The DBQ that just won’t die

16 04 2015

After posting the photo of the headless carcass with dusky reddish legs, it appears we now have a consensus on Bird B. The underwing of the headless carcass bears the classic pattern of an American Black Duck–white overall, with several distinct dark brown feathers at the wrist joint. With that in mind, looking back at the foot of Bird B, it looks like it too is very likely an American Black Duck. And in fact, when I posted the original DBQ, I was able only to access that single foot photo. Now that the database is fully up and running again, I found this photo as well:

Additional evidence as to the identity of Bird B. Open and shut case, with that speculum bordered in dark!

Additional evidence as to the identity of Bird B. Open and shut case, with that speculum bordered in dark!

And the case for Bird C was sealed by that additional photo–this bird was a Red-breasted Merganser.

I am in the last, thrashing weeks of the semester, readers, so please bear with me on the paucity of blog posts and the slowness of my email responses! Two weeks left until classes end and I turn my attention elsewhere. SEANET being a province of elsewhere, in case you wondered.





DBQ answers

9 04 2015

All respondents quickly recognized Bird A’s distinctive beak–heavy, straight and dark. This is a Common Loon. I wanted to show this picture mainly since it makes visible the very slight mismatch in length between upper and lower beak that one can rarely appreciate in a live bird at a distance. In fact, the upper bill does project just a small way past the lower (the bill is pictured upside down in our Bird A).

Bird B, found by Sue Bickford in Maine this month.

Bird B, found by Sue Bickford in Maine this month.

As for Bird B, where we have only a foot in this image, I was intrigued by the coloration here. The foot looks like a duck’s, and in fact, there are red or dark orange footed ducks in the world, namely scoters and mergasers. For more on that, see previous post on brightly colored feet. There are also terns and guillemots that may have red feet too, but our Bird B looks to have a duck foot to me. So Bird B here has a reddish looking foot. But something about it was bothering me. I could not quite square the color with the shape and proportion of the toes. I could not square this bird with a scoter, basically. Wouter and Edward had the same conversations in the comment thread as what went on in my mind–is this foot actually red, or has the desiccation process altered the original color? Then, fortuitously, I received a photo of a different bird: a headless carcass found by Louise Nelson, walking Plum Island in Massachusetts. The feet on this bird looked rather similar in proportions and color, and here we had more information on the rest of the bird, though not the head. But we Seanetters know not to ask too much. Here’s that bird’s picture:

Headless bird with vaguely red feet. If you squint? (Photo: L. Nelson)

Headless bird with vaguely red feet. If you squint? (Photo: L. Nelson)

To me, those feet also had a sort of dusky red hue to them, similar to Bird B. At the risk of dragging this out overlong, what do you think of that, readers? Are you convinced? And if yes, then what would that make Bird B? I have my thoughts, naturally.

Finally, Bird C, which generated some healthy debate as well. The two candidates were American Wigeon and Red-breasted Merganser (two votes for the latter, from Wouter and James Taft). Much hinges on how we interpret what we’re looking at in this case–the twisted up wreckage of these wings makes it challenging to sort out what’s upper wing, and what’s under, what’s covert and what’s secondary. Overall, a wigeon underwing is fairly light, with some brownish feathers along the margin of the wing’s leading edge. That is consistent with what we see in Bird C, but is also consistent with a Red-breasted Merganser’s underwing. A key difference, as both Wouter and Edward pointed out, is whether we are seeing a white speculum on the secondaries of the underwing or not. The merganser has one; the wigeon does not. I can see the problem though–might that white patch actually be not the secondaries themselves, but ┬áthe coverts, and the dark secondaries have gotten somewhat bunched up behind them?

Then we have that view of the very disheveled right wing, where all we can really make out is that there is a large white patch. Wigeon and merganser both have that. So, what to do? The answer–go back into the database and discover that Wendy Stanton actually took more than one photo of this specimen. Here’s the other:

SEANET gods' blessings on Wendy for taking this very illuminating photo.

SEANET gods’ blessings on Wendy for taking this very illuminating photo.

That helps rather a lot, no?





Dead Bird Quiz: ultrasuper closeup edition

3 04 2015

I’ve gotten some very nice macro shots of dead birds lately, showing some nice detail of parts of carcasses. I decided to include some among a few of the more standard sorts of DBQ fodder. Here they are, friends!

Bird A, found by Jerry Golub in Florida last month.

Bird A, found by Jerry Golub in Florida last month.

Bird B, found by Sue Bickford in Maine this month.

Bird B, found by Sue Bickford in Maine this month.


Bird C: Found by Wendy Stanton in North Carolina last month.

Bird C: Found by Wnedy Stanton in North Carolina last month.





The bays give up their dead?

27 03 2015

Over much of this winter, I heard from Seanetters telling me they were finding what seemed like fewer dead birds on their beaches. This was mainly from the “hotspot” beaches that typically produce a few birds per walk throughout the winter, when bird mortality is generally highest. Many of these Seanetters went many weeks without finding any birds. Now, as spring advances, our northern cohort of Seanetters are seeing the opposite in many places–sometimes over a dozen birds dead on a stretch of beach. We are also hearing from nature centers and other groups who are receiving reports from the public about what seems like a spike in mortality. So is it?

Before I begin, I offer the caveat that we have not actually analyzed these numbers since they are only now coming in, but I can give some impressions and some hypotheses. First let’s look at what’s been turning up. On some beaches, it seems that a particular species dominates among the carcasses. Ray Bosse, walking along Buzzard’s Bay in Massachusets, found eleven Canada geese on his beach on March 22. Ray’s beach does not typically turn up many birds. Compare these snapshots from our database for Ray’s beach during the winter of 2014 vs. the winter of 2015:

RBosse_winter2015
RBosse_winter2014
2014 was a fairly typical year for Ray–a few birds here and there. 2015 looks a bit different. Ray found no birds from November though the end of February, and then an uptick began, culminating in that big day on the 22nd. Compare Ray’s numbers with those of Warren Mumford, walking in Chatham, MA, a part of the Cape facing out toward Nantucket. Warren’s beach is a fairly reliable producer of dead birds, though not in huge numbers all at once. Then, on March 25th, he too saw a sudden influx, finding 17 dead birds on his beach.

MA_27_winter2015
These kinds of spikes draw our eyes, but are they reflecting current, ongoing mortalities, or something else? To figure that out, we need to look at just what kinds of birds were found on each beach, and in what condition they were in. When we do this, we find some differences between beaches. On Ray’s big day in Buzzard’s Bay (a fine title for a morbid children’s book about bird carcasses), he found mostly one species–Canada geese (CAGO). Warren, however, found a grab bag of different species, basically representing the usual species that turn up on his beach: eiders, White-winged scoters, and gulls. When we see so many different species, it does not rule out a disease process, or other common cause of death, but it makes it far less likely. Few causes would impact everything from American Black Ducks to Herring Gulls to Common Eiders. The other point to consider is the condition of the carcasses. Warren’s birds, in addition to being all sorts of species, are in varied states of decomposition and degradation. Some are very weathered, and almost mummified. Others are intact, and look fairly fresh. This tells us that these birds did not die all at the same time.

WMumford7220-20399[1]

A weathered Common Eider carcass. Likely many months dead.

A much more recently dead juvenile gull.

A much more recently dead juvenile gull.

We appear to be seeing accumulated mortality over time, but revealed to us all at once.

In Ray’s case, the geese are all at just about the same level of degradation, suggesting they died within a much narrower timeframe. Multiple specimens of one species, and all dying around the same time raises our eyebrows a bit higher. For this reason, we are planning to collect a few of these geese and perform necropsies on them. The condition of the carcasses will preclude any advanced diagnostics, but we can hopefully look for signs of trauma, and also assess the nutritional state of the birds. It is very possible that the cause of death in these birds was starvation. The harsh winter, one in which many of our sheltered bays (and not so sheltered ones) actually froze over entirely, and massive snowfalls this year, severely reduced the available grass forage for the geese. It’s our current, working hypothesis. Even if the birds died over the course of a few weeks or even a month, the cold and the ice would have preserved them fairly well. They may even have been on the beach the entire time, just concealed by ice and snow and only now becoming visible. This effect might be expected to be even more pronounced in the bays where dead birds were entirely prevented from washing up by the extensive ice sheets from late January through just a week or so ago. On ocean facing beaches, where open water persisted all winter, are these spikes due to birds that were dead on the beach but hidden by snow? Or are these birds drifting in from other previously ice-locked areas?

What even the larger bays looked like this winter. How many dead birds could be locked in that ice?

What even the larger bays looked like this winter. How many dead birds could be locked in that ice?


If the ice-imprisoned carcass hypothesis is correct, then these high numbers of dead birds on many beaches may represent weeks or months worth of mortality all released at once for the finding as the ice and snow rapidly melt. I look forward to seeing what we find in the CAGO from Ray’s beach to see if we seem to be on the right track in our line of thinking. Watch this space for more news.





DBQ, part deux

17 03 2015

I have feeling so very remiss about SEANET lately, not least because I cannot blog as frequently as I might like during the high teaching season. To partly make up for this, in this second installment of the most recent DBQ, I have labeled photos with orange arrows. This way, it will appear that I have been doing something more substantial than my usual.

The features I elected to label with orange arrows are not entirely arbitrary. When I looked at Bird B’s photos, my instant thought was “This is a loon.” Of course, that kind of bolt from the blue is insufficient to a DBQ answer, so I then took my usual next step, which is to ponder what it is about the overall Gestalt of this carcass that brought the word loon instantly to my lips. First, the sternum shaped (not labeled with an arrow.) It’s elongate, which, as Edward also pointed out, makes this not a grebe, which is the other pointy-beaked, white-under-winged group of birds one might consider for this i.d. Second, the small bit of patterning visible on the back feathers (shown with orange arrow).

Slide1
Can you make out the faint, light colored chevrons tipping the otherwise dark feathers? That’s a loon thing. What kind of loon though? We have at least some of the head to work from, though the mandibles have parted ways from the upper beak, complicating matters. Still, take a look at this helpfully labeled photo:
Slide2

Here, we can see a v-shaped white patch at the base of the upper bill. This is quite suggestive to me of a Red-throated Loon, as no other loon has such extensive white on the face, especially in the region extending up the forehead from the bill base. Without the usual hallmark of the RTLO though–the jaunty and somewhat smugly upturned look to the bill–it’s not a slam dunk i.d. As Edward pointed out, the upturned appearance of the bill of RTLO is largely due to the shape of the mandible, the upper bill being actually quite straight, as in this specimen. Alarmingly though, Edward suggested Bird B might be NOT a RTLO, but an Arctic Loon! We have never, in the history of SEANET, gotten one of those. Given this dearth, I am tempted to heed that old vet school warning about jumping to rare diagnoses: “When you hear hoofbeats, think horses, not zebras.” But then I am whipsawed by indecision when I consider all my rotations in zoos, and the memorable day I got to blow dart a zebra with its vaccinations. And then, coming out of my reverie, I remember about identifying Bird B again.

I perused the internet for some nice photos to share with you, and I found one by someone else in the world who likes to photograph rotten old carcasses! Here is a mostly skeletal Arctic Loon (known in other parts of the world as a “Black-throated Diver”:

800px-The_remains_of_a_Black-Throated_Diver_I_255618814

Photo by Miika Silfverberg via wikimedia commons

You may note that this species has what looks almost like a droopy, downturned bill: just the opposite of what we see in a RTLO. And here is a cartoon version of the birds by L. Shyamal, which gets across the main aspects of their patterning:
410px-GaviaArctica.svg

I argue that our Bird B has more white on the face than an Arctic Loon would. Add that to the extreme rarity of that latter species in our neck of the woods, and I think I am right. But I love to argue and debate, so if anyone can convince me this is something other than RTLO, bring it on!!!





DBQ answers

12 03 2015

Occasionally, I feel daunted when writing up these supposedly correct DBQ answers. Actually, most of the time I feel daunted. I am hardly an expert birder, and while my confidence in identifying our bread and butter dead bird species–loons, herring gulls, scoters–is high, when it comes to rarities, I often stumble. I was feeling additionally daunted, momentarily, by the international nature of our Bird A. Then, I very quickly remembered that we study seabirds here at SEANET, and seabirds scoff not only at international borders, but at the very idea that the Atlantic Ocean would be a barrier to their travels. For truly sea-faring birds, the Atlantic, or the polar oceans in the aggregate, are home turf, and many of their ranges are, in fact, circumpolar. Overall, the suite of species we see washing up on our beaches on the east coast tends to match what turns up on Scottish beaches, or Danish ones, better than what turns up on our west coast friends’ beaches in California or Washington. So, somewhat less daunted, I considered Bird A (which, full disclosure, came pre-identified for me by Edward, who sent the picture.)

**update: feeling MORE daunted now, after spending an hour writing up a fabulous breakdown of the identification here, and then losing it to a computer crash on my less than stellar work machine. So, here is the brief and aggravated version of the lyrical prose piece I labored over and lost:**

Bird A options: one of the jaegers, or one of the skuas. n.b., we Americans call jaegers jaegers and skuas skuas. Europeans call the whole lot skuas, which seems sensible since the four species that are candidates in a case like this are all actually in the same genus, Stercorarius. The birds we call jaegers here, specifically the pomarine and the parasitic, are both smaller, more delicate birds than the south polar and great skuas, not that one can say much about overall daintiness from this headless carcass. One thing that does leap out at me about Bird A is the tail, which is fairly short and blunt. This contrasts rather well with the longer tails of the jaegers, though juvenile jaeger tails are substantially shorter than those of their esteemed elders. Lest ye lose hope though, here’s a helpful bit of information: while juvenile jaegers do have short tails, they also have gray legs with black toes! A very dapper combination. The gray can be very extensive (see photo below of a jaeger that got a lot of attention in Texas), or run only just beyond the tarsal (“ankle”) joint, but our Bird A has no gray in evidence anywhere on the legs or feet, which appear entirely black (aside from that bit of silver jewelry its sporting).

A jaeger that caused an identification kerfuffle on Kirby Lake in Texas.

A jaeger that caused an identification kerfuffle on Kirby Lake in Texas.

So, not a jaeger then. Let us conclude that it is a skua. What kind of skua? The call generally comes down to plumage color, with South Polar Skuas being grayer, and Great Skuas browner overall, but with the dreaded exceptions, overlaps, and light and dark morphs. Terrible stuff. I can convince myself that I see some warm brown tones at the tail base and a bit along the wings, but mostly, I am persuaded by the fact that Edward sent me this picture with the note, “Great skua. Found on Texel Island, ringed in the Shetlands.” If there are field marks I am missing here that might help, please enlighten me!

Great Skua field marks. I can't get enough of these composite images. And I think that raincoat clad person is going to meet a bad end.

Great Skua field marks. I can’t get enough of these composite images. And I think that raincoat clad person is going to meet a bad end.

As for Bird B, I reserve that for the next post since I am feeling chagrined about the tragic loss of my first post, and also, I enjoy keeping Ray Bosse, who found Bird B, in suspense.





Dead Bird Quiz: Transatlantic edition

6 03 2015

It’s an international accord! Nothing brings people together like dead birds, so here are two.

Bird A’s photos were sent in by Edward Soldaat. The carcass was found on the island of Texel in the Netherlands, and since we Americans are notoriously ignorant of world geography, here is a map:

Untitled3

Bird A, mostly upper surface.

Bird A, mostly upper surface.

Another of Bird A.

Another of Bird A.

Bird B comes to us from Ray Bosse in Massachusetts. It’s a similarly degraded specimen, though Ray’s is in an impressive number of pieces.

Bird B.Tarsus and Wing chord recorded on card in photo.

Bird B.


Partly the upper surface of Bird B.

Partly the upper surface of Bird B.








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