Storm Isha and a Storm Wigeon

At the beginning of November a drake American wigeon was found at RSPB Cors Ddyga on Anglesey but was not seen the following day. When I saw the video, it immediately grabbed my attention because it was not just any old American wigeon, this stunning bird was a variant known as storm wigeon, which apparently occurs in one in every 500 - 1000 birds. Basically the crown and cheeks are so pale as to be almost white, making the iridescent green mask stand out even more than usual.  

Surely such a striking bird could not remain hidden for very long, yet it was five weeks before it was seen again, this time at Malltreath, also on Anglesey, where it stayed for four days before disappearing again. I desperately wanted to see this bird because I have a fascination with races and variants, but unfortunately I was in Madeira during this period and so had no opportunity to go for a look.

Another six weeks passed with no further sign of the storm wigeon, until finally today it reappeared at Burton Mere Wetlands, right on cue, in the teeth of Storm Isha which is currently battering the UK. Of course the storm didn't bring the bird here all the way from North America, it was already in the UK, but it did probably bring it off the Dee saltmarsh to the slightly more sheltered BMW.

I was not going to pass up the opportunity to see it locally and so after babysitting duties this morning I headed off to Wirral. I could have waited until tomorrow when I'll be working nearby, but given the bird's track record of short stays followed by disappearing acts for weeks, I thought it prudent to get there today. After all, it was first found nearly 12 weeks ago but has so far only been seen for six days in total during that period, including today. 

The bird showed well despite all of the usual problems associated with viewing from the BMW reception hide, e.g. viewing through glass and against the light etc.

A storm wigeon sheltering from Storm Isha! What a great bird. To be honest, I'd never even heard of storm wigeon before this bird arrived on Anglesey. If it had been just a plain old American wigeon I probably wouldn't have gone for it, but I was never going to be able to resist a storm wigeon on a day like today, it's just too good to be true!

These days with travel so easy that virtually every part of the world is accessible and with information overload on the internet, there's not much takes birders by surprise, but this bird certainly did. With most like me having never even heard of storm wigeon, the possibility of it being a hybrid was discussed, with Eurasian wigeon x Chiloe wigeon perhaps the most likely option. However, according to my books (esp. Madge, S. & Burn, H. 1989. Wildfowl: An identification guide to the ducks, geese and swans of the world. Helm ), these hybrids tend to have the whitish crown ending squarely on the upper forehead rather than tapering gradually to a point on the rear crown or nape as is the case with pure American wigeon, and the dark green mask is more extensive, covering more of the cheeks. The general consensus is that this is simply a pure American wigeon with a very pale head. That's certainly what I believe.

Exactly why one in 500 - 1000 American wigeons look like this is uncertain and it may just be that they are very old drakes.

I've heard it said that since it is such a striking bird, this variant is more likely to be kept in collections. Personally I find this unlikely because as I understand it, the pale head is a feature which cannot be bred, it just occurs occasionally and it may even be just an age thing, so even if you managed to acquire a storm wigeon, it's offspring would almost certainly be just normal American Wigeon. Presumably even in captivity only one in 500 - 1000 birds are this variant. What I can say from my observations, videos and photos is that it certainly does not appear to have a ring.