While many of you may think that an eclipse only happens for a fleeting moment many years apart, there is one eclipse that happens annually and millions of times over and you can come and see it right here at Saltholme.
Feathers, like clothes, wear out with use. If we were to wear the same pair of trousers everyday, (which there is nothing wrong with of course....) then we'd have to get a new pair every now and then as they wouldn't be fit for purpose. The same thing happens with birds. Body feathers wear and so keeping warm requires more energy while the abrasion of flight feathers means moving around takes more effort. This is obviously not a good thing so at least once a year, these feathers get changed for new ones. The process of replacing these feathers is called moult.
Different birds have different moult strategies depending on their life cycle but usually all feathers are replaced at least once a year. In some instances you wouldn’t notice birds moulting. Birds of prey take a long time to change their feathers and can ‘wear’ several different generations of flight feathers at the same time whereas many garden birds will grow change them entirely right under your nose (more about this in a few weeks time...).
The strategy we will be looking into is simultaneous moult where ALL the feathers get moulted at the same time. This is the most commonly seen type of moult at Saltholme, even though you might not realise you’re seeing it, as all our wildfowl undergo this process.
As the diagram above shows, any bird undergoing simultaneous moult is flightless throughout stages a), b) and c), making them an easy pickings for predators. So what does a brightly coloured male duck do to avoid being noticed when it can't fly away to safety? He moults all his body feathers to become not so brightly coloured. Looking more like a female for a few months of the year makes it easier for him to not be noticed when tucked away. When a male is well into his moult, this is called the eclipse plumage.
It may be easier to illustrate so here is a drake Teal going through the motions.
This is what many of our drakes look like as they start to moult. After 8 months of wear and tear, the plumage is pretty worn already but looks even tattier as feathers are lost. The new 'female type' feathers can be seen on his side.
Here he is in full (99%) eclipse plumage and looking very similar to the female. Generally male Teals in eclipse are darker with less spotting below and a weaker eye stripe. Fortunately we don't have to try too hard to look for either of those features in this picture as we can see he has one old stripey feather on his side. Once all his flight feathers are grown he starts his body moult all over again. Sometimes this can start immediately after the previous moult has finished. Because moulting takes up a lot of energy, it all depends on the food availability as to how quickly both moults are completed. The quicker he can get back to looking his best, the sooner he can start displaying to females and get paired up and ready for the Spring.
Talk about from rags to riches. It's not a quick road back to looking gorgeous. All male Teals will have to look as scruffy as this before they can reveal their finery once more. .
And when you look as good as this, it's surely worth going through it all. Absolutely stunning!
You can usually tell when ducks start to moult as they all seem to disappear, hiding away in vegetation and the pool edges when they are most vulnerable. The process starts any time from now onwards, the exact time often depends on breeding success. Any birds starting to moult in early July will more than likely be non-breeders or failed breeders. Most will start to drop their feathers in August and by the time November comes around all the males will have brand spanking new feathers and will look immaculate. A visit to Saltholme this week would have you thinking we've no ducks at all but now you know the truth! :)
So if you come and see us over the next few months and wonder where all the male ducks are, you now know that they're hiding in plain sight. To see them in pristine condition you'll need to come and see us again. A visit from November onwards will give you the opportunity to appreciate all their bright feathery newness (but don't leave it that long of course, there's plenty to see in the mean time.....)
The more you're out the more you see - https://twitter.com/BoyWonderBirder