Update on eider research

30 10 2014

It’s fall, and on Cape Cod, that often means piles of dead eiders rather than piles of rustling leaves. In the multi-year investigation into why so many common eiders turn up dead around Wellfleet most years, the USDA, USFWS and numerous other groups have partnered up and pooled their skill and resources to try to get to the bottom of what’s happening. Right now, the researchers are wrapping up the live bird sampling phase of this fall’s work; they have been trapping birds as they arrive from their breeding islands–some from as nearby as Boston Harbor, some from nearer the Arctic. The idea is to sample their blood and feces to see if they arrive in Cape Cod Bay already having been exposed to, and possibly even shedding the virus. The birds are also banded so that if they ultimately die (of any cause) and are found, we will know what their viral status was as of the beginning of the overwintering season. The Cape Cod Times has posted an article with some rather delightful photos of this work.

Cape Cod is a SEANET hotspot, luckily for us, and many of our dedicated volunteers have offered to help in any way they can. Up to now, biologists were interested in hearing where and when eiders were arriving from the north. With the sampling work completed, the focus will now shift to documenting and collecting dead birds. Anyone, Seanetter or not, can help with this effort, so if you see more than a few sick or dead eiders (and this is not just for Cape Cod), please contact Randall Mickley (randall.m.mickley”at”aphis.usda.gov or 413-658-7113).

The other critical thing to report is any banded bird found dead. Here is a timely time to reissue our dead bird flyer! Please encourage all your friends and neighbors to jot down any band numbers they find and report them. I can’t emphasize enough how valuable those data are!

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Dead Bird Quiz answers

28 10 2014

Before I launch into the DBQ answers, it’s time to revisit an old quiz. Edward wrote in to say that our conclusion on a bird we featured a while back in this DBQ may have been erroneous. He writes that the bird more closely resembles a Brown Booby than the juvenile cormorant we deemed it to be. Edward is right in pointing out that that species is hardly unheard of off the South Carolina coast, so I wanted to bring the debate to your attention and see what you think upon considering this idea.

Now to the current quiz. There was no debate on this one; Bird A was universally recognized as a Northern Fulmar (NOFU), and Bird B as a Mute Swan. Indeed, this one was not intended to be very tricky, but more to pull out a couple species we see dead only rarely on SEANET beaches. The reasons for that most likely do not reflect the overall commonness of each species. The Mute Swan, in particular, is a non-native species that has risen to nuisance status in many regions on the United States, and we have several volunteers who report dozens of live swans every time they survey their beaches. Yet, we don’t get them reported dead very often. In fact, the last time we had a Mute Swan reported was back in 2011 in Rhode Island. Whenever a bird is uncommon in our database, we wonder why. Is the species rare overall? Is it found so far offshore that a carcass is unlikely to wash up on a beach? Do the birds go elsewhere when sick or dying (like a sheltered bay or estuary, rather than the open water near a SEANET beach)? I don’t know the answer in the case of Mute Swans. But at least making the i.d. is simple–a very large (see index card in photo for reference), all white bird with an exceedingly long neck. I suppose egrets partly meet that list of characteristics, but they are far less massive and they have long legs with unwebbed feet: far different from our Bird B. In Bird B, we have the additional benefit of an intact skull. Edward pointed out that the skull shows the knobby projection at the base of the bill that marks the Mute Swan. Compare the bill profiles of Mute Swans with two native North American swan species:

Image: NC Wildlife

Bird A, the Northern Fulmar, is another species that has not turned up on a SEANET beach since 2011 when Frank Kenny found on in New Jersey. Here is a side-by-side of that bird and Sarah Porter’s find:

NOFU in NJ (Photo: F. Kenny)

NOFU in NJ (Photo: F. Kenny)

NOFU in MA (Photo: Sarah Porter)

NOFU in MA (Photo: Sarah Porter)

In both cases, after the initial glance that often makes one think of a gull, closer inspection reveals the thick, stocky bill that makes both these birds unmistakably Northern Fulmars. What is interesting is the substantial difference in plumage coloration. Frank’s NOFU is almost white overall, while Sarah’s is a mix of grays and some interspersed brown feathers over the mantle and upper wing. What’s going on there? The answer is twofold.

First off, what’s with the light bird and the dark bird? Are they different subspecies? Different sexes? It’s a bit complicated, so let’s start with the basics.

Northern Fulmars are aptly named on both counts. “Fulmar” derives from “foul gull” (and I know many will argue that gulls are foul enough) due to their charming habit of projectile regurgitating stomach oils as a defense. The “northern” refers to their range. The species is circumpolar and nests from the high Arctic down as far south as Newfoundland and France in the Atlantic and the Aleutians in the Pacific. They winter from the limit of the pack ice down to the mid-Atlantic states and sometimes occur as far as Florida or even (very rarely) Mexico. Given this, it is not unusual to have NOFU anywhere along the SEANET territory during the non-breeding season, approximately September through April. After that, they mostly head north to breed, though in some years substantial numbers persist as far south as North Carolina as late as May or June.

The species is divided into two subspecies: Pacific (Fulmarus glacialis rodgersii) and Atlantic (P.g. glacialis). Our Atlantic subspecies is larger overall, though within the subspecies, the high Arctic breeders are smaller than birds breeding in boreal regions (farther south). Also within the Atlantic subspecies, there are what we call two “morphs” or color varieties: light and dark. That gets us to the main difference between Sarah’s NOFU and Frank’s. In the Atlantic, the light morph is more common, except for a few pockets in the high Arctic where the dark morph prevails. Even though Sarah and Frank’s birds look rather different in their coloration, both of these would be classified as light morphs since both have all white bellies, breasts and heads. This gives the birds a coloration pattern similar to a Herring Gull overall.

Light morphs nesting in Scotland (Photo by Dick Daniels)

Light morphs nesting in Scotland (Photo by Dick Daniels)

Dark morphs are harder to find in the Atlantic, so most pictures of them come from the Pacific where they are more common, but do check out these photos at neseabirds.com to see some very nice comparisons between the two.

Finally, that gray/brown mottling on Sarah’s bird. That is evidence of molting going on in this bird, where new feathers are coming in amongst the old. Edward points out that that makes this a bird older than 1 year since it is now replacing those older, worn feathers.





Dead Bird Quiz: Sarah Porter edition

24 10 2014

First off, the SEANET data entry site is back online! Huzzah! Thank you all for your patience; you should be all set now to enter surveys again. Let’s celebrate with a Dead Bird Quiz.

 

Both these birds were found by volunteer Sarah Porter in April in Massachusetts. What do you think everyone?

Bird A:
SPorter6528-11193
SPorter6529-11193
Bird B:
SPorter6548-12178 SPorter6549-12178





Data entry portal is down!

22 10 2014

Many of you have found your attempts to enter your surveys online stymied in the past week or so. I have also noticed this, and it appears that something is amiss with the server that usually dishes up our website. I am trying to track down the problem and have it remedied, but until I do, please be patient and also be assured that it’s not your fault–the error appears to be at the source.

To distract you from that though, I have the good news that my basement now hosts 720 copies of the Field Guide to Beached Birds of the Southeastern U.S! Most of these will be distributed to biologists for official use, but we should have enough to get out to any interested Seanetters too. More details to follow!





Arctic seabirds sound their warning; who’s listening?

9 10 2014

This past weekend, New Hampshire Public Radio, my preferred news venue, wrapped up their fall fund drive. I listen even during the drive, possibly out of a self-flagellating penance for not actually donating. There’s something satisying about the guilt. During the fund drive, the announcers were pushing their drawing for a free trip to Costa Rica. “Unbelievable! The biodiversity is higher than anyplace else on Earth!” You’ll get no argument from me on the merits of a Costa Rican getaway, nor on the diversity of species to be found there. But for certain species groups, the highest biodiversity comes not down near the tropics, but near the poles.

I’ve just been reading a report on Arctic seabirds from the Conservation of Arctic Flora and Fauna (CAFF) group. In it, the authors point out that the cold (though ever warming) waters of the northern oceans have historically been a nutrient bonanza on which these birds can rear their young. Now though, the convergence of the mutliple evils we’ve managed to work on our oceans appear to affecting many of these species quite profoundly.

Seabird populations are challenging to study and count. Aside from the breeding season when they come onto land, many of these long distance seafarers lead a nomadic existence and pinning down their numbers is difficult. For some species, we don’t have reliable census data even for the breeding colonies, or, if we do, only for the past few decades or so. These limitations make it hard to pick up on anything but catastrophic population crashes.

What researchers are finding now, is a disconcerting emptiness on many of the colonies. In Iceland, historically a hotbed for seabird breeding, scientists now find empty puffin burrows, eggs or dead chicks rotting in abandoned tern nests, and entire swathes of islands devoid of much bird life at all for several years running. Seabirds tend to long lives, and one or two bad breeding seasons are easily borne. But as more and more years like this pass, where the adults either return to the colony and fail to rear any chicks, or simply don’t attempt to breed at all, the consequences for the future grow more grim. These adults will continue to age and will ultimately die, even if they live 30 or 40 years before that happens. If there have been no young birds coming up to take their places, the results are clear. What still isn’t clear is why these breeding collapses are occurring. The CAFF report points to changes in sea ice, altered prey distributions, and increasing frequency of extreme weather events as possible players. A 100 year storm, after all, can wipe out many adults in a breeding population. When those 100 year storms are coming every four or five years…a population only has so much resilience.
We do know that seabirds will respond to prey availability changes by altering their foraging behavior. This graph depicts the type of prey brought back to the nest by thick-billed murres. Looking at the blue and yellow sections of each bar, we see the shift beginning in the 1990’s from the ice-associated polar cod to capelin as ice breakup came earlier and earlier in the season.

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Whether or not an alternative prey is equally appropriate for rearing nestlings varies with the prey. Such shifts seem to coincide with decreases in chick survival in some species, so it does appear that one fish is not necessarily as good as another.

Pollutants in the foraging waters and in the prey are still an issue, with mercury levels in some seabirds high enough to affect breeding success, and persistent organic compounds like flame retardants and pesticides in eggs at concentrations high enough to make them unfit for human harvest and consumption. Some researchers even point out that warming oceans boost the metabolisms of the fish swimming in them, which could make them able to swim just a bit faster and evade their avian pursuers. For birds already on the thinnest of margins of survival, even an effect so slight would be piling on their troubles.

One thing is perfectly clear in reading through all these reports and into the research itself; while empty-headed commentators on the pretend news try to drum up paranoia and conspiracy theories about the existence of climate change, the scientists are keeping their heads down, scanning for the few eggs or chicks still viable, certain in the knowledge that climate change is wreaking havoc already, and we may be watching these birds disappear.





A followup, and a flyer

1 10 2014

Edward Soldaat wrote in on the last post to add some more useful notes on making the cormorant identification in last week’s Dead Bird Quiz. I didn’t want to just leave those buried as a comment, so I am pulling them up and featuring them here, front and center. Edward knows vastly more than I about skulls, so I present his comments as given:

“In addition: another important feature to distinguish cormorants from shearwaters or gulls is the absence of the depressions for the salt glands above the eyes. In this case skull and bill were too big for any shearwater, only a giant Cory’s Shearwater would have come close. But in smaller cormorants the lacking of visible nostrils and salt gland depressions are important characteristics. Interesting is also that cormorants and darters (not in gannets, pelicans or other) have a small dagger shaped bone connected to the back of the cranium, embedded in the strong musculature of the neck: the occipital style.”

The salt glands are organs you may have seen in action in living birds like gulls, which will occasionally tilt their beaks down as a clear liquid runs down from their nares. These are secretions from the glands, which function almost like an accessory set of kidneys, cleaning salts from the blood and allowing seabirds to drink saltwater and compensate for their actual kidneys’ comparative (to mammals) lack of ability to produce concentrated wastes.

The second item for your persual today is a flyer I worked up to address the many questions that nature centers, town officials, and biologists get from the public about birds sporting metal tags or orange cable ties. If you walk a beach for us, and know of an information board, a nature center, community center, public library or other spot where people might see one of these, would you consider printing and posting one for us? We might gain some new recruits, or, at the very least, alleviate some confusion among beach goers not in the know.





Dead Bird Quiz answers

26 09 2014

Another set of unanimous decisions on these three specimens. Edward and James both came back with answers of A) cormorant (probably double-crested); B) Juvenile herring gull; C) no idea/?

That’s where I came down on these as well, but I wanted to post them because they each illustrate one of the challenges in identifying dead birds, even when the carcass is lovely and intact, as in Bird B.

For Bird A, we mainly have the skull, and thus the bill, to go on. The bill is thin, but has a substantial curve, and a prominent hook at the tip. Cormorant does immediately come to mind given these features, but I always try to think “What else could this possibly be?” For Bird A, the only other species group that seemed even remotely possible was the shearwaters. Their bills can have a similar curve and hook. “But wait!” I hear you shriek, “Shearwaters are tubenoses, and I don’t see any tubes on top of that bill!” Well I don’t either, but we must always contend with the possibility that decomposition and general falling apart can alter features rather profoundly. Bird A has lost the keratin sheath that overlies the bones of the bill during life. That sheath sloughs off rather readily as the carcass weathers, and if the tubes on the noses of the tubenoses were only a feature of the bill sheath, and not the underlying bone, then we might indeed see a skull that looks like this.

This image of the skulls of both an extinct (top) and extant species of shearwater from a paper by Ramirez et al shows the general features of shearwater skulls when the bill sheath is no longer present.

extinct Lava shearwater skull (top) and Manx shearwater skull. (from Ramirez et al, 2010.)

extinct Lava shearwater skull (top) and Manx shearwater skull. (from Ramirez et al, 2010.)

In these images, you can see that the overall curve of the bill is not as great as in our Bird A, and you can see distinct nares (nostrils) atop the bill, though the distinctive tube structures are indeed, far less evident without the sheath in place. Cormorants, on the other hand, have a rather different looking skull:

cormorant_sideview

Note the lack of evident nares in this cormorant skull. (Photo: Dominique Harre-Rogers, copyright Smithsonian Institution)

In this photo from the Smithsonian Institution, it’s clear that there is no rise in the bone at the level of the nares as there is in the shearwaters. In fact, it’s hard to really see the nares all that much at all here. This is a feature of pouchbills like cormorants and gannets; in fact, they lack external nares entirely. We who handle the birds live must always pay attention to how we restrain the bill since, if we hold the bill closed entirely, the bird has no way to breathe.

All this explanation is really just to tell you what you all apparently already knew: Bird A is a cormorant. It’s difficult to say which species, since an accurate culmen length relies on the bill sheath being intact and seeing where it meets the feathers or facial skin. Not possible here, for obvious reasons. Based on their ubiquity, and the overall shape of the skull, Double-crested is the more likely.

Bird B was beautifully intact, so it may seem strange that I used it here as a challenge. But there were features on this carcass that I think could throw some people off. Everyone concurs that this is a juvenile Herring Gull. mlyons6759-15258-1Indeed, there are many features that would lead us there: the overall gray over the belly and underwings are characteristics of young Herring Gulls that differ from Great Black-backed, Ring-billed, and Laughing Gulls, the three most likely alternatives. So why not just call this a Herring Gull and move on? The color of the legs and the color of the mantle (the back between the wings) caught my eye in this bird. The legs look reddish to me, which makes me think of Laughing Gulls as they have reddish black legs as adults. Our Bird B also has quite a distinct brown pattern to the mantle, where most of the juvenile Herring Gulls we see have more of a grayish wash. The Larusology blog does a good job helping people identify gulls, and this post about Herring vs. Thayer’s gulls points out that this phase is a normal one in young gulls–the feathers over the mantle are large and have a scaled appearance, while the wings have a smaller pattern that looks more checkered, very much like our Bird B.

Overall, the weight of the evidence falls on the side of Herring Gull, especially the conspicuous features like the color of the rump at the tail base. In young Herring Gulls, this is dark, where in Laughing Gulls, Ring-billed and Black-backeds, it’s white. None of those species have this much gray and brown over the entire breast, belly, and under the tail. So we’re left with that strange reddish color to the legs. My only guess is that they usual pinkish color has been altered by some trick of the light in combination with the effects of desiccation. In any case, this bird didn’t fool anyone, apparently, and really only had me wondering what was up with it. I’m always hoping to find some weird gull hybrid too, so maybe I see oddities where they are not actually present.

Finally, for Bird C, I agree with our respondents: no way to tell from what we have, which is a rather shredded wing missing a bunch of its coverts. “Unknown bird” it is. You can’t win ‘em all.








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