Empty nests

11 09 2015
Songbird bander Lindsay Herlihy helps my elder son release a cedar waxwing!

Songbird bander Lindsay Herlihy helps my elder son release a cedar waxwing!

This week, I went back to school, meeting several classrooms’ worth of new students. The campus, which had been a veritable ghost town, is now bustling again with bewildered and lost students, nervous students, and the feeling of optimism that comes with a new school year no matter how old you may be. Over the summer, I was focused on SEANET, and on spending time with my kids, and on the gull project on Appledore Island. For the first time, I combined those last two and brought my two sons out to Shoals Marine Lab for a meeting with the Director there, Jennifer Seavey. I’ve been out for gull banding just about every year since 2008, but I had never visited the island when the gulls were not breeding. It was a strange feeling, then, to encounter gulls loafing about near their tousled old nests, not trying to dive bomb or defecate on me. It was quiet and weirdly calm. The breeding birds were slowly departing, and the young almost all fledged and gone too. Lovely as it was, I couldn’t help but feel like the soul of the island was missing, not only because the gulls were going, but because there were no boisterous undergrads running around, working on projects, mucking around in tide pools,  or lying in the hammocks during downtime from classes. I won’t deny, it was pleasant to see this quiet side of Appledore, but it was undeniably strange to see all those abandoned grass nests where before I’d been chased off by individual gulls that I’ve known for years.

Broken eggs litter the ground on Seahorse Key. (Photo: AP)

Broken eggs litter the ground on Seahorse Key. (Photo: AP)

It got me thinking about another island with a whole lot of empty nests. Shoals Director Jenn Seavey previously worked on Seahorse Key in Florida. On that very island this year, thousands of waterbirds in the middle of the breeding season, disappeared. Many left eggs behind in their nests. Researchers say the birds were there on the 19th of May, and all gone when they checked again on the 21st. Was it a predator? Someone flying a recreational drone over the island? Hypotheses abound, but whatever it was, the disturbance had to have been profound to cause such extensive abandonment. Biologists found only a fraction of the birds from Seahorse had re-nested on other islands. The rest seem to have lit off for parts unknown. Whether they will come back next year is unknown. We will be in suspense until the breeding season rolls around again next spring.

Back on Appledore, we were also focused on filling up an island next summer. My colleague at Northern Essex Community College, Ken Thomas, and I, were meeting with Jenn Seavey and Julie Ellis about expanding opportunities for NECC students to take courses through the lab, and also potentially to help out with the gull project beyond the banding weeks in May and July. I came away from the meeting with a long list of people to see and things to do, and money to find, but I am optimistic that we will see community college students on the course rosters on the island next summer.





These shearwaters ain’t foolin’ nobody!

1 09 2015
These GRSH show off their competitive natures and their field marks. The birds in the background look like Wilson's Storm Petrels to me. (Photo: DickDaniels via wikimedia commons)

These GRSH show off their competitive natures and their field marks. The birds in the background look like Wilson’s Storm Petrels to me. (Photo: DickDaniels via wikimedia commons)

As anticipated, pro dead bird identifiers like the readers of this blog recognized the three species in the last post immediately. Bird A is a Greater, Bird B a Sooty, and Bird C a Cory’s Shearwater. Luckily for me, shearwater i.d. tends to be straightforward, and I have a few quick features I look for to make the call at a glance. For the Cory’s, it’s that yellow bill. As the field guides say, that is “distinctive” once you’ve established you’re looking at a shearwater. And the wacky tube nose is a giveaway on that. For the Sooty, the dark breast and belly are the decisive factor here; other shearwaters have white on the underside. The most common shearwater we get on SEANET beaches though is by far the Greater. When looking at a light bellied shearwater with a dark bill, it’s almost always a Greater. But I check every time for what I find the most reliable indicators. GRSH have a dark, smudgy patch on the belly. To the uninitiated, it can look like dirt, or even oil. You all, of course, are initiated, and know that. That is, however, why I chose Bird A particularly. The smudge is variable between individuals, and I found it interesting that it is basically absent in this bird. That did give me pause, so I double-checked with another of my go-t0s for GRSH, the undertail coverts (dark in Bird A). Among the white-bellied shearwaters, the Manx has white undertail coverts, while both the GRSH and Audubon’s have dark. So we should at least entertain Audubon’s when looking at a shearwater that has a white belly and seems to lack any dark smudging.

Though I didn’t provide a picture of the upper side of Bird A in the original post (not that any of you needed it), so I will do so now:

Other side of Bird A. Photo courtesy of L. Ries.

Other side of Bird A. Photo courtesy of L. Ries.

This Bird looks brownish overall on its upper surface. This is definitely a GRSH characteristic; Audubon’s shearwaters are much blacker above. Finally, if you look at the upper surface of the tail, you can see a disheveled pale band in evidence. This is also a GRSH feature; Audubon’s have an all dark rump and tail. The pale tail band also brings up one last species to keep in the back of our mind, though it very rarely turns up; the Black-capped Petrel is not a shearwater at all, but it is a tubenose with a white belly and dark upper side. What sets it apart, however, is a broad, clearly white band on the upper tail, and a sharp black band on the underside of the wing. I am always hoping such rarities will turn up, so I try to keep my mind open to them, and my oddball i.d. skills honed.





Update on shearwater mortalities

26 08 2015

Reports of dead shearwaters continue to come in from both Seanetters and non-SEANET affiliated folks. All summer, this has been a decidedly northern phenomenon; of the 16 Greater Shearwaters reported to SEANET, three were found in North Carolina, and all the rest were spotted between Long Island and Provincetown at the tip of Cape Cod. We have also received word of dead shearwaters from National Parks Service personnel, wildlife rehabilitators, and members of the public. We even had a shearwater banded in Spain (!) turn up dead on a beach in Winthrop, Massachusetts. Thanks to Susannah Corona for that report, and I will share with you the history on that bird when I hear back from the European banding lab.

I had planned to post a Dead Bird Quiz today, so I will throw in a shearwater themed one amidst this post. Easy peasy for you Dead Bird Identifiers extraordinaire, but humor me.

What kind is this? (Found on Long Island)

What kind is this? (Found on Long Island)

And this one? (Found by J. Powell in NC)

And this one? (Found by J. Powell in NC)

How's about this guy? (Found by T. Lee, brand new volunteer in NC!)

How’s about this guy? (Found by T. Lee, brand new volunteer in NC!)

We know that summer shearwater mortality is a fairly typical phenomenon, though the magnitude does vary year to year. Last year was extremely quiet on the shearwater front, with only four reported to SEANET, and nothing that raised anyone’s eyebrows outside SEANET either. This year is rather a different situation. Fifteen Greater Shearwaters were found on beaches in Eastham, Massachusetts alone, with perhaps a total of another dozen birds found on various other beaches on the ocean side of Cape Cod. Several agencies and non-profits have collected carcasses, so we may have some necropsy results by fall. If nothing else, we can get a glimpse into the general body condition and stomach contents of these birds.

In some of the back and forth on email amongst wildlife biologists, veterinarians, rehabbers and seabird researchers, this request was put forward by Kevin Powers: “I would recommend that the napes of the necks of any Great Shearwater cadavers be photographed because there is some limited ability to age birds to their 3rd year based on the amount of brown feathers on the nape using Peter Pyle’s Handbook to North American Birds (Vol 2). I would be more than willing to participate.” Any of you who find these birds, whether on a SEANET walk, or just while out and about, please do consider taking a photo as Kevin described. It could get us a little closer toward understanding the demographics (zoographics?) of this die-off.





Here are the shearwaters you ordered.

16 07 2015

In June, messages like this one began pinging around on the bird lists:

“There is increasing evidence of a die-off of Great Shearwaters along the Atlantic Coast of the Bahamas. Most of the information comes from Abaco where there is a long coastline and several active birders. I would be interested in learning if other locations in the Eastern Caribbean and southeastern US are experiencing similar die-offs.The shearwater die-off is a phenomenon that happens every five to ten years. In the Bahamas it lasy occurred in 2007. According to the late Dave Lee these are young Great Shearwaters migrating from their natal home in the South Atlantic to their feeding grounds off the US and Canada, The combination of poor food supply and wind conditions in the doldrums that make the passage unusually strenuous leads to the birds expending all their energy and expiring. It is a normal event for this species and has been recorded many times.” –Tony White

Brand new Seanetter Tonya Lee found a GRSH on her inaugural walk in NC!

Brand new Seanetter Tonya Lee found a GRSH on her inaugural walk in NC!

Indeed, it is normal, but as you can see from this note, it is not consistent in magnitude from year to year. On SEANET beaches, we start seeing Great Shearwaters on our southern beaches in June, and by July, Seanetters are finding them all the way up through Massachusetts. Though the birds turn up every year, their numbers vary. This summer does appear to be a bigger year, though not by much based on our data alone. Last summer, we had a total of seven carcasses across all beaches. As of today, we’ve had ten reported, though numbers of GRSH always taper off by the end of July, so I don’t expect to see many more. In 2013, we had only three GRSH turn up. Which of these is “normal?” I don’t know.

The National Parks Service SEANET team on Fire Island have found quite a few this year.

The National Parks Service SEANET team on Fire Island have found quite a few this year.

I was honored to contribute a bit to a paper on the subject that mentions all the complicating factors–are we just looking harder now than we used to? Possibly, though at least over the past few years, SEANET data has been consistent. We will have to see if any long term trends emerge over the next ten years of Seanetting, but right now, it looks like shearwaters have good years and bad years, mainly hinging on the weather. There are always the marginal individuals that, in a good year, may eke out a living, and in a bad year not.

Occasional other species of shearwater, like this sooty, also turn up. (photo: NPS)

Occasional other species of shearwater, like this sooty, also turn up. (photo: NPS)





Avian Flu and You

9 06 2015

I have been remiss in not writing about the avian influenza outbreak currently going on among domestic poultry in the United States. Seanetter/physician Donna Cooper wrote to me on the subject of keeping you volunteers protected during your dealings with carcasses, and her prompt is much appreciated. Here is a bit of a primer on what’s been going on, and what precautions you ought to take.

Avian flu appears and recedes in the news all the time, so it can be difficult to know when big flu news is breaking. The current out break is most assuredly newsworthy, with millions of birds out west being culled in the face of the disease’s potential spread. Referring to a monolithic “avian flu” is misleading however. There are many sorts of bird flu, some causing little to no illness and spreading almost undetected in a bird population, and others causing massive and widespread mortality. The two main divisions used to categorize avian flu are LPAI (low pathogenicity avian influenza) and HPAI (high pathogenicity avian influenza). Seems fairly straightforward; LPAI=mild, HPAI=severe. Alas, it is not so simple as that. LPAI vs. HPAI refers only to the disease’s behavior in chickens in a laboratory setting. If an avian flu makes chickens very sick in a lab, it’s HPAI. If it causes no clinical signs or mild ones, it’s LPAI. This tells us nothing about how the disease would affect geese, ducks, other waterbirds, or even seals or humans, for that matter, and in fact, the same disease can profoundly afflict one species, which causing no perceptible issues in another.

(Left to right): Dr. Catherine Woteki, Dr. Fidelis (Fidel) Hegngi,  and Dr. Denise Brinson visit a backyard coop. These small operations are now on the frontline of disease monitoring and control. (photo: USDA APHIS)

(Left to right): USDA and APHIS scientists Dr. Catherine Woteki, Dr. Fidelis Hegngi, and Dr. Denise Brinson visit a backyard coop. These small operations are now on the frontline of disease monitoring and control. (photo: USDA APHIS)

Beyond the HPAI/LPAI division, we have the further H/N classification. You may have heard of the H5N1 bird flu causing fatalities in Indonesia and other countries a few years ago, or the H1N1 “swine flu” that laid many of us low in the epidemic of 2009. These Hs and Ns refer to proteins present on the virus’ surface that determine, in part, its behavior–how it gets into the body, how it invades cells once there, how severe its effects may be. Generally, though this is an oversimplification, the H5 class of avian flu are bad news and worth watching. These H5 viruses are exactly what government labs found when they tested wild birds found dead in the Pacific Northwest back in December. H5N2 and H5N8 were detected in a wild duck and a captive raptor, respectively. Virologists work to try and understand the family trees of viruses, and their work on these strains indicated that these viruses may be related to avian flu viruses previously identified in Europe and Asia, but to complicate matters, an H5N1 virus found in a wild duck in the U.S. in January of this year does not appear related to the H5N1s that have caused human mortality in Asia. This latter virus is what is known as “mixed-origin,” reflecting flu viruses’ general gift for mixing and matching genetic material when they encounter each other. That ability to “re-assort” and splice together bits of one variant with parts of another is part of what keeps us all vigilant about flu. If something like the Asian H5N1 bird flu, which presently can pass from birds to humans but so far has not been able to jump effectively between people, managed to acquire that skill, we would have the makings of a pandemic.

So, what of the goings-on in chicken houses throughout much of the country? LPAI infections have occurred from time to time in domestic poultry in the U.S. These strains are known to circulate in wild waterfowl in the U.S. True to their LP designation, these outbreaks may infect many chickens quickly, but cause only mild disease. HPAI in a poultry house, on the other hand, can be devastating. This year, H5 HPAI has been detected in backyard and commercial poultry, as well as in wild, migratory birds. You can see the latest numbers at USDA APHIS’ tracking site. The scale of the problem becomes apparent when you note the flock size listed in the far right column at that site–some of these chicken operations are raising over a million birds. Complete depopulation of these chicken houses after confirmation of HPAI infection is a daunting, though not unprecedented prospect. An outbreak of Exotic Newcastle Disease in poultry in 2002-03, for example, resulted in the euthanasia of over four million birds in the U.S. The numbers involved in the current HPAI outbreak are, admittedly, far higher and losses are ongoing.

Captive poultry are comparatively easy to control when we compare them with wild birds, however. We know that avian flu of various strains circulate in wild birds who can spread them throughout their migratory range. Waterfowl appear to be the major purveyors of the viruses, and can travel great distances. It may seem strange that a disease that so rapidly sickens and kills chickens and turkeys could be spread by wild birds apparently hale and hearty enough to fly the length of a continent. Part of the explanation lies back in the fact that not all birds are affected by avian flu the same way. HPAIs are “high path” in chickens, but the same virus often causes no disease at all in mallard ducks who may shed it in feces or respiratory secretions for two weeks after infection. And we have no data on the viruses’ behavior in the dozens of other species of waterbirds who may acquire the virus.

Waterfowl aggregration as petri dish? (photo: USFWS)

Waterfowl aggregration as petri dish? (photo: USFWS)

What to do? USDA and other agencies will continue to monitor both poultry and wild birds closely for new viruses, new reassortments, and new geographic occurrences of these HPAIs. So far, we are not seeing it here on the East Coast, but we should behave as if we may. Since you Seanetters handle dead birds as a matter of course, it’s a good time to review saftety practices that are good habits to maintain whether or not a flu outbreak is underway. The CDC’s full suite of recommendations for working with infected birds or carcasses of bird flu victims include goggles, gloves, coveralls, masks and the like. For our purposes, given that the CDC lists the risk of human infection from these H5s as very low, we will continue to recommend wearing gloves whenever handling a carcass for tagging or measurements, discarding the gloves after use, and washing hands thoroughly after the walk. As always, if you have a weakened immune system for any reason, you may be at increased risk of any infection, not just avian flu, and may wish not to handle dead birds at all. If this is the case, get in touch and we can figure out some accommodations. Should you find yourself ill, particularly with a respiratory illness, the CDC asks that you disclose any contact with potentially diseased birds to your doctor. Doctors (and vets, for that matter) are taught, “when hearing hoofbeats, think horses, not zebras.” Because of this, your doctor is unlikely to think of avian flu as a potential diagnose unless you disclose your exposure. Contrary to what we all may think, it’s not usual to muck around on the beach with dead birds. On the other hand, anyone who has walked on a soccer field or golf course has been exposed to more potentially infectious goose feces than the average Seanetter meets in a year of tagging carcasses, so do maintain a sense of perspective.

I hope this has served as a helpful outline of the problem, and not has not unduly alarmed you. Your risk of becoming sick from handling dead birds is extremely low, but particularly if any of you should happen upon a major mortality event involving waterfowl (the main species groups affected by these viruses) I wanted you to be informed participants.





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.





A good day to contemplate mass mortality

27 01 2015

IMG_6387Snow is general across New England today. I can’t actually open my front door due to four foot snow drifts, but the view of the mounting piles and sideways blowing snow hints at the conditions. A couple of our Seanetters have written, pondering what they might find on their beaches once this blizzard winds down. Dennis Minsky closed his email to me with the words, “God help wildlife tonight.” Indeed, post storm, we do often see upticks in seabird mortalities. Species groups like alcids, already on a knife’s edge of survival during the harsher months, can be pushed over the edge by a bad storm and turn up in wrecks along the shores or even well inland. Storms can be one of the many stressors that may converge on wildlife and lead to mass death. A new paper out in the Proceedings of the National Academy of Sciences looked at patterns of these mass mortality events (MMEs) over decades and across multiple classes of organisms. Their findings do much to elucidate some causes of these events, but also to point out the challenges in tracking, reporting, and measuring them in wild populations across the globe. Some die-offs may simply be more conspicuous due to geography and timing, and others may remain unreported and undocumented simply because of the obscurity of where or when they occur. Some of it comes down to a variant of the tree-in-the-forest question: “if thousands of alcids die in the Atlantic, and no one is there to count them, does it make a sound?” The authors of the paper had to grapple with determining how many MMEs happen, and how may get reported in the scientific literature.  Overall, these researchers have striven to account for these kinds of observation bias, and though it cannot be entirely eliminated, their general findings are quite interesting.

MMEs were rarely reported at all prior to the 1940s, so the authors of the study analyzed only the reports since then. As you can see in the figure below, the number of MMEs documented (and we know not all are documented) has increased in general–the colored bars show the number of events reported for each five year interval. The apparent declines in numbers of MMEs in most of these groups over the past decade is due at least in part to the delay between when an event occurs and when a scientific paper is finally published on that event, which can take years or even decades. The dashed lines show the upward trend in scientific papers published on MMEs, and it reliably increases across all groups.

Screen Shot 2015-01-27 at 11.59.51 AM

What these particular graphs do not show is the magnitude of each MME. Some die-offs are truly massive, and others are on a smaller scale. Further complicating the issue is the overall population size of the species. In a very common species, millions of individuals could die, drawing a great deal of human attention to the spectacle, and yet have little impact on the population’s overall viability. A very rare species might lose only a hundred of its number and face local or regional extinction without attracting much, if any, human attention. The differences in MME magnitude varies across different taxonomic groups too. In other words, the trends in magnitude of die-offs in amphibians do not hold for birds or mammals. The reasons for this are not simple or straightforward. There are several factors that may be at play, and sorting them out is challenging. The scientific community does shift in its foci over time, and while disease or toxic algal blooms may be in the spotlight for several years, interest in those can wane as scientists shift toward a focus on prey availabilty, or climate change as drivers. This is not either/ or of course, but these kinds of shifts do play a role. If we have not had entirely consistent attention on all the different potential causes of MMEs across all taxa, then we may have missed some significant ones while attention was turned elsewhere. In addition, there are the issues of scientific advances, which have made it possible to pinpoint causes of MMEs like algal toxins or viral diseases that simply could not be diagnosed fifty years ago due to lack of technological ability. These researchers also point out that, while scientists travel the globe in the course of their work, coverage is not uniform. Many more investigators are at work in Europe and North America, for instance, than in most regions of the developing world. These biases can lead us to miss entirely die-offs that happen in these less scrutinized regions.

What does appear clear is that, rather than pinpointing a single cause of wildlife die-offs as the main culprit, the number of events due to multiple stressors is likely to increase. Climate change can induce thermal stress on organisms not adapted to warming oceans, prey availability can threaten the survival of creatures already marginal in their foraging, and increasing severity of storms, droughts, and floods will converge on these species more and more often. Human-introduced pathogens will continue to pile on as well. What this paper tells us is that, in addition to doing whatever we can to address these threats, we must also make sure scientists are continuing to focus on mass mortality events. Interestingly, it is still the case that most wildlife mortality events are reported only in newspapers, and never make it into the primary scientific literature at all.

All the more impetus for me to finish up verifying all your volunteer data and get some publications out on seabird mortality on the east coast. I suppose a blizzard day is a good time to hunker down and do some of that work.





Vaccinating wild birds?

5 01 2015

For most of its history, the field of wildlife management largely ignored or dismissed the role of disease in wildlife populations. Not to say they denied the existence of disease, certainly they did not, but for many years, its role was seen as one of natural correction: when populations grew too large or dense, a disease outbreak would prune down those numbers, bringing the population back to a sustainable level. Indeed, for millennia, this was the case. Now, the study of wildlife disease and disease ecology is booming. What happened? We did.

When wild populations evolve alongside their diseases, be they viral, bacterial, parasitic, or otherwise, the two are engaged in a constant arms race. Pathogens evolve new ways to infect and spread, and hosts evolve new defenses. This dynamic breaks down, however, when a pathogen infects a host population with no previous exposure or defenses. In human history, there were the infamous smallpox outbreaks among Native Americans upon first contact with Europeans. The Pilgrims arrived in a land largely emptied of its native human inhabitants after they were nearly annihilated by infections brought by previous European traders and their rats. Without natural immunity, what we call a naive population can be very nearly exterminated by a disease that coexists in ancient balance in another population.

Things are not much different in wildlife. Wild populations exposed to new diseases carried across oceans by human travelers can face extinction when those diseases run unchecked through their ranks. We have seen this happen with the spread of avian malaria in Hawaiian songbirds, and with the Geomyces destructans fungus that causes White Nose Syndrome in North American bats but seems to cause no harm to its normal European host species.

As awareness has spread of the threat posed by disease in wildlife, people often ask why we can’t develop vaccines to combat them. The typical response is that it would not be practical. For many reasons, this is true. First, developing a vaccine is expensive and without a large scale market for the product, it’s not likely to get done. Wildlife medicine doesn’t pay well, I can tell you from personal experience, so the economics alone are daunting. Second, not every disease is well suited to vaccination. We mainly vaccinate against viruses, though some vaccines (Tetanus, Diphtheria, e.g.) target the toxins released by bacteria. Even within viruses, some are stable and relatively unchanging, while others are constantly mutating. This is why we have a standard vaccine for rabies (stable), an annually shifting one for flu (not so stable or consistent), and no vaccine for HIV (constantly mutating). But let us assume we had a vaccine on hand that could combat a particular disease threatening a population, and that we knew we could capture enough individual animals to administer it to a high percentage of the population. Even then, there are challenges.

When I was a first year vet student, I had to get a series of rabies vaccinations. We all did, given our line of work and our higher than average risk of exposure. After that initial three shot series, we were told we should have a titer checked every two years to make sure we are still protected. A titer tests the blood to see what level of antibodies are still patrolling for a particular virus. So far, every two or three years, my titer has shown that my body is still alert to the threat of rabies, and if the virus did find its way into my body, the level of antibodies in my system would be sufficient to neutralize those viral particles and destroy them.

Cory's Shearwaters in their nest burrow. (Photo: JardimBotanico)

Cory’s Shearwaters in their nest burrow. (Photo: JardimBotanico)

The reason I have to be checked so often is that this response is variable. Some people never need a booster shot after receiving the series. Others do. The level of antibodies can decline over time. Knowing how long a protective level persists is critical to any vaccination plan, so when contemplating vaccinating a wild population, we must have a sense of how long the protection will last. If an animal would require annual boosters, that vaccine is not likely to be of much use long term in wildlife where capturing individuals repeatedly ranges from difficult to impossible.

The question of vaccinating wild animals must also encompass the life history strategy of the particular species. Many seabirds, for instance, are extremely long-lived, and their population structure is based on an extended juvenile or subadult phase, low annual reproduction, but a tradeoff in many, many years of reproduction (for a particularly amazing example, read about Wisdom). In such birds, if a vaccine were found to lead to multi-year protection from a serious disease, the balance could tip toward attempting it.

Thinking along just these lines, a team of researchers set out to study vaccine responses in Cory’s Shearwaters, another long-lived seabird species. Some seabirds are susceptible to Newcastle Disease Virus, a potentially deadly disease that also affects domestic chickens. Given that last point, there is a vaccine currently available for use in poultry, and these researchers administered it to shearwaters instead and then tracked not only their own bodies’ responses over a period of years, but also how the antibodies passed into the birds’ eggs and persisted in hatchlings. What they found was that the adult birds did mount an immune response to the injection and that the antibody levels in their blood rose quickly, and then gradually declined over a period of years. Some of the birds received a booster shot a couple years after the initial one, and the antibody levels rose again in response to that. Levels of antibodies passed to the chicks as the egg was forming persisted after hatching, and the higher the levels of antibodies in the mother at the time of reproduction, the higher the levels in the chicks.

Antibody levels in adults (upper graph) and chicks (lower). Green bands are from unvaccinated birds. Orange band on upper graph are adults vaccinated once. Blue band are birds that received a booster shot two years into the study.

Antibody levels in adults (upper graph) and chicks (lower). Green bands are from unvaccinated birds. Orange band on upper graph are adults vaccinated once. Blue band are birds that received a booster shot two years into the study.

Just as every virus is different, every vaccine is different, and the results from this study do not mean that all vaccines would result in persistent antibody levels for several years. Additionally, what made this multi-year study possible is the site fidelity of shearwaters and other seabirds, many of which return year after year to the same exact burrow or nest site, and can be captured and resampled reliably. For many wild animals, this type of resampling is simply impossible, as would be booster shots. Finally, this was a study aimed at determining persistence of antibody levels, not at actually protecting the population from Newcastle Disease. Generally, something around 80% or so of the population need to be vaccinated to keep a disease from spreading. To attain those kinds of levels would be incredibly labor intensive, and in many cases, not feasible. But this study is an indication of the rising profile of disease ecology in wildlife management, and an awareness that we must shift finally away from a view of disease as a natural corrector and toward viewing it as another of the anthropogenic threats we created, and that we must strive to address.





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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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.