It’s that time of year (at least in the northern hemisphere) when birders fortunate enough to visit the coast once again get a chance to see one of the most funky ducks in the world - the marvellous Surf Scoter Melanitta perspicillata. Surf Scoters breed in Alaska and northern Canada (they’re the only species of scoter confined as a breeding bird to North America) and winter along the Pacific and Atlantic coasts from Alaska and Nova Scotia southward to Mexico and northern Florida - hence why there’ll probably be some 10,000 Birds readers who will have seen returning birds this very weekend.

Breeding-plumaged male Surf Scoters, Bolsa Chica, California. Feb 2008

I would imagine most birders will instantly recognise an adult male Surf Scoter - that enormous multi-coloured bill (which has given rise to a slew of colloquial names including Goggle-nose, Horse-head Coot, Plaster-bill, Snuff-taker, Blossom-billed Coot, Bottle-nosed Diver, Mussel Bill and (thanks Nate for reminding me) Skunk-headed Coot) is unmistakeable - but of course not all Surf Scoters are adult males…

In fact Surf Scoters come in a bewildering variety of guises, perhaps more so than any other common duck aside from the Mallard. They can be very tricky to age properly. Have a look at the photo of a typical group of Surf Scoters below and you’ll see what I mean…

Part of a mixed-age/sex flock of Surf Scoters (and a female Red-breasted Merganser),
Moss Landing, California. August 2008

I know that not everyone is ‘into’ aging ducks, but it’s surprising how much extra you can get out of birding if you give it a go (honestly). So, I’m going to try going beyond just saying “Oh, there are six Surf Scoters in the photo” and try and age them. Aging ducks when they’re asleep and hiding some key features is a bit risky, but - what they hey - I’ll take the risk and suggest that what we have here is a female, and what looks to me to be two 1st winter males, two second-winter males, and an adult male.

Why do I think that? Well, if I’ve interpreted the field-guides properly (and I’m not certain that I have to be honest) what I should be looking for is as follows:

• Females have brown to pale-brown eyes and dark bills. They look similar to juveniles (though they always have dark brown eyes), but as the other birds in the same group are so advanced it seems to me unlikely that the bird second from top is still in juvenile plumage, and should therefore be an adult. If I could see a pale nape and a dark belly it would definitely be an adult bird, but as I can’t I’m going with what I can see and deduce.
• Males take several years to reach adulthood, and the extent of both the white on the forehead and on the nape and the depth of colour in the bill increases with every moult. Males with smaller patches of white than full adults should therefore be younger birds.
• Older feathers often look ‘bleached’ and worn, and moulting birds often show a mix of scruffy paler feathers as well as darker ones. In combination with soft part (ie eye and bill) colours it should be possible to work out how old the birds are.

Using those criteria here’s the photo again but labelled this time:

Any comments either way from anyone better qualified than me?

Before the corrections come flooding in I may as well plough on. Now that I’ve got started on this I’ll have a go at aging some Goggle-noses I’ve photographed in the past (some of which are a darn sight easier than the half-sleeping birds in the large photo).

Juvenile/1st winter Surf Scoter, Bolsa Chica, California. Dec 2007

A juvenile/Ist winter on plumage but which sex? Is there a touch of colour coming into the bill (which would make it a male), or are those brown eyes a sign that it’s probably a female?

 

Ist winter female Surf Scoter, Bolsa Chica, California. Nov 2007

I don’t think this is an adult as the body feathers are paler brown than than the rich colour typical of an adult, and the pale tone of cheeks/lower neck seem to be too extensive.

 

1st winter male Surf Scoter, Moss Landing, California. November 2007

An immature but this one is clearly a 1st winter male: there’s already obvious colour in the bill and the whitish eye is also diagnostic.

 

1st winter male Surf Scoter (with a shellfish), Bolsa Chica, California. Dec 2007

A similar bird to the one above but photographed a month later (and several hundred miles south).

 

1st summer to 2nd winter male Surf Scoter, Moss Landing, California. Nov 2007

Superficially similar to both the above birds but I would think a year older - thus a bird in its second winter. Note the dark head with a hint of a pale nape coming through, and the more extensive whitish areas and pinkish colouration in the bill. It’s also interesting to note how the the dark spot at the base of the bill is becoming more clearly ‘circular’ and less smudged.

 

2nd winter/2nd summer male Surf Scoter, Bolsa Chica, California. late-Jan 2008

Another second-year bird (?) - though it’s difficult to say when a putative 2nd winter bird becomes a 2nd summer when it shows such a mix of old and new feathers (which creates the mottled effect). Note though the all-dark head, and again that the dark spot at the base of the bill is clearly ‘circular’ and less smudged than in younger birds.

 

2nd year male Surf Scoter, Bolsa Chica, California. Feb 2008

This bird appears far more advanced than the individual above, but was photographed at more or less the same time. It appears to have worn wing feathers and to have not attained the full amount of white on the head and is therefore possibly a second-summer bird….

 

 

2nd year male Surf Scoter, Bolsa Chica, California. Feb 2008

…but, all is not quite as it seems as this is the same bird just seconds later photographed as it dives - and it quite clearly has a broad white nape patch not visible in the earlier photo! Does that make it a 2nd summer or a worn adult?

 

Adult female Surf Scoter, Bolsa Chica, California. Jan 2008

 

I could have got that all hideously wrong, so please feel free to comment and perhaps we can get the correct answers together!

 

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Surf Scoters, Vancouver. May 2006

Rarely diving in water that exceeds 30 feet deep, Surf Scoters forage - as you’d expect from the name - in the zone of surf/breaking waves, and habitually dive through foaming wave crests. Gulls, especially Glaucous-winged Gulls, often force surfacing ducks to relinquish their prey, thus flocks frequently dive in unison as re-surfacing groups are less likely to be kleptoparasitized than individual ducks due to the swamping effect. Blue mussels constitute nearly 30 percent of their marine diet - the stomach of one scoter was crammed with 1,100 small blue mussels. Immense rafts congregate in regions supporting extensive mussel beds. Hundreds of thousands winter in the coastal waters off British Columbia alone, and 200,000 scoters could consume about 43 tons of mussel meat daily (adapted from http://www.virtualbirder.com/vbirder/ibis/SUSC/SUSC401.html)

According to Birdlife International the species has a large range, with an estimated global Extent of Occurrence of 1,000,000-10,000,000 km². It has a large global population estimated to be 400,000-600,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.

All photographs copyright Charlie Moores 2008