Posts Tagged ‘science in action’
April 29th, 2012 | Meera
Alaska, wrote John Muir, is full of food for man and beast, body and soul, though few are seeking it as yet. Were one-tenth part of the attractions this country has to offer made known to the world, thousands would come every year, and not a few of them would stay and make homes.
He wrote: How truly wild it is, and how joyously one’s heart responds to the welcome it gives.
Friends, I found myself hungry in body and soul last year, so I went north. And this year I am still hungry, so I am going north again.
Between tomorrow and mid-July, I’ll be working in the wilderness of far western Alaska, serving as a field volunteer on a Fish and Wildlife Service project. There will be four of us, two scientists and two volunteers, camping out on the vast montane tundra, studying the breeding habits of the rare, secretive, and by all accounts beguiling shorebird known—charmingly—as the Bristle-thighed Curlew (Numenius tahitiensis).
I wish I could post updates from the field like I did last summer, but unfortunately we’ll be entirely offline and out of cellphone access, so I’ll do my best to take notes and tell you a little bit when I get back about whether John Muir was right. (Spoiler: I’m pretty sure he was.)
In the meantime, all my love, all my thanks for being so supportive of these excursions, and if we haven’t already talked about all this hunger business, my book Mountainfit will tell you everything you need to know. If you are new to The Science Essayist and aren’t quite sure whether you like my writing enough to spend five dollars on it, this review from doctoral candidate Sienna Latham—who studies the history of science and is one of the wonderful people who backed my Kickstarter project to get the book written—might give you a sense of what it’s like.
Be safe, friends. I’ll talk to you soon.
October 31st, 2011 | Meera
Happy Halloween! Today seemed like an excellent day to make this post.
Entering the bird lab this past Thursday morning, I found Mary, who usually works at the sink, sitting on a stool beside the large metal prep table that dominates the room. In front of her were two plastic trays; on each, several tidy rows of specimens were arranged. The birds that made up this small collection represented three different species: Dark-eyed Juncos (Junco hyemalis), Nashville Warblers (Vermivora ruficapilla), and White-throated Sparrows (Zonotrichia albicollis).
All three are extremely common birds in the Chicago area at this time of year, either because they’re migrating through on their way to warmer southern climes, or because they spend the winter here.
And all three are known to me personally from morning walks through the Wooded Island in Jackson Park, the treed and windy urban oasis by the lakefront where I saw the distempered raccoon earlier this spring. I love the sight of dozens of dark gray Juncos against patches of snow on the ground, like a fireplace’s worth of cinders someone has rolled up into cozy little balls. Nashville warblers make jaunty little tail flicks as they forage through low trees and shrubs (often that’s all I see of them, an olive whisk-whisk-whisk before they rustle away through the leaves). And the mustard-yellow smudges next to each eye on White-throated Sparrows always make me imagine these fluffy, familiar creatures having just feasted messily on a stash of abandoned hot dogs.
The fact that Mary was working on these birds wouldn’t, in and of itself, have been of much note except that the specimens were in a form that I’d never seen before in the lab. Normally, these are species that Dave chooses to preserve as skeletons. One of the advantages of doing so is that there are many measurements it’s possible to take from a skeleton that it’s impossible to take from a study skin. To prepare a specimen for being skeletonized by the dermestid beetles, volunteers must first remove all its feathers and skin, a process called “roughing out.”
But the specimens Mary was working with seemed to have gone only part-way through this process. On the Nashville Warblers and the White-throated Sparrows, the feathers from their bodies had been removed, but those on their heads had been left in place. And on the Juncos, tail feathers remained as well.
In this state the specimens appeared, I confess, both fascinating and a little macabre. The juxtaposition of intact, feathered crowns, their plumage still beautifully soft and many-colored, with the dark red muscle of de-feathered bodies, created an incongruity—the likeness of life next to the unmistakable sign of death—that forced me to stop.
Why had some feathers been left on these birds?
Mary soon explained that in each of these species, subtle but significant differences in plumage coloration can be observed. Such variations raise a host of scientific questions (Are the disparities related to sex, age, or region? Can they be traced to genetic differences? Is one form of coloration more common than another, and if so, why? Does the prevalence of each pattern change over time?).
To document these variations, Mary was collecting caps from all three species, as well as tail feathers from the Juncos—because these were the parts of the birds’ bodies where the differences occurred. This way, the caps and tail feathers could become part of the museum’s collections and potentially help to answer some of these questions.
But when she was finished collecting what she needed, the beetles would go on to skeletonize the rest of the specimens’ bodies as usual, thus preserving the ability to take bone measurements from them in the future. The fact that I’d seen the birds’ bodies in this state was a coincidence: an accidental glimpse at a bit of scientific frugality.
Here are some of the variations this kind of data will hopefully help to quantify:
Juncos can have crowns that vary from a light gray to a deep black, sometimes tinged with brown—and while all Juncos have white outer tail feathers and black inner tail feathers, there can be considerable variance in the amount of white and black on the intermediary feathers. This photo doesn’t show the subtle differences in the shades of the crowns very well, but you can clearly see how much more black than white there is in the tail feathers of the bird in the foreground, and how much further out the black extends to the edges of its tail.
Nashville Warblers can have a patch of wonderfully rich chestnut-colored feathers in the center of their crowns, something I’ve never noticed when birding because the tiny flecks of red are all but impossible to see amidst or underneath their otherwise gray head feathers. Adult males all have some red in their caps, but the amount can vary widely; and some adult females have a little ruddiness there, too, while others have none. These differences are unfortunately very hard to see in the photo I took, but if you squint you might be able to see some red stippling in the third specimen from the left.
Finally, White-throated Sparrows actually have two well-documented morphs, or variant forms. You can see these quite clearly in the photo above: one morph has distinct black and white stripes running vertically down its crown, while the other has black and tan stripes arranged in the same pattern. Both morphs can be found in both sexes.
DNA analysis has shown that this polymorphism in White-throated Sparrows arises from genetic differences. Both White Stripe and Tan Stripe birds, as they are usually called, show a slight preference for mating with individuals from the other morph. This opposites-attract tendency (which goes by the unwieldy name of “disassortative mating”) keeps the approximate proportion of each morph in the overall population stable, so that neither morph disappears or becomes dominant.
Most fascinating of all, at least in the case of White-throated Sparrows, the morphological variations we see in their crowns are also associated with clear behavioral differences. White Stripe males are more aggressive and more showy—they’re more likely to engage in “spiraling,” a wonderful-sounding behavior that involves singing as they ascend the branches of a tree by circling it. They’re also less dedicated providers of parental care, and less monogamous than Tan Stripe males. As for White Stripe females, they are almost as bold and selfish as their male counterparts. (This may explain why both WS males and females seek out calmer, more reliable partners from the opposite morph.) For more on this subject, I’ll point you to this excellent post by GrrlScientist, who explains the genetics behind these behavioral variations far better than I could.
What I love about my own experience of all this is that it illustrates so clearly a principle I’ve always felt to be true about the study of natural history. That is, the macabre (like beauty) is not a thing that exists as an inherent property of the world, not something with a palpable presence in time and space. Instead it arises out of the complex interaction between ourselves and the world. Even if disquiet is our first reaction to a memento mori, it need not be our last.
But to the extent that encounters with the macabre invite curiosity—like the curiosity that struck me so forcibly when I walked into the lab and saw those unusual-looking specimens on Mary’s trays, and led me to learn some of the things I’ve shared with you today—I think it’s an extraordinarily useful quality in science.
I would be remiss if I didn’t tell you about two additional things I hope you will investigate:
1) Flinchy, the t-shirt company co-founded by my favorite fellow bird lab volunteer, Diana Sudyka, has several new designs available for purchase. I own one of them, and can testify to its quality and attractiveness. And greater luminaries than me endorse Flinchy shirts, too.
2) I wrote a piece for the Scientific American Guest Blog this week about my rather extraordinary friend Nina and her Field Museum project, LinEpig. You can find it here, under the curiosity-provoking (though not macabre) title “Internet Porn Fills Gap in Spider Taxonomy.” Nina picked the title, because she knows even better than I do that first you catch the eye, and then you tell the story.
Till next time, dear readers-mine. I hope it won’t be so long again.
July 22nd, 2011 | Meera
The Science Essayist is volunteering at a bird observatory in Sweden this summer.
Leaning over the work table in one of the observatory’s ringing huts last week, I raised a hand to smooth the lists of birds we keep pinned to the wall. They show each of the dozens of species we might encounter here: its common names in English and Swedish, its scientific name, the five-letter abbreviation by which it is identified in our protocols, and the standard ring size it takes.
(An aside: Some of the abbreviations assigned to bird species are tiny bits of sound-poetry, delicious to say. I like it when we catch a Redpoll, and not just because they are beautiful birds. Their code, derived from the scientific name Carduelis flammea—Redpolls are also known as Acanthis flammea by some taxonomists—is like the politest little cough. CAFLA!, I announce happily as I write it down. CAFLA! Forgive me; I have something in my throat—CAFLA, CAFLA, CAFLA.)
I don’t know if my fellow volunteer Peder saw my wedding band glinting as I stood with my hand on the wall. But perhaps that’s why he said at that moment—his voice rich with the delight of a clever observation—”But Meera’s been ringed. What size is your ring, Meera?”
I smiled, both because I like Peder’s sense of humor and because there was pleasure in taking his question, which required no serious answer, seriously.
What size was my ring? Did it conform to the requirements of comfort and utility assigned to every ring we put on a bird in this hut? Was it loose enough to slide easily up and down my finger, but snug enough not to fall off? When it was placed, did someone take care not to harm me? Was it unobtrusive, in no way impeding my flight, feeding, or other natural behaviors? Did its presence on my finger serve a meaningful purpose in the world? And could you trace my history by it?
I don’t remember what I said to Peder then, twisting my ring affectionately and thinking on these questions with ducked head and wondering mind. Today—watching my brown hands fly over the keyboard, marked by a flicker of white gold—I am still sitting with them.
But when it comes to the birds, at least, I have some answers I can give.
Many of you reading have first-hand experience with the processes and purposes of ringing (or banding, as it is called in the U.S.). You, friends, don’t have to stay for the rest of this post—although I would love it if you added a comment or let me know how you do things. For the rest of you—and for me, since I am learning these things along with you—I have written a small primer. Ready? Grab a fika. This will be long, and though I find it fascinating, it won’t be very poetic. Something sweet will help us all stay focused. :)
A Bird in the Hand
To work with a wild bird, of course, you must first have access to it. If you are ringing birds in nest boxes, as I was helping Stefan do earlier this summer, this is fairly straightforward. You simply check each nest box periodically, noting which are occupied, which have eggs, and later, which have nestlings in them.
If you know approximately how old the chicks were when you last checked on them and how old they will be when they fledge, you can pick a day to ring them—sometime when they’re well grown, but not quite ready to leave the nest. At that point, you can safely pluck the clutch of nestlings out one by one, ring them, and put them back inside. Depending on the species, you’re more or less likely to be able to ring the mother as well—flycatcher parents tend to flee the nest when you approach; tits sometimes stay inside.
Besides nest box ringing, the observatory also conducts mist-net ringing each summer. (This is what I’ve been helping with for the past few weeks, since the Great Snipe tracking began winding down.)
Mist nets are very fine nets constructed of strong black nylon, with mesh sizes that vary from about 16mm to about 120mm; you need a larger mesh to catch big birds like waders and raptors, and a smaller one to catch little birds like warblers and finches. The nets get their name, as you might imagine, because when unfurled they become virtually invisible to birds (and preoccupied humans, as I have proven on more than one occasion).
Each net comprises five vertical sections of netting separated by five horizontal threads; you set it up so that the horizontal threads run taut between two poles and the vertical sections hang loosely below them, forming several pockets into which birds can fly. Nets are usually set up in the early morning and taken down or rolled up in the early afternoon. In between, birds are active but the sun isn’t shining down too hard. If it becomes very hot, windy, cold, or rainy when you are using mist nets, they are promptly closed so that you don’t trap birds under adverse conditions.
Amazingly, I have no unfurled mist nets among the nearly 500 photos I’ve posted of Sweden so far. Here is one from my wonderful Flickr contact Andy Jones, of the Cleveland Museum of Natural History. Ours look exactly the same, but surrounded by tall grasses and wildflowers.
Once you’ve opened a net, it is checked frequently so no bird remains caught for very long. The great majority of the time, birds become only lightly tangled, and removing them takes moments. Occasionally a bird will be more difficult to extract (in tricky cases, beginners like me should always call for help from more experienced ringers, so that the bird can be freed as efficiently as possible). Either way, you follow the same basic steps. First, determine which side of the net the bird entered on, and work on that side; next, free the feet, then the wings, then the head, since that’s the opposite order from which most bird parts encounter the net.
The removal process, though usually straightforward, is the most delicate part of the ringing operation. It requires patience, care, and a constant attention to the welfare of the bird you’re working with. You may be being swarmed by mosquitoes or gnats or tiny evil flies, for instance, but if you have a bird in hand, you can’t twitch an arm suddenly to shoo them away. (Me, if this gets very bad, I swear under my breath. I don’t think anyone but the birds has heard me yet.)
Once you’ve freed a bird, it is placed inside a cotton drawstring bag and taken somewhere else to be processed: in our case, a ringing hut.
A Minute of Science
While there are many steps in processing a bird, experienced hands can perform them incredibly quickly—usually in under one minute. It will take me longer to write about this and you to read it than it takes most birds to make their way out of the ringing hut, and I’m not even going to describe the steps in detail, just list them.
The first thing a ringer does after removing a bird from its bag is identify it. This dictates the ring size it will take, because that is dependent on the average diameter of each species’ leg. The smallest ring we have is a 0.5, which we put on tiny things like chiffchaffs; the largest, spares of which we own but almost never use because our operations aren’t designed to trap anything except songbirds, is a 93—for something magnificent like a crane.
Next, the bird is ringed using a special set of pliers with round openings. These help you to properly bring the edges of the ring together without any danger of squeezing the bird’s leg. I have seen experienced ringers do this so smoothly that I am barely ready to write down the ring number before they are done.
Finally, several pieces of information are taken that will be associated with the bird’s ring number.(Every country in which birds are ringed has a central database to which these records are uploaded.) Here, we sex and age the bird to the degree that this is possible using physical signs, and then take a fat score, a wing measurement, and weight. We also look for the presence of a brood patch (a wrinkly, swollen area on female birds’ bellies that indicates they are in nesting mode), and determine what stage of feather growth young birds are in and what stage of moult, if any, adult birds are in. None of this data is necessarily all that significant in isolation, but collecting it for millions of birds worldwide each year adds a tremendous amount to the knowledge we have about various species.
If an already-ringed bird is captured, all the same information is collected and its ring number taken down. When that record is uploaded, whoever ringed the bird originally is automatically notified, so they know where that individual has been. I imagine it must be rather thrilling to receive one of these notices. Perhaps it’s a little as if a message you’d put in a bottle had been found across the seas.
After all this, the bird—which, if it is typical, has stayed calm throughout—is released through a small hatch in the side of the hut. Or, if it is a fledgling, it is taken back to the area where it was caught, with its siblings if any were trapped at the same time. We do this so that young birds can easily find their way home. I have returned fledglings several times and I can’t tell you how reassuring it is to hear chicks and parents calling to each other as you approach their nest.
As I said, most often a bird is held in the hand for less than one minute. (It took me about 15 to write this, but things might have gone a little quicker if I hadn’t run out of coffee one section ago. How are you doing, by the way? Any fika left? I’ll try to be quick now, although this last bit is arguably the part I most want you to understand.)
Varför Vi Gör Det (Why We Do It)
It’s all very well to tell you what we do when we ring birds; what perhaps seems even more mysterious, at least if you haven’t thought about it before, are the reasons we do it at all. A dear friend—and I hope she doesn’t mind me quoting her, because I think her words reflect what’s in many people’s minds—commented last week on a photo I posted of a female chaffinch being processed: “I get science and all that, but from a bird perspective, where you are must be a torture chamber.”
Let’s talk about that second part first. It’s perfectly true that being caught in a mist net and ringed is no bird’s idea of a pleasant morning. To a human, handling birds is a fascinating and rewarding experience. It’s hard not to be emotionally affected, even if in a restrained and professional way, by the physical fact of a live bird in your hand. Feather to skin, a bird’s warmth, heartbeat, and softness transmit themselves directly to you in a way that can feel electric.
To a bird—there’s no getting around it—a ringer is a predator.
Having said that, most of the birds we trap are likely to have what are obviously far more dangerous encounters with actual predators every day. Many are migratory species which travel thousands of kilometers each year and face the most grueling environmental conditions. Birds are by constitution tough animals, capable of weathering stress—especially if it is temporary and causes no physical injury—very well.
I will not lie to you. The risk of physical injury does exist. But I believe it is safe to say that the overwhelming majority of the millions of birds ringed annually, under the supervision of ringers licensed by their home nations, emerge from the process completely unharmed.
If I had written this post a few months ago I wouldn’t have been able to make that statement as confidently, but thanks to a recently published study, beautifully unpacked here by a science writer I respect a great deal, I can tell you that when the records for over 600,000 mist net captures in the United States were analyzed, the average rate of injury (which includes events like wing strain, cuts, stress, or broken bones) was found to be less than 0.59%, and the average mortality rate about 0.23%.
While those numbers are extremely low, they would still represent an unjust harm to bird populations if ringing served no useful purpose. But it serves many—too many, in fact, to describe here in detail, especially since I am quite sure you are now, like me, entirely out of cookies and tea (I switched to tea a little while ago).
Here then—highly abbreviated—is a short list of scientific and conservation-related reasons birds are ringed:
• Ringing is the primary method of understanding bird migration. (Before the advent of ringing as a systematized process, migration was a deep and myth-producing mystery.) By recovering previously ringed birds at different points on their migration pathways, we can identify important nesting, wintering, and feeding grounds, and note changes in routes. Such knowledge is not only interesting for its own sake, but an important advocacy tool for conservationists seeking to preserve habitats or demonstrate the effects of human activity or global warming on bird populations.
• Ringing is the only way to gather data on the lifespan of individual birds and thus establish longevity records for bird species in the wild.
• Ringing and recapturing birds in the same site over a sustained period can enable us to roughly determine how many birds exist in a given population, as well as how well they are surviving and breeding. Ringing can also help to pinpoint the reasons for population changes. For instance, if a particular species is becoming rarer, but we know from nest box studies that it’s successfully nesting and raising chicks and we know from mist net ringing that the rate of juvenile survival has gone down, then we know that some condition affecting young birds, but not affecting adult birds’ capacity to breed, is responsible for the population decline—and we have a better idea of where to look next.
• Ringing game birds is vital for monitoring the impact of hunting and determining if existing regulations are effective or should be changed.
As I write, I can feel the cool contours of my own ring embracing my finger. Beyond its shape it bears no other resemblance to the small aluminum or steel bands we put on birds, except for one: both represent a promise from those who put them on.
Of the promise that was made to me, nothing more need be said. I appreciate it every day.
Birds, of course, have no such feeling about the promise their ringers make to them. But I believe it exists, despite this, in the closing of each circle around each protesting leg. To me it seems at heart a very simple vow: to know, to heed, to protect, to remember, and to look for again.
July 16th, 2011 | Meera
The Science Essayist is volunteering at a bird observatory in Sweden this summer.
Since I had it ever-so-subtly pointed out to me today by a good Swedish friend that I had not—despite my promise to spend the summer writing—made a new post here in what was deemed too long a time, I hereby make the following solemn pledge to you all.
Come back in a few days, and I will tell you a little bit more about the steps that go into processing a bird that you catch in a mist net, the physical act of ringing, and what it’s been like for me to handle live birds. I hope that will satisfy. :)
In the meantime, in case you haven’t been following the journey on Flickr, I have this for you, too. Don’t we all feel like this sometimes—capable of crossing the world on our wings, if only something weren’t holding tightly to our feet?
June 12th, 2011 | Meera
The Science Essayist is volunteering at a bird observatory in Sweden this summer.
I’ve never believed my hands were particularly nice looking. When I was 12, I was envious of the long, slender fingers on my friend Beth. You couldn’t really hope to be an artist, I thought, without the right pair of hands. Either you were born with both the temperament and the digits—which, according to all the Jane Austen and Lucy Maud Montgomery novels I was reading at the time, arrived together—or you were doomed to a prosaic life.
I’ve also never believed my hands were particularly strong or skilled. When I started volunteering at the Field Museum two and a half years ago, it was the first time in my life that I’d really done anything useful with them. But that work, satisfying as it is, didn’t do much to transform my hands into Tom’s hands—which I watch whenever he’s working on a study skin or a taxidermy mount in the lab. Tom’s hands perform the most deft and precise motions. Yet they’re also large, callused, and muscular, and marvelously capable looking. They’ve been out in the world.
A week ago, I returned to the observatory from a long afternoon of tracking. I had just fallen from my too-tall borrowed bicycle onto a dirt and gravel road while speeding downhill, and I was feeling particularly incompetent as I walked into the yard, brushing at my bleeding lips and forehead. There I found Jennie—who grew up here in the Swedish countryside—out by the shed, fixing the bottom of the observatory’s power boat by nailing wooden planks together. “You can do anything,” I told her, meaning “I can’t.”
My hands don’t know as much as Jennie’s. They haven’t built many things, or used many tools, or been trained to keep me alive when the world goes all to hell. They’re nice hands and all; they’re just not very experienced.
Or they weren’t until now.
For the past two and a half weeks, my hands have been busy carrying field equipment, helping me push my way through birch branches and willow trees, reaching out for balance on rocks, brush, and muddy ground as I stumble up and down mountainsides, wielding rakes and paint brushes, hauling stones, helping to pull a boat by its rope, measuring and cutting wood, and—today—building an owl-sized nest box with a hammer, nails, and a great mess of splintery wooden planks.
And do you know what? Small signs of change are showing themselves on my hands. They’re a little scratched up. They’re dry and rather rough. They’ve got some cuts and scrapes and blisters on them, and a good amount of dirt seems to be baked into a couple of my fingerprints.
My hands still aren’t Tom’s hands, or Jennie’s. They’re definitely not getting any more artistic. But they’re engaging with the world in ways they’ve never done before. And I like the way they feel.
P.S. Here is the nest box I made today:
And here is the Great Snipe nest I found, a few hours later, hands on my antenna.
June 10th, 2011 | Meera
The Science Essayist is volunteering at a bird observatory in Sweden this summer.
I keep making mental notes about things I want to tell you, and then finding that it is suddenly midnight and I don’t have it in me to write about the ferocity of lemmings, how it is possible to hear water levels changing, why I forgive the mosquitoes their pursuit of me, what almost-fledged nuthatches sound like when they are frightened, or the way you can see rainstorms coming for hours in the sky before they actually let fall their first fresh drops.
More on these subjects later. For now, I wanted to pop in to tell you one thing:
There is at least one Great Snipe here in the mountains with the grounds to take out a restraining order against me.
Convinced she had a nest and determined to find it, I spent an inordinate amount of time today tracking and flushing, tracking and flushing, tracking and flushing the poor creature, looking each time for that longed-for circlet of dried grass containing a clutch of four perfect mottled eggs. I never saw any such thing in the locations from which she scissored herself up when I came close.
Johan has already found seven such treasures, so it’s clear that some birds are currently nesting. But after having observed that this particular female (transmitting on channel #20 on my receiver) was never found in exactly the same spot twice, I concluded that she probably hadn’t actually built herself a nest yet. I’ll go back to that spot in a few days and check again, and hopefully by then she will be well on her way to motherhood.
In the meantime, I’ll do a little penance in my head for harassing her so today.
May 2nd, 2011 | Meera
There is a little weather station on the University of Chicago campus, but it’s been out of service for the past couple of weeks as a result of the interminable construction they’ve been doing up on the roof of Ryerson. (Ryerson is the building whose roof also houses the telescope I told you about here.)
We in Hyde Park who rely on the neighborhood-specific temperature and wind-chill readings the weather station usually provides were quite bereft. But as of tonight, University of Chicago Weather is back up and running—and because I happened to attend the work night the astronomical society had scheduled for today, I got to help return it to action.
Specifically, I put a new battery in the weather station and held it for some minutes in my arms—like a tall and unattractive dancing partner, all bones and wiry hair and no conversation skills—before handing it to two others (more intrepid than I) who carried it up an incredibly long ladder to the top of a turret and reinstalled it.
I feel like I have touched greatness. Oh; and it’s currently 42 degrees out in Hyde Park. In case you were wondering.
April 7th, 2011 | Meera
I continue to spend Thursdays in the prep lab. While I’m there each bird represents a small, self-contained mystery. What species is it, and is it new to me? Where did this particular individual come from—the collision monitors, a rehabilitation center, a museum security guard who saw something on the path outside and brought it in? How did it die? Was it healthy and well-fed on its last day? Was it young or old? I can answer most of these questions as I go along, using the bird’s outer (and inner) appearance and the information on its tag.
I also like to think about the bigger mysteries the Field’s specimen collection is designed to help researchers answer. How do bird populations change over time? Which ones are increasing, and which decreasing? Are migration routes and timings affected by global warming? Can we see evolution at work in the shape of a wing, or a bill, or a foot, if we go back far enough?
Sometimes, though, I get a glimpse of medium-sized mysteries: curious, spontaneous questions raised by the specimens themselves.
In late September 2009, on a stormy night in Minnesota, hundreds of birds from a wide variety of species flew into a tall structure—a telephone tower or something like it—and were killed. The dead made their way, via the Minnesota Department of Natural Resources, to the museum. And eventually, after a long rest in the freezers (we’re behind on specimen preparation), Dave began taking them out for processing. When that happened, he noticed a strange thing. If birds of those particular species had been found at that time of the year in the Loop, the vast majority of them would have been juveniles. But the Minnesota birds were almost all adults, with fully ossified skulls and well-developed gonads. This held true over the entire range of birds (which include sparrows, warblers, thrushes, grosbeaks, and ovenbirds, just going by what I’ve personally prepared).
Why would this be the case? Dave says that for now, he truly has no idea. So he’s working on collecting data about the entire group of specimens, and while he’s doing so he’s talking to his colleagues and trying to formulate theories that could explain this strange occurrence. Eventually, they’ll either come up with a brilliant explanation, write a paper about it, and let everyone in the community know, or they’ll remain stumped, write a paper about it, and invite everyone in the community to help figure it out. It seems like a pretty wonderful process: an example of the way science is supposed to work.
At some point in the day today I was looking for the box of yellow pins we use to fix study skins to the foam boards on which they dry, and it turned out Dave had spirited them over to the sink. When I got there I discovered that he was sitting in front of a giant tray of American woodcock carcasses, opening them up, and—if they were female—pulling out their ovaries and oviducts with a pair of tweezers and pinning them to little pieces of cardboard. Then he was putting them into a jar of formalin.
Why would he do such a thing? Well, it’s like this. The museum has a large number of woodcock specimens, collected as they pass through the area during fall migration. At some point Dave noticed that a lot of the female woodcocks had very large and well-developed sexual organs—a characteristic typically associated with the height of mating season. A few of them actually had eggs that were at the yolking stage. I saw one that was clearly yellow and as big as a large marble! Maybe, he thought, the birds were mating as they migrated. (An unusual behavior, worthy of study.) Also, he had a vague memory of someone, not a full time museum staff member but a scientist who’d passed through the lab, having been interested in a question like this—years ago.
So Dave decided to preserve the ovaries and oviducts of all the female woodcocks in the division’s freezers, against the event that that person—or someone like them—would eventually want to check the organs for sperm. He only regretted that he didn’t have the time or space to put them in liquid nitrogen so that the DNA they contained would be preserved. This would allow the future hypothetical researcher to also ID the sperm and find out if the females were mating with different males on different nights of their migration route. As it was, pinning out the ovaries took him hours (and was absolutely fascinating to watch). I made him let me take a picture.
Medium-sized mysteries: maybe their answers will be of great scientific import; maybe they won’t. But it’s fascinating to see them appear without anyone even looking for them, like bits of flotsam washing up on the shore.