the pale bird is probably a first year but could be an adult that has yet to start its moult.

There is less pressure on first year birds to complete moult early, as they will not breed in their first year.