Is this a Lesser Scaup...?

 I heard of a female Lesser Scaup on Lake Biwa in early January but at the time a local Scaly-sided Merganser had priority as I hadn't seen one for over 30 years! Since then I've looked for the reported Lesser Scaup on nine occasions without success. The single image of the bird I was emailed looked persuasive, a distinctive-looking individual which I'd have picked out easily had it still been there. By there I mean the general area it was originally seen, Lake Biwa is a vast body of water and it could easily be elsewhere on the lake. 

However, my efforts to find it have turned up an adult male Greater Scaup x Tufted hybrid, a possible first winter Lesser Scaup, which may also have been a hybrid but is no longer present to confirm to either way, and the subject of this post.

Basically, it looks pretty good for an adult female Lesser Scaup, but is it?

Though I've watched this bird for over 16 hours in total, getting adequate views, let alone good ones, isn't easy; how far out the flock is resting, the light conditions (conditions have ranged from too dull and snowing through looking into the sun - that's every afternoon) and trying to keep on the bird when it's continuously disappearing behind high waves. Then there's its frustrating refusal to flap or stretch its wings. And not least of all is the problem of locating it in the first place, I've found it along a four kilometre stretch of coast favoured by aythya on only four of my visits. 

I've never been accused of being a big duck fan, so coming late to ducks I'd place aging and sexing many species on a scale of less straight forward than I'd like to downright difficult; aging female-type scaup is closer to the downright difficult end. I considered both male and female first winter as possibilities for this bird before settling on adult female. I may be missing something but the yellowish eye must belong to either a male or older adult female (over two years old as far as I can discover), as there are no signs of any retained juvenile plumage I rule out a tardy first winter male and an older male should be easily recognizable as such. Thus I'd deduce adult female but I'm happy to stand corrected.

I've never seen a female Greater Scaup hybrid. Not being a duck aficionado, the chance of me ordinarily noticing a female scaup hybrid while casually scanning through a raft of ducks is probably akin to me having the winning lottery ticket in my back pocket. I don't buy tickets. I have found two male hybrids in the past but both had giveaway stubby crests, the current drake is the first I've seen which has a more Lesser Scaup-like head shape. All these birds, including the present one, were comparable in size to Greater Scaup. Because they are males? This possible Lesser is small, but then it is a female so perhaps that doesn't count for too much? Having said that it is very small, small even when compared to many Tufted Ducks. My sample is vanishingly small but I'd expect a female Greater Scaup x Tufted hybrid to look at least as large as the average Tufty considering the males of this combination are all larger.

There are still two important features I still need to photograph, one of them even to see clearly. 

Firstly the wing pattern (above and below), because as I mentioned it never flaps or stretches its wings. Some days the ducks are already asleep in rafts off-shore around dawn, though on one occasion most didn't fly in until 10am, not that this bird was with them that day. As there's no chance of picking it up head-on in a flock of incoming ducks it matters little whether it's already arrived or not. Once they have arrived some birds preen briefly before getting their heads down for the day, unless something startles them into having a brief look around. Then in the last hour or so of daylight they begin to stir. My last visit was typical in this respect, around 16:00 the section of the flock the bird was in began to get their heads up, most preened with a lot of wing flapping and stretching while 'my bird' blissfully slept through all this activity. They then swam out towards the middle of the lake, and yes of course, my bird still kept its head down all the way. The group finally paused and a couple of birds began diving, others flew off altogether, this was already scope-only distance. The light was getting very poor by the time 'my bird' suddenly took off without any post-sleep/pre-flight stretching. Unbelievably the Greater Scaup next to it also took flight cutting across my bird resulting in a near collision with both crashing back into the water. How often do you wait 16 long hours for a glimpse of a duck's wing? How often do you see two ducks collide on take off? Unbelievable. That's it, a distant split second view in failing light is all I've seen of the wing. I did get a a few shots, the Greater Scaup clearly has a full white wingbar, while the other bird appears to have contrast between white secondaries and grey primaries but under these conditions it has to remain inconclusive.

Secondly the bill. I've seen this reasonably well but not quite well enough to be 100% sure about how much black there is at the tip and the exact distribution of that black. I need a good photograph but up till now my best images aren't sharp enough when cropped to be of much help. Head-on images show the bill tip being blacker than it actually is, while images in profile or near profile minimize the true extent. As far as I can tell, the whole of the nail is black, and probably just off the nail but how much off is the point most in need of clarification, then towards the top of the nail small but distinct spurs jut horizontally in both directions and this is mirrored by a more prominent marking along the top of the 'lip'. I could liken the pattern to a mast and two yards of a sailing ship or the Cross of Lorraine without the long stem. Because the bird has its head down almost all day it's difficult to get good bill shots particularly as its head is often back down again before I've located the bird through the view finder, so I'll often simply stick to scope views.

Apart from those two points that need sorting out, the only possible negative which might indicate hybrid origin is less white around the bill than adult female Greater Scaups show. Though Lesser does tend to have less white apparently. How much less is acceptable? As with the bill, there aren't so many opportunities to get well lit shots at suitable angles when the bird is close enough to see detail.

So, over 16 hours still with no wing or bill pattern; this bird is a tough one. I had been planning to try again today but with the forecast predicting gales coming across the lake and overcast with a possibility of snow there isn't any point in trying.  

So here is a selection of images achieved under the best viewing conditions.

This gives a good indication of size compared to Tufted Ducks. Watched over extended periods the bird is clearly small, I'd say similar to a smallish female Tufted.

This soft early morning light allows for the best possible appreciation of features.

A similar view but a more cropped image.

A couple of points here: it seems to look proportionately large headed, it sometimes does. Could this be due to hybrid influence or merely due to birds having extensile head shape? Facing into the light also highlights the extent of white at the base of the bill (this isn't obvious in shadow), there are three main areas, one the centre forehead with fine brown intrusions at the 'top corners' separating this from relatively narrow vertical patches extending down to the gape. There is also a small amount below the lower mandible at the gape but none along the chin.

Female-type Greater Scaup have a range of variable plumage features, the possible Lesser (right) is quite unremarkable compared to them, it's a very typical female scaup appearance other than the reduced white around the bill base.

Another shot in which the bird seems large-headed. In terms of plumage, there's nothing to suggest it isn't a Lesser Scaup as far as I can see. The vermiculations are clearly scaup-type and not influenced by Common Pochard.

An interesting shot even if only because of the male Greater Scaup x Tufted Duck hybrid in the top right corner. The possible Lesser, again, looks small compared to everything else in the shot.

Two reasons to include this shot, most importantly it's a very rare occasion to see any neck. Normally when startled it turns its head forwards but doesn't extend its neck at all. There isn't really a second reason, other than the three foreground ducks look to me as if they are swimming downhill! So much so I tried to tilt the image when I first saw it. 

Another shot that gives a glimpse of neck and appreciation of the head and bill shape.

There is still the series of five heavily cropped images of the bird attempting to take off after the light had deteriorated. I was looking through the camera at the time, I was aware if I switched to the scope I'd never find the bird quickly enough through the camera view finder if it did decide to finally stretch its wings, so there's nothing I can add in terms of detail. You have as much to go on as me, so for what they're worth, here they are. The bird starts off on the left and ends up on the right.

There can be no doubt the Greater Scaup has a full white wingbar thanks to the final image, prior to that images suggest there's a contrast between secondaries and primaries on the bird in question but this is hardly conclusive.

I suppose the elephant in the room the the possibility of a Lesser Scaup x Tufted Duck hybrid. Has there ever been a record in Japan? I imagine this hybrid combination would be a rarer find than a Lesser Scaup even if it has been recorded here. Of course it is said the Tufted Duck x Common Pochard pairing can result in offspring very like Lesser Scaup but from what I understand they can be recognized by finer, Pochard-like vermiculations whereas this bird has typical coarser scaup-type markings.