Basin Notes - September 2000

Coats of Many Colours (mostly Brown!)

Look in the clothes shops and what do you see? Autumn and winter gear. We know its coming so we can buy now in preparation for the rain and cold to come.

Look at the birds on the Basin and what do you see? Autumn and winter gear! They know by the days getting shorter that the cold weather is coming so they are changing into some nice smart, warm feathers.

Unfortunately, it takes birds up to two months to achieve this "change of clothes" as they moult their old frayed plumage and grow a nice new set of perfectly marked and neatly edged feathers. During this time they still need to avoid predators, feed and keep warm. The problem is, if you lose all your feathers at once you can no longer fly. If you can't fly, you can't escape from predators and finding food is more difficult. But you must get the new "winter coat" so what to do?

Some birds, like swans ducks and geese, accept the risk and are flightless for 2-4 weeks while they moult all their flight feathers at once. The Basin provides a safe haven for such birds as well as access to a good supply of food. Shelducks fly off to Heliogoland Bight to shed their feathers and return to the basin in smart new livery. Male ducks use their brightly coloured plumage to attract females but now such finery could attract the attention of a predator so they moult into some dowdy grey or brown camouflage patterns to "hide" from hungry mouths/talons while they are changing. This is called "eclipse plumage" and if you look at the eider ducks on the Basin at the moment you will not see a "proper" male anywhere - they are all in their brown and white blotchy disguises.

Other birds, like gulls, moult a few feathers at a time and are still able to fly, albeit less efficiently, and still find food. This make them look "scruffy" and the gaps in their wings are easy to see as they fly around looking for a tasty morsel.

Migratory birds have an added problem - moult before or after migration. Terns, whose creaking calls are noticeable all over town at the moment, are divided on the issue. Arctic terns wait until after migration while Common terns opt for a new set of feathers before embarking on a flight of thousands of miles.

Also, there are many juvenile birds around at the moment and they have not acquired their adult plumage yet - plenty to challenge beginner and expert alike. The Wildlife Centre has two new telescopes (kindly donated by Glaxo and North of Scotland Water Authority) to help you see the changing scene on the Basin.