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.
image





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.





Dead Bird Quiz: multi-level play edition

23 09 2014

At various levels of difficulty, here are your three Dead Birds for the week:

Bird A was found by Marcia Lyons in North Carolina in June. Culmen is reported at 63mm. Other measurements not obtainable due to carcass condition.

Bird A, first view (Photo: M. Lyons)

Bird A, first view (Photo: M. Lyons)

Bird A, second view (Photo: M. Lyons)

Bird A, second view (Photo: M. Lyons)

Bird B is also a Marcia Lyons find, this one from just yesterday. Reported measurements are: Culmen: 61mm; Tarsus: 71mm; Wing chord: 45cm.

Bird B's underside (photo: M. Lyons)

Bird B’s underside (photo: M. Lyons)

Bird B's upper side. (photo: M. Lyons)

Bird B’s upper side. (photo: M. Lyons)

Bird C is mere shadow of its former self. More specifically, just a wing of its former self. The specimen was found by Kathleen Kelly in Maine back in April. Wing chord reported at 31cm.

Bird C: underside of wing (photo: K. Kelly)

Bird C: underside of wing (photo: K. Kelly)

Bird C upper wing. (Photo: K. Kelly)

Bird C upper wing. (Photo: K. Kelly)





Is wind power bad for birds?

20 09 2014

As promised, I spent some time reviewing the scientific literature on wind farms and their impacts on bird populations. While the details are complex (and I will get to some of them), the short answer to the question, “Does wind power kill birds?” is, “Yes.” The longer answer is, “Yes, and so do all other forms of power generation currently in use. Generating power kills birds.” The still longer, and better, answer is as follows:

First off, the topic of birds and wind power is far too broad for my poor capacity here on this blog. The issues involved in land based wind farms are different from ocean based ones, and wind turbines affect different species of birds differently. This is not to mention the additional suite of circumstances around wind turbines and their effects on bats. I can’t cover it all. So, since this is the SEANET blog, I elected to restrict myself mainly to an investigation of the impact of ocean-based wind power on seabirds. That’s in itself a broad topic, but here goes.

A wind farm off the shore of Denmark. (Photo by Koppelius).

A wind farm off the shore of Denmark. (Photo by Koppelius).

Wind farms can kill or harm birds in more ways than one might expect. There is the obvious and violent spectacle of birds killed due to direct flight into the turbine blades or the support structure. But there are subtler impacts as well. While the wind farm is being constructed, birds will be displaced substantially from that location by all the activity. Once construction is complete, the human presence is much reduced, but the turbines themselves alter the seascape from ocean floor to the tip of the tallest blade. The footings and pylons holding up the turbine disrupt and reduce the area of ocean floor and water column available for foraging, and birds may well steer clear of an extended area around the farms. If that area was a rich hunting ground, then the birds will suffer for its loss. How much? Depends on the wind farm, depends on the bird, depends on the prey. Up above the water’s surface, in addition to birds that are killed outright by the turbine blades, there are the birds that instead fly around them and pass by safely. But how far around do they fly? If, for instance, on a migration, a flock of birds gives a wind farm a very wide berth, they will have to increase their energy use for the extra flight time. That demands extra foraging to make up the lost calories. For some species where survival is on the slimmest of margins energetically, might this tip the balance?

While there are currently no offshore wind farms in the United States, Europe, led by Germany and its much touted Energiewende, have been investing heavily in such farms, and this gives us an ever increasing body of scientific literature on the observed impacts at real-life sites. Here in the U.S. many scientists have been using mathematical models to game out what impacts wind farms of various sizes, heights, and locations might have. Taken together, we gain ever more insight into how to sensibly and responsibly navigate the way toward cleaner energy sources.

Pulling out just a few papers, it becomes clear how unclear the answers become when we try to group even all seabirds together and assess risk. Collisions with turbines are fairly rare in seabirds overall, and especially in comparison to some nocturnally migrating songbirds, for instance. Many water birds actively avoid the turbines, flying above or below the blades, or around the entire farm. A 2012 study using radar detection of migrating pink-footed geese found that 94.25% of all flocks identified flew safely around the farm. Other species, however, are less successful in avoidance; a 2013 study in Scotland identified gulls, gannets and skuas as being at higher risk for collisions, and white-tailed eagles appeared to show little to no avoidance behavior.

As to the issue of loss of foraging grounds, the impacts will vary from species to species. By way of example, however, I can offer up the Black Scoter, and a study out in January from researchers in Rhode Island. This paper points out that while many species of seabirds will avoid a newly built wind farm, they will often begin to return to forage in the area after three years or so. It seems that many birds are able to acclimate to the presence of the turbines. A similar phenomenon has been observed at land based farms, where mortality from collisions declines over time as the birds learn that the turbines are there and adjust their flight patterns accordingly. In a species group that tends to be very long-lived, like seabirds, we could certainly anticipate that the knowledge a bird gains about where the farms are and how to work around them, once acquired, would continue to serve that bird over its potential decades of life.

An aggregation of scoters. (Photo: Kevin T. Karlson).

An aggregation of scoters. (Photo: Kevin T. Karlson).

But let’s assume that the birds leave the area of a new wind farm and never return. What does that mean for the species? Again, it depends on the species. Black scoters are only loosely tied to particular foraging waters. Even in the absence of any offshore development, individual birds may spend the winter off Rhode Island one year, but the next year be somewhere closer to Delaware, or Cape Cod. In a species with this kind of flexibility, the impact of losing the foraging territory may be minimal since the birds are quite accustomed to moving around and trying new spots. But in a species with greater site fidelity, a poorly placed wind farm could have profound effects. That, in turn, leads us to the question of how we define well versus poorly placed wind farms. Rhode Island, Massachusetts and North Carolina are all examples of governments who have chosen to take on the process of marine spatial planning. They have realized that random and haphazard development of the marine environment could mean catastrophe for wildlife. By taking a rational, evidence-based approach, these plans lay out the best and worst places to site a wind farm or other offshore development project. Black scoters forage for invertebrates like mussels relatively nearshore, over hard bottom or coarse sand, and in relatively shallow waters. A wind farm placed in an area that matches those characteristics would be highly likely to impact Black scoters. The same farm shifted out of Black scoter prime range? Rather unlikely to have a major impact. Take a look at this figure from a 2013 paper by Winiarski, et al:

Figure from the Loring, et al paper on marine spatial planning.

Figure from the Winiarski, et al paper on marine spatial planning.

On the left side are maps of the Block Island area showing the relative importance of the habitat to scoters. The darker the area, the more critical the habitat to bird survival. Darker areas are classed therefore as “priority habitat.” On the right side are graphs showing various species or species groups and how they are projected to decline based on how much of their habitat has been made inaccessible to them. Eventually, if you left zero habitat at all, there would be no birds left because they have no place to be. But up to that point, removing habitat will affect different species differently. The longer the colored line remains level, the more resilient that species is to loss of habitat, possibly because that species is flexible in its habitat use and can shift somewhere else. Other species with a more even distribution decline steadily as soon as habitat begins to become unavailable.

Moving down the figure, and looking at b) and c), we can see areas on the map that have been whited out completely. This is a simulated wind farm, and the model treats it as a total loss in terms of habitat. If a wind farm were sited there, we can look at the line graph and see some subtle shifts. Most notable in b): the reddish line representing Common Loons drops off quickly before leveling off somewhat. This indicates that the habitat chunk removed just west of Block Island is a particularly important one for loons. The change is c) is even more striking. There, the removal of a different piece of habitat to the southwest of Block Island causes a precipitous drop in the distribution of scoters, indicating that that area is of significant importance to their population. By manipulating these models, the scientists can come up with sites that we can expect will do the least harm. When habitat farther offshore, with fewer of the characteristics sought by seabirds, is removed in a simulated development project, the impacts on the birds are reduced. Such areas, shown in light gray in d) and e), would be better places for a wind farm, for the birds at least. For Rhode Island, the planning map thus recommends that wind farms not be sited within five kilometers of shore, or in waters less than 20 meters deep.

The key point of marine spatial planning is the planning. The creators of these maps and documents and guidelines realize that we need cleaner energy, and ocean-based wind is a huge potential source. By choosing the right location, we can also mitigate the risks to wild birds. Just like a LEED-certified, net zero office building is far superior to a conventional building in terms of sustainability, it would be irresponsible folly to construct it in the middle of a wetland housing the last population of a critically endangered species. We need clean energy, and we need to find the right places to get it.

To the question of whether or not we should be building wind farms at all, knowing they kill individual birds and pose some level of threat to the population, we must look at the alternatives. The fact is, we need power. The question is, where are we going to get it in the future. A 2009 analysis by Benjamin Sovacool sought to quantify how many birds are killed per kilowatt-hour of energy produced by various types of power, from fossil fuels, to nuclear, to wind. Some critics of wind power have pointed out that the reason so few birds are killed by wind turbines each year in the United States is solely because we have so few wind turbines. Scale up the technology, they argue, and the numbers of birds killed will skyrocket. Sovacool attempted to neutralize this factor by calculating not total mortality, but mortality per kWh, extrapolating out to an energy future where wind power is supplying far more of the grid.

Figure from Sovakool (2009). Blue shows annual avian mortality from each power source, and red shows mortality per gigawatt-hour of electricity generated.

Figure from Sovakool (2009). Blue shows annual avian mortality from each power source, and red shows mortality per gigawatt-hour of electricity generated.

Though his exact numbers have been challenged, and I agree with some of the critiques of his techniques and summation, his fundamental idea is sound. When we look at the entire fuel cycle of, say, coal versus wind power, we will come down on the side of wind being substantially more bird friendly. Sovacool points out that mining coal or drilling for oil destroys habitat for birds. Of course, building wind turbines does also. The most egregious methods of extraction, like mountaintop removal for coal, are the opposite of the kind of reasoned, strategic approach seen in a marine spatial plan. But turbines do disrupt habitat as well. Then comes the generation of power. Fossil fuel plants themselves kill large numbers of birds through collisions with their cooling towers and other structures, just as birds collide with cell phone towers and skyscrapers. Build something up into the air, and birds will hit it. An estimated 175 million birds are killed annually in collisions with transmission lines feeding the plants themselves. This issue of power lines remains for wind power too, of course; we have to move the power around and distribute it after all.  So by some measures, it seems that the different power sources have similar liabilities in terms of avian mortality. Add in, however, the mercury and the acid-rain producing compounds that enter the atmosphere through the burning of fossil fuels, and the balance shifts to favor wind power. But even if we judged them equal up to that point, we’ve left out the greatest existential threat of them all: climate change. Whereas some species are more affected by wind turbines than others, it’s almost impossible to find a bird species that will be unaffected by climate change, and for some, it will spell extinction.

Sovacool also points to all the other anthropogenic causes of bird mortality: an estimated 100 million to domestic cats, 100-900 million dead by collisions with windows. “However,” he writes, “since house cats and office windows do not yet produce electricity, the comparisons are less relevant than those that assess avian deaths from other sources of electricity generation.” Less relevant to questions of our power supply, true, but the comparison is still useful. House cats are not inherently evil (though I know people who will argue that point), nor are office windows. House cats safely indoors are lovely pets to have. House cats hunting outside are a menace. Office windows are nice to gaze out of. Office windows illuminated at night when throngs of nocturnally migrating songbirds are passing through that exact geographic corridor are a killing field. Yet we see scant efforts at legislation to block new construction of office buildings, or even legislation to make windows in new construction less hazardous to birds. I don’t see legislation aimed at keeping house cats indoors either, and it’s not as if having a cat outside does us some essential service, as if it were a public utility. The fact is that knee jerk opposition to wind power on the basis that some birds will be killed by wind farms is not credible scientifically. Birds die by our actions in droves. We are always making the cost-benefit analysis of using cars, living in buildings, having cell phones and many other things that kill a lot of birds. We have the science on how to intelligently site these projects. We can put them where they will do the least harm to birds, knowing that the shift from fossil fuels to wind is, in itself, a benefit to birds. Not to an individual bird killed by a turbine, I’ll grant you that. But we are in the business of the population level threats. And those don’t get any bigger than our continued reluctance to shift to renewable energy.

 








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