Dead Bird Quiz answers

14 04 2014

I’m never quite certain whether I favor the DBQs that result in lively debate as to species, or the ones that end quickly in a clear and general consensus. This particular DBQ falls into that latter category, which means I feel much more confident about the accuracy of the i.d. Both Wouter and Mary Wright replied, writing that Bird A was a Little Gull and Bird B an Atlantic Puffin. Indeed, Gil Grant and Dennis Minsky who found the birds, respectively, had correctly identified them when initially found, and I am glad to get additional confirmation. Bird A, in particular, the Little Gull, is not at all common in our database. In fact, it appears to be the first of its kind reported to SEANET: so rare, in fact, it is not even included in our drop down menu of species.

Mary and Wouter are always quite good about giving us a sense of how they make their identifications, and both pointed out Bird A’s pale gray upperwing with a white border, along with a darker underwing. The overall size is important here too, as the Little Gull is quite aptly named and is dwarfed in size by our more common gulls. For me, what stood out after many, many hours looking at Herring Gull and Ring-billed Gull wings and having their image burned onto my retinas was the lack of black wingtips in this Little Gull. Its upperwing has an overall pale cast in part due to that lack of black and white contrast. The only other real contender given these characteristics might be, as Wouter suggested, Ross’s Gull, which also has a gray underwing, though not quite as dark as Bird A’s. In addition, The Ross’s Gull is a rarer find, and would be quite a sensation if found in the Carolinas.

eBird data from all years and all locations for Ross's Gull.

eBird data from all years and all locations for Ross’s Gull.

Compare with these sightings of Little Gull.

Compare with these sightings of Little Gull.

As for Bird B, the most common dark wings to be found on Cape Cod where Dennis walks are the scoters. This Bird B, however, does not fit that mold. The wings are smaller and narrower, lacking the broad shape of a duck wing. The shape overall looks alcid-like. The wing is all dark, including the underwing, which rules out murres and razorbills which both have white borders to their secondaries and a white underwing. Dovekies have a somewhat dark underwing, but lighter through the secondaries, and the overall size is smaller than Bird B as well. That leads us to the conclusion that this is an Atlantic Puffin. Also rather a rare find, with the exception of the winter of 2012-2013 when they seemed to raining down on beaches throughout the north Atlantic. Whether this Bird B died recently, or is merely a long dead and only recently found specimen, I could not say. We do know that Provincetown serves as a hook to pull in all manner of flotsam and jetsam, living and dead, organic and man-made, so who’s to say how far these stalwart wings traveled before they reached the beach? SEANET is ever good for philosophical ponderings.

An obliging puffin displays its silvery gray underwing. Photo by Boaworm, Wikimedia Commons.

An obliging puffin displays its silvery gray underwing. Photo by Boaworm, Wikimedia Commons.





Dead Bird Quiz: just wings! edition

9 04 2014

One from the north, and one from the south for you, my dear Seanetters. Bird A was found in March in North Carolina by Gil Grant. Bird B, by Dennis Minsky in Massachusetts this month. Dennis, I am also pleased to announce, has just found his 300th dead bird for SEANET! Would we were all so lucky in our searchings.

Bird A. Wing chord 24cm.

Bird A. Wing chord 24cm.

Bird A: Underside of wings.

Bird A: Underside of wings.

DMinsky6501-11177[1]

Bird B. Wing chord 14cm.

 

Bird B: underside of wings.

Bird B: underside of wings.





How many ducks is a normal amount of ducks?

2 04 2014

After independent beach walker Doug McNair raised the alarm about an increased number of White-winged Scoter carcasses on Cape Cod this winter, I felt even more drive to work up some of our data from that area. With a particular eye toward the annual counts of scoters and Common Eiders from month to month, I generated some very simple, rough and ready, back of the envelope charts for your perusal. I disclaim: I am a veterinarian and not a scientist. My capacity to analyze data is that of a commoner. Still, I find these rather interesting to look at.

By way of a bit of guidance, the y-axis here is measured in carcasses/km, which we refer to as an “encounter rate.” We know we aren’t finding every bird that washes up dead in any given month; at best, we get a snapshot. Some species turn up more commonly, and some are found more commonly when they do. Those can be two distinct issues we have to deal with. Additionally, different beaches generate different numbers of birds, which can skew things. Some of our beaches come and go from year to year as volunteers join or retire, so the year-to-year comparisons are not perfectly apples to apples in that respect either. Given those caveats, and the knowledge that there are many others, give a look at these three charts, showing encounter rates for a handful of either the most common species found (gulls, eiders, scoters) or species of particular interest given recent die-offs (alcids). Click on each chart to view a larger version.

2010_CC_encounters

2011_CC_encounters

2012_CC_encounters

An additional factor to consider is the scale involved. Some years, the encounter rates all remain low, barely exceeding 1.00 carcasses/km for any species. Other years, the encounter rate for a particular species may approach 1.6 carcasses/km (Common Eiders in 2011, for instance). So keep an eye not only on the lines themselves, and the peaks and valleys, but also the magnitude from one year to the next.
As for scoters, their general profile is that their numbers increase in winter (to be expected given their life history and migration patterns). But some winters are particularly bad for them, and others seem fairly mild. 2010 and 2011 didn’t see many, for instance, but January and February 2012 show higher numbers. Whether that’s actually a trend is far beyond the power of these very rudimentary charts to determine. But I will certainly be looking forward to seeing what 2013′s data show us for the scoters, given that we’ve gotten a handful of reports from beachwalkers and wildlife rehabbers that they do seem to be beaching more commonly of late.

So, Seanetters, tell me, have any questions about this stuff? Any sorts of data you’d particularly like to see? I’m at your service.





Sending in the reinforcements! SEANET gets help!

26 03 2014

Normally, lean, mean SEANET gets by with a skeleton crew of 2 working a total of a few hours a week. We manage to get a lot done, but some of the work does pile up. We are therefore very relieved to have help this semester. Grad student Marissa Jenko has joined us as work study and I, for one, am most grateful for the help reviewing walk data, verifying reports, and hopefully even blogging on occasion for you all. In the meantime, I’ll let Marissa introduce herself:

Lucky for us, Marissa has embraced the work with good cheer!

Lucky for us, Marissa has embraced the work with good cheer!

“Hello! My name is Marissa Jenko and I’m originally from Floral Park, NY. I received my bachelor’s degree in geology from UMass Amherst in 2011 and spent two years working at an environmental consulting firm in Somerville, MA. Though I learned a lot in those two working years, I decided I needed a change and applied for Tuft’s masters in conservation medicine (MCM) program.

Conservation medicine studies the relationships between human, animal, and environmental health and seeks to develop policies, programs, and health management practices that maintain biodiversity and protect the ecosystems that are vital to human and animal health.

Recently, I’ve found myself gravitating back towards my geology roots and have been researching the geologic reasons behind certain human and animal health issues (for example, the prevalence of iodine deficiencies are strongly correlated to the soil characteristics and bedrock composition of the region).
I became interested in SEANET after a lecture from Dr. Julie Ellis about the program. I was intrigued by the idea of using these birds as indicators of an environmental contamination event (like an oil spill) before most people are even aware that something has occurred. I’m looking forward to being a part of the team!
In my spare time I’m an avid skier, crafter (particularly sewing), and reader.”





Take a summer course at Shoals Marine Lab!

19 03 2014
Not a bad looking campus, huh?

Not a bad looking campus, huh?

At this point, readers, I am no longer asking, I am telling you and those you love to take a course at Shoals Marine Lab! Yesterday, marked the close of the application period for the one week research assistantship helping us with gull banding, but there is still time to register for one (or more) of the many amazing courses SML is offering this summer. I want to make a particular plug for two courses: Field Ornithology is in grave peril and will be canceled if the minimum enrollment is not met. The course, run by my friend David Bonter, is a fabulous opportunity to learn about birds and their ecology while in their very midst. I cannot fathom why that course is not at maximum enrollment, so let’s get it there!

I have a couple of my own students at North Shore Community College interested in Field Animal Behavior, another course in need of more students. Check that one out and the rest of the summer course catalog, or pass this information along to anyone you know who might be interested. High school students, college students of all stripes, and life-long learners are all welcome. If the sticker price has you balking, rest assured that generous financial aid (in the form of scholarship) is available, and you need only enter some simple information from your FAFSA in order to apply.

I maintain that no New Englander should live her lifetime here without ever at least visiting the Shoals. Why not immerse yourself entirely (and this is likely to be both a literal and figurative proposition) in our Gulf of Maine ecosystem?





The decimation of ducks

4 03 2014
A sampler pack of scoter wings mostly with attached sternae found in Brewster MA. (photo: Diana Gaumond).

A sampler pack of scoter wings mostly with attached sternae found in Brewster MA. (photo: Diana Gaumond).

Winter is a grand time for viewing sea ducks near shore. Along my SEANET route, I routinely see bufflehead, common eider, scaup, common goldeneye, red-breasted merganser, and a handful of other occasional visitors. Not surprising then, that winter is also the time that we see the peak of duck mortality along the beaches as well. This winter, it looks like we may be seeing an uptick above typuical mortality among white-winged scoters (WWSC) on Cape Cod in particular. A quick glance at our numbers shows somewhere between double and triple the number of WWSC we saw last winter on SEANET beaches (though that number was never very large itself–fewer than a dozen.) Outside SEANET surveys, we have also been getting reports from Doug McNair, who surveys the outer Cape independently, that WWSC mortality seems well above normal.

Rare intact WWSC found by Warren Mumford in Chatham, MA.

Rare intact WWSC found by Warren Mumford in Chatham, MA.

One thing we tend to notice in duck carcasses is their incomplete nature. While other birds are often found intact, most duck species seem to be found in pieces. Doug raised the question of whether this might be anthropogenic; perhaps hunters strip off the breast meat and toss away the rest of the carcass? I can’t know for sure, but having looked at many pictures of carcasses in various states of disarray, it seems, to my mind, more likely that ducks turn up well scavenged in the average way, but that perhaps ducks are tastier than other carcasses?

And here we see a scoter head, spinal column and foot striking out on their own. (Photo by Jack Hooper).

And here we see a scoter head and neck striking out on their own. (Photo by Jack Hooper).

[I don't have a clear answer on this, but in tracking individual carcasses over time on SEANET beaches, there does tend to be a typical pattern to their gradual dissipation. First, the entrails are dug out (typical gull behavior, that). Then, the pectoral muscles are stripped from the sternum. As the carcass further decomposes, the wings tend to stay with the sternu, the head goes off with the neck vertebrae, and the ribs, united with the lower vertebrae and fused pelvis eventually drop the legs and roll off by themselves. Given enough time, it appears, all carcasses (or most, anyway) will weather down to the most durable parts: bon, and the strong primary flight feathers that anchor into the bone.  This is merely my personal observation at this point, but it does give me yet another little project to delve into when time permits. I welcome your thoughts on what organisms are doing this stripping away of the meat. On my beach, I suspect the gulls. On southern beaches, I ave been impressed with the diligent scavenging of the ghost crabs. But people may be involved in certain cases too. Have any observations, Seanetters and other beach enthusiasts?





Dead Bird Quiz answers

26 02 2014

Let’s delve into these, shall we? Bird A, I was very relieved to find, retained a tell-tale characteristic that vastly simplified this i.d.: the feet. The lobed toes with no webs between mark this bird as a grebe. What sort of grebe though? Here on the East Coast, we get three species turning up with some regularity: Pied-billed, Red-necked, and Horned. The feet won’t give us much by which to differentiate those three, so we must turn to other features. Wouter weighed in on this one, noting “It is medium sized with dark axillary feathers. Therefore, I think it’s Red-necked Grebe.” Wouter is basically never wrong, so let’s look at those aspects of this bird that he’s focusing on. The wing chord, making a guesstimate from the ruler in the photo, is somewhere around 16-17cm. The range for Horned Grebes is typically 13-15, and Pied-billeds smaller still at 11-14cm. Our Bird A is somewhat in between the range for Red-necked Grebe (at 18-21cm) and the smaller Horned Grebe. So, how can we make this call? As Wouter points out, the axillaries (or wing pit feathers) are dark in our Bird A. I have been staring at images of Horned Grebe and Red-necked Grebe underwings at the Slater Museum’s wing website, and am frustrated by a fair bit of overlap in their appearance; both species have darker feathers at the wing pit, variably with age and sex, it appears. Add to that that the specimen we have in Bird A looks to potentially have some twisted feathers near the wing pit where the orange tag is attached, so it’s possible that we are looking at the upper surface of those feathers rather than the under. The only other consideration I have here is the foot color. I don’t find a lot of definitive coverage of this, but in my experience, Horned Grebe feet are a paler gray than Red-necked Grebe feet, which makes me lean toward Horned Grebe for this specimen. On the other hand, the primaries look darkish gray, which tends to weigh more on the Red-necked side of the scale, as Horned Grebes tend to have a very white underwing overall. Persuade me, Wouter and any other Red-necked Grebe proponents!

Horned Grebe underwing

Horned Grebe underwing

Red-necked Grebe

Red-necked Grebe

Bird B takes the challenge of the Dead Bird Quiz to yet another dizzying height. This set of wings is in rough shape, but what we can tell is that they’re quite small, there appears to be a pale lengthwise band running along the upper surface, and there is a substantial amount of white on the underwing, particularly through the secondaries. I thought it might be some sort of shorebird, and Wouter did even better, going so far as to say it’s likely either a Semipalmated or a Wilson’s Plover. We don’t get many shorebirds in our SEANET database, so my experience identifying them is limited. These two species are quite similar, however, as detailed in a previous post, and in that case, we had additional parts to judge by–like feet. And heads. So perhaps with this one, we’ll go with “Unknown Plover.”

Forster's Tern in winter plumage (photo: BRian Gratwicke)

Forster’s Tern in winter plumage (photo: BRian Gratwicke)

Bird C will be a cinch for our southern contingent, but I include it because they’re still novel for me. It’s a tern, to be sure, and when confronted with terns, I often sigh and go take a coffee break. But this one is intact, so I actually stand a chance. Bird C has an faint orange tinge to an otherwise black bill, and some black on the head. From one angle, it looks more like a partial black cap with a white forehead, but from the other angle, it looks more like a black eye patch. That feature is what I latched onto, guessing that this is a Forster’s Tern (which is also what Janet Kurz, the finder, identified it as.) Wouter also concurred, citing additionally the white tail edges and light inner primaries to help clinch it. I like this bird for the DBQ especially because the dishevelment of the feathers over the head change the bird’s appearance substantially. This is a challenge we dead bird enthusiasts are accustomed to–plumage that makes the i.d. in a live bird may be substantially altered or even absent in a carcass. Luckily, there were plenty of other aspects of this bird that we could utilize. And I’m glad we all agree on at least one of these!








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