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.

Baer's Pochard x Common Pochard and Ferruginous Duck x Common Pochard hybrids on Lake Biwa

EDIT: A 'new' bird was present 16 Feb and I've tacked on the end of the post.

 Since January of last year (2021) I've enjoyed an unparalleled opportunity (within my experience) to observe hybrids of these two combinations. There were often three birds coming into the same 'loafing bay' last winter. This winter two seemingly different birds were present in the same area in early December and they were joined by two more during January. Additionally, there were three other birds only four kilometres to the south, a couple of one-day birds in early November and another Ferruginous-type briefly in December. That's a scary number of hybrids within a very limited area of a vast lake, albeit an area particularly favoured by aythya.

But are they Baer's x and Ferruginous x Common Pochard hybrids, have I got this right? Well, I can't be absolutely certain, however birds with green heads and grey vermiculated bodies aren't likely to be anything other than Baer's x Common, and these birds have provided an crucial reference point. Others seem a good fit for Ferruginous x Common Pochard, but there are also birds that that are less easy to place and, if seen singly, would be even more problematic.  

Four hybrids together 27 Jan, 2022. It'll be clear from this shot that light conditions are as important as distance when it comes to getting meaningful views of the birds, let alone images. I had the benefit of scoping these birds for some time and for the record, I consider the right hand bird a Ferruginous hybrid, next to it is a green-headed and therefore Baer's hybrid and the other two have reddish-brown heads. I'm cautious about categorizing this type but Baer's x Common Pochard is the choice I'd lean towards.

Currently, there are four birds frequenting the same bay when not actively foraging. A green-headed bird (Baer's x), two with reddish-brown heads which look otherwise almost identical to the Baer's x, three peas in a pod springs to mind. The Ferruginous isn't so different at a glance either, so as it isn't possible to judge whether a bird is reddish-brown- or green-headed at any distance in dull conditions,  the pattern of the vent has become the easiest way for me to tell them apart. Each differs from the others even with the tail down, provided you can watch them at different angles. This is convenient for me to know which individual I'm looking at, but of no help from an identification perspective. 

So here are some of the best images starting with the green-headed birds; four images each of last and this winter's birds.

Four images of the same individual from 2 Jan 2021. I don't think there can be doubt about the progenitors in this case. If the birds are close enough, this neutral light can be best to assess details.

 

Reddish cheeks can be seen at close range with the sun behind the observer, not the case with the previous bird.

The same bird in poor light showing upperwing. A Ferruginous hybrid is in the foreground.

Moving on to the presumed Ferruginous x Common Pochard hybrids. The first was a lone bird (28 December 2021); three images. Followed by the bird present since late January; seven images.

At first I thought this must be one of the two brown-headed Baer's-types that had moved a little down the lakeside. However, when later checking the images I realized that it was a different bird and regretted not having spent more time with it. The reasons I now think this is a Ferruginous hybrid are its more compact appearance, it gives the impression of being shorter-bodied and sitting higher in the water. I'm tempted to simply say smaller size, which may well be the case, though that can't really be judged from the images. More significantly, the brown spilling from the breast onto the fore-flanks with very little change in colour (more obvious in the following image) seems indicative of Ferruginous as Baer's (and its hybrids) shows a sharp contrast at the breast side.

The eye is the darkest of any of the hybrids I've seen, though the brightness and colour tint of all the birds does change depending on angle and ambient light. It's worth noting that none of the hybrids have a truly white eye. The ventral markings showed this was a different bird to the presumed Ferruginous x that I first saw a month later.

 

The first view of the 'new' Ferruginous; 27 Jan 2022. The instant impression I got was of a much browner bird than the others I'd been used to seeing. Again the rather short-bodied and high-in-the-water appearance was apparent.

Closer views in better light; 2 Feb 2022. The overall brownness, yet again, depends on angle and lighting, it often doesn't appear as dark and brown as in this image and can look both lighter and greyer, particularly the flanks. Nevertheless, this image gives a more realistic overall appreciation when compared to the Baer's x Common Pochard hybrids and the similar reddish-brown-headed birds I'm tentatively calling Baer's x Common Pochard hybrids. In the field it almost looks a patchwork of even browns, this a result of the vermiculations of flanks and upperparts being less apparent and giving a less textured appearance. So, more uniform, slightly darker and browner flanks and noticeably darker and browner upperparts compared to the other hybrids present. The lighter and greyer impression it can give is always temporary. 

Here the Ferruginous (on the right) looks much closer in appearance to the reddish-brown (-headed) Baer's-type, though the flanks remain more uniform and the upperparts slightly browner. As the birds turn in the water the general similarity will pass and the Ferruginous regain its actual darker and browner appearance. Knowing these birds, I get a sense of the Ferruginous sitting higher and being shorter-bodied but realize to anyone viewing the image this can be dismissed as due to the angle and the possibility of unequal foreshortening, if recognized at all.  

And now to the more problematic birds, as mentioned in the first paragraph, which I'm tentatively calling Baer's x Common hybrids but are probably better left unidentified. These birds have reddish-brown heads which do not change as the winter progresses. My presumption that they are Baer's x Common Pochard hybrids is founded on them being essentially identical in size, structure and general plumage to the green-headed birds. The head colour is the sole qualitative difference. I do wonder about the shape of the head, it can look very pointed and often seems more suggestive of Ferruginous, but so, very often, does the shape of the green-headed birds. Though, as might be expected, these trickier birds can all show a browner or greyer cast to the upperparts, depending on angle and light. The only other diagnosable feature is the pattern of the ventral markings, and this seems to be random individual variation rather than moult related as there has been no change in appearance to any individual throughout winter. Four of the eight similar hybrids I've seen during the period have been this type, so perhaps this is the most likely type to be encountered as a single bird during winter; this as far as first filial hybrids are concerned of course.

The first bird, 2 Jan 2021; three images.

The second bird, 12 Feb 2021; three images.

The third bird, 2 & 11 Feb 2022; two images each date.

The fourth bird, 4 Feb 2022; three images.

Some questions:-

Have I come to the right conclusions as to the hybrid combinations?

Can eye colour be used to sex F1 hybrids? There are no strikingly white-eyed birds here.

If these birds are all males (?), then where are the females? Would a male Baer's x female Common produce a very different looking bird to male Common x female Baer's? In other words could these all be the offspring of male Common Pochard x female Baer's and offspring of the reverse gender pairing produce far more Baer's-like adults? The same can be asked of Ferruginous but if Baer's is declining in numbers and Ferruginous is not, it seems more likely that Baer's, whether male or female is more likely to be involved in hybrid cases even if Ferruginous x Common Pochard pairings aren't rare.

Are these birds all F1? Presumably so, they can't all be pale-eyed juveniles that are going to moult into something that could be mistaken for either of the putative progenitors.

Where are the F2 (and beyond), the back-crosses? This is where concern for potential misidentification of Baer's Pochard or Ferruginous Duck lies if the above birds are typical F1. There's no risk of misidentifying any of the above birds as anything other than a hybrid. But again, does the male of the progenitor pair have a significant influence on the appearance of the offspring?

I earlier mentioned a couple of additional birds I saw this winter which in the field I thought to be hybrids, looking at the images I began to have second thoughts but now the pendulum has swung back, and I have to accept that two potentially very interesting birds got away. If they were of mixed ancestry then missing out on the opportunity to get more details of their appearance is an even greater pity than missing out on Baer's and Ferruginous. Still, from a purely birding standpoint, finding both 'Baer's Pochard' and  a 'Ferruginous Duck' on the same day (only 18 minutes apart according to the photo data!) makes for a pretty good day; glass half full. Such a pity neither lingered, I wonder where they were headed?

The Baer's or Baer's hybrid, 4 Nov 2021; three images.

I may have been rash identifying this as a hybrid, though I think not. I did so because of the apparent paler markings on the upperparts, which could be nothing more than reflection (unlikely), as well as irregular, diffuse paler areas on the flanks, though plenty of ducks aren't in their prime the first week of November. It's just too distant to be confident about either way. If it is a hybrid, it's obviously not an F1 and therefore it's even more frustrating that this one got away.

Ferruginous Duck or Ferruginous hybrid, 4 Nov 2021; three images.

I'd put money on this being a hybrid. The images may not be as clear as I'd like but those consistent grey markings on the upperparts look perfect for grey stippling or vermiculations that are just beyond a comfortable distance to make out precisely. Another backcross viewing opportunity lost.

I'm always surprised how much time these hybrids spend in close proximity to each other; just coincidence? Are they more likely to select another hybrid as a mate? Even if they are this would only slightly limit dilution of the Critically Endangered Baer's Pochard's gene pool. Here are three images of a green-headed and reddish-brown-headed bird that that were never more than five metres apart, whether further out or closer in, during the two hours I spent there (11 Feb 2022).

Lastly, a possible Baer's x Ferruginous hybrid from five years ago (1 Dec 2016). When I first heard about this bird the message was the it was a male Baer's and there is certainly a close enough resemblance to render this a difficult bird to identify if seen way out on Lake Biwa rather than on a city park pond. 

Give this bird another 100m (or 300m...) and it would be looking pretty good for an early winter Baer's that hasn't acquired it's green head yet.

Fortunately it wasn't way out on a lake and at this range a few fresh feathers can be clearly seen on the crown... but they aren't the expected green. Bright reddish-brown fresh feathers contrast with the older, duller parts of the head which lack the reddish tints. This is beginning to look like a Baer's x Ferruginous hybrid.

But then there's the question of the extensive grey stippling on the upperparts. Could this indicate there was already Common Pochard influence in one (or both) of the progenitor pair? If nothing else, this bird shows the importance of adequate views with a suspected Baer's.

EDIT: Another bird turned up on 16 Feb. It stayed well out at the back of the flock but was suggestive of another Ferruginous x Common Pochard hybrid. I'm hoping for better views but no ducks were present on 18 Feb. That's no ducks, no Coots, absolutely nothing in this bay for the first time! In other loafing areas birds didn't start to arrive until 10am, much later than normal.

Three images of the new duck.

The new bird (back left) compared with one of the reddish-brown-headed tentative Baer's x (front right). The breast of this new bird is a distinctly paler brown than any of the other hybrids and the head a much clearer, brighter red. The eye may be duller and/or redder but closer views are needed to be sure.