Virtual Science Café: Planes, Parasites, and Paleontology

Webinar – Virtual Science Café: Planes, Parasites, and Paleontology
March 15, 2022

Naimah Muhammad:
Hello, everyone. Thank you for joining us. I know we're all getting settled, but we are so excited to kick off tonight's event and welcome you to today's Virtual Science Cafe, presented by Smithsonian's National Museum of Natural History. My name is Naimah Muhammad. I am one of the public programs coordinators at NMNH. And I am a curly haired woman with a gray sweater sitting in front of a white wall with a plant in my background.

Amanda Sciandra:
And I'm Amanda Sciandra, also a program coordinator at Natural History. I'm a brown haired woman wearing a green sweater sitting in front of a full bookshelf. And on your screen is the name, date and time of our program. Along with the images of our three speakers. Naimah and I are delighted to be your host for this event. We are so excited to kick off another season of Virtual Science Café with you and our powerhouse lineup of scientists. For the next three months, we are snacking on a veritable knowledge buffet of natural history. We've got volcanoes, hobbits, coral, fossils, birds, bats, parasites, and more. Can't even wait.

Naimah Muhammad:
So amazing. And the best part is our virtual cafe is not bound by the laws of space and time. We are united by science from all over world. So let us know where you are watching from, by typing it into the Q&A box now, let us know. And we can't wait to see where you're tuning in from. And we'll take a moment to thank those who made this series possible. So first off, our science cafe series was developed with science communication resources, generously provided by NMNH board member, Edward Warner.

Amanda Sciandra:
Our sincere thanks to them for making this possible and to all of those who support the museum's mission and outreach. And thank you to all of those who are here tonight. We have someone from Albuquerque, New Mexico, Lake Placid, New York, Fort Worth, Texas. Whoa, someone from East Sussex in the UK. This is so exciting. Tennessee, Massachusetts, Virginia, Maryland. Thanks for coming.

Naimah Muhammad:
And I'm over here in Los Angeles. So welcome all. We also want to thank DC area restaurant, Busboys and Poets, for being a restaurant partner for this season and for last season. So for those who are local, I hope you were able to place an order using the special discount code or no matter where you are, that you were able to shake up a cocktail or mocktail with their special recipe, which we'll be sending again. And we will look forward to for future programs in this season.

Amanda Sciandra:
So before we turn it over to our guest, just a few standard housekeeping notes. We have three incredible speakers who will present back-to-back lightning style talks, and then answer your questions during the second half of the hour. And that Q&A goes by so quickly. So please help us answer as many questions as possible by submitting your questions right after each talk just as you have them. Again, that Q&A box is located on the Zoom interface on your toolbar. Finally, closed captions are available by clicking the CC on the Zoom toolbar.

Naimah Muhammad:
Awesome. Okay, so let's get going tonight. We're talking bats, birds, and bones. Our first speaker, Dr. Kelly Speer is here on camera with me. Hi Kelly.

Kelly Speer:
Hi.

Naimah Muhammad:
Hey, thank you so much for joining us tonight. Dr. Kelly Speer is a research scientist here at the National Museum of Natural History. She is in the department of invertebrate zoology, and in the Center for Conservation Genomics at the Smithsonian Conservation Biology Institute. She's an integrative integrative biologist who uses ecology, evolution and computational biology to study the interactions between host, parasites and microorganism. AKA, her research reminds us that some of the tiny things we sometimes think of as gross or harmful, actually have an incredible role to play in ecosystems. So Kelly, with that, please take it away.

Kelly Speer:
Thank you very much, Naimah. When I tell people what I work on, which are bats, parasites, and microbiomes, I often get a look of disgust or curiosity. Why would I study so many things that have such a bad reputation? But I'm here to convince you that not only do these things have this undeserved bad reputation, but they actually do a lot of good for healthy ecosystems, and for us. So most of the time when people think about bats, they automatically think of the bad things that they've heard. For example, bats can host viruses and other pathogens. One of the reasons that bats can host so many viruses and pathogens is in part because they roost in these really large colonies. Like you see in this picture on the top of your screen. These colonies can be tens of thousands of individuals. So there's lots of opportunities for transmission of viruses.

Bats are also the second most diverse group of mammals. So just after rodents, bats have the most species of mammals with about 1400 species of bats. And this diversity means that a lot of pathogens have been able to diversify within bats. So the more species there are, the more pathogens there are too. People also typically think that most of these bat species feed on blood, like the common vampire bat that you see in this video feeding on cow blood, but actually only three out of 1400 species of bats feed on blood. Most of the bats actually feed on insects. There are also fruit eating bats and pollen, nectar, feeding bats. So that's the bad stuff that people normally think of, but people don't typically think of bats as cute. This is the bumblebee bat, it's the smallest bat in the world. And it only exists in a few caves in Thailand.

I also want to note that this picture was taken a long time ago, and PPE has really changed in handling bats. I definitely don't want you to get the idea that people handle bats without gloves. And if you find a bat in your house, you should not handle it. And I think we're going to post a link in the chat for what you should do if you find a bat in your house.

Here's another picture of a cute bat that people don't typically think of when they hear that I study bats. This is the Honduran White Bat. This is a tent roosting bat. So they live in small family groups and build tents using palm fronds. They bite along the stem of the palm frond and make themselves a little tent and they roost in there together. So this is as if you are peering up underneath this palm frond to see these bats looking down at you. They're not just cute. They also do a lot of really great things for healthy ecosystems. For example, insect eating bats like this Pallid bat, common in the Southwestern United States seen here eating scorpions, help protect crops against insect pests. In one study of cotton and corn, agricultural pests, it's estimated that bats saved, Mexican free-tailed bats saved farmers, an annual value of over $741,000 a year in pesticides that they don't have to spray.

Similarly, there are bats that feed on fruits. These fruit eating bats are important seed dispersers and because they like to fly along forest edges, they can help deposit seeds of native plants to help regrow disturbed forests. This is the lesser long-nosed bat, Leptonycteris yerbabuenae, and it is a pollen and nectar feeding bat. You can see it's faced totally covered in pollen here. And that's because it's a pollinator of agave and cacti. Actually in Mexico, there is a fungal pathogen that is attacking agave plant used to make to tequila, and farmers have found that by leaving a portion of the agave crop so that it can be pollinated by bats can actually protect those agave crops from this fungal pathogen. So if you like tequila, then you like this bat. And you should definitely look for bat friendly tequila in your liquor store. So those are just a few examples of all the good things that bat do for people and for healthy ecosystems.

So how do I study them? So this is me and this is a super awesome bat. This is the Mexican free-tailed bat, which is really common in the United States. You've probably seen it flying around your house. And the way that I go and look for bats is I spend a lot of time in various holes. So on the left is a hole in the ground in The Bahamas that actually opens up into an inundated cave that has blind cave shrimp. On the right is a different type of cave, that's more of a crevice. And this cave, I didn't quite enjoy as much because all of the orange stuff that you see is actually poop. So I use a combination of methods to catch bats. One is essentially a giant butterfly net with a really, really long pole. Like you see on the left hand side of your screen. The other way is that we set up fine nets called mist nets, in the forest, so that bats flying into the net. We catch them and untangle them.

Once we catch them, we bring them back to a field site. Here, this is an example of one field site that I go to with a lot of other bat biologists. You can see me in the tie-dyed shirt. All of those white bags on the line, on the right hand side of your screen, each one of those bags has a live bat, that's just hanging out. It likes being in its own little space. And everyone going up to those bags and tying flagging tape is interested in studying a different part of that bat. For example, how does it fly? How does it land? What are the dynamics of pathogens in this landscape? For me, I'm interested and learning how we can study parasites and microbiomes of bats to learn more about bats in ecosystems.

So let me tell you a little bit first about bat parasites. The ones that I specifically study are called bat flies. You can see one on the top of the head of a bat and then also a zoomed in picture of a different type of bat fly. Bat flies are obligate blood feeding parasites of bats, that only live on the outside of bats. So they're ectoparasites. Typically, people think of these parasites as harmful or something that we should get rid of, but actually a lot of research has indicated that parasites are also integral parts of healthy ecosystems.

So for example, this horsehair worm emerging from a cricket, also a very common parasite in the D.C. area. It's been found that these horsehair worms, which convince their hosts, they manipulate their cricket hosts to jump into fresh water. This increases the amount of crickets, so food sources in fresh water for things that live in those streams, like fish. And in Japan, horsehair worms have helped save an endangered species of trout by convincing crickets to jump in the fresh water. There's more food for these endangered trout, and the trout we're able to be saved.

So in this way, parasites contribute to healthy ecosystems by controlling energy flow in those ecosystems. Kind of surprising. So how do I use bat flies to learn more about bats? Well, take, for example, the islands of The Bahamas, which are just off the coast of Florida. These islands are split into two big banks, the Little Bahama Bank and the Great Bahama Bank. These are separated by a deep oceanic channel called the Providence Channel. And it's known that bats have a difficult time flying across the Providence Channel, potentially isolating populations of bats in the Little Bahama Bank and altering their conservation status to a more concerning one. So in order to understand how well bats were dispersing across the Providence Channel, we used their associated bat flies. Because bat flies have faster generation times than their host, which means they lay a lot more eggs. And so they have a lot more turnover in their generations. They can be a high resolution tool for understanding population genetics of their host.

So by looking at the dispersal of that parasites across the Providence channel, we actually found that this bat, the Buffy flower bat showed a recent decrease in dispersal across the Providence Channel from the Great Bahama Bank to the Little Bahama Bank. So that indicates that the bats on the Little Bahama Bank are much more isolated than they are in the Great Bahama Bank, potentially increasing their conservation concern. So that's one way that we can use parasites to learn more about their bad hosts. Just to add another layer to this problem, just to show you how complex these systems really are. I also study the microbiomes associated with both bats, and their parasites. So microbiomes are any microorganisms associated with a host or a site.

So in this case, I study the bacteria associated with bats and their parasites. The reason I do this is because some of these members of the microbiome can be harmful. For example, White-Nose syndrome is a fungal pathogen, that's affecting that bat populations. Starting in the Northeastern United States in these blue and purple colors, and then spreading throughout the United States, indicated in these red and yellow colors. This fungal pathogen causes declines in bat populations. And it's been found that the bat skin microbiome can determine the susceptibility of a bat to this fungal pathogen. So in order to examine where the bacteria on the bat skin comes from, I swab the skin of bats from these sites in Mexico. And I also characterize the microbiomes of the caves that they were roosting in and of their associated ectoparasites. So you can see a schematic of the swabbing and sampling on the top left.

What I found is that the microbiomes of caves indicated by this trapezoid and bat skin are pretty similar. So the colors in these different bars represent different bacterial taxa and their relative abundance in different sample types. So the bars here each represent a different sample type and the colors indicate different bacteria. You'll notice is that the trapezoid representing the cave microbiome is very similar to the skin microbiome. This indicates that the bat skin microbiome may actually be determined by its cave environment. So instead of bat skin being the important factor in determining susceptibility to White-Nose syndrome, it may actually be the cave that's the most important factor.

So that's just one example of how we use microbiomes to learn more about parasites and their bat hosts and how we can apply that to understand healthy ecosystems. So this is a picture from Rock Creek Park in DC. The next time you're in nature and you see an animal or a plant, I hope you start to think about the microorganisms or parasites that are also associated with that host and how the complexities of life actually contribute to that healthy ecosystems that we see. Thank you very much.

Amanda Sciandra:
Thank you so much, Kelly. I don't know if I'll ever get the image of the little parasite on top of the bat's head, out of my own head, but I do very much appreciate the extra info. Thank you to everyone who has already submitted your questions. Keep them coming. We'll get to as many as we can after our third speaker. Our next guest is Dr. Sarah Luttrell because of the breadth and depth of the Smithsonian collections. There are unique research opportunities for scientists who utilize those shelves and drawers and stacks and jars. Like did you know there is a lab here that uses DNA and feather specimen to identify snarge? But what the heck is snarge? Here to tell us that and more, is Dr. Sarah Luttrell. Sarah has been studying feathers in one form another for nearly 20 years. She is currently a research assistant in Natural History's, Feather Identification Lab. And if you don't know that was a thing you soon will. Fun fact, her favorite birds are crows because of their amazing social behaviors. Sarah, the floor is yours.

Sarah Luttrell:
Thank you, Amanda. Did you know that every day the FAA handles on average 45,000 flights in U.S. airspace? And those planes, they're often taking off and landing in habitats that appear like green oasis in a human dominated landscape. But planes aren't the only thing in the air. There are also more than seven billion birds in north America, sharing the air with us. And so it may come as no surprise that sometimes those planes and birds collide. In fact, in 2019 alone, the FAA reported 17,228 wildlife collisions. That's an average of just more than 47 strikes a day, and most of those collisions are birds.

So you'll be forgiven for feeling like this is probably not a big deal. After all the difference in size between a commercial airliner and a songbird is so fast that it's basically analogous to you hitting a bug in your car, driving down the highway. And just like that bug makes splat on your windscreen. That bird makes a splat on the plane. Something that industry refers to as snarge, which is a word that is created from a combination of the word snot and garbage. Basically the verdict that's left behind after a collision. Most of the time, these collisions are no big deal. The flight crew, the passengers, nobody's even aware that it happens. They find the snarge after the fact. So you might be thinking, well, it doesn't matter to me what kind of bug gets smashed on my windshield, why should we be interested in what kind of bird created snarge? Well, it turns out there's quite a number of people for whom that information is really valuable.

The first example are wildlife biologists. So it turns out there are wildlife biologists at nearly every major airport in the United States. And the job of those people is to keep wildlife out of the way of planes. If the biologists know what animals are getting hit by their planes, they can recognize patterns and they can do things basically like the opposite of habitat conservation, to make the habitat in and around the airfield, as repugnant to those birds as possible to keep them away. They can also work with surrounding land uses nearby the airfield. So it turns out since airports are often located on the margins of cities with other land uses that people don't really want in their backyards, say like a dump, that there are often animals attracted to those surrounding land uses as well. And if biologists can identify an animal that's being hit on their airfield, as one that is frequenting some of these alternative land uses, then they can work with managers, say at that landfill to try and reduce the number of animals on the landfill and get them to disperse.

But it's not just biologists who care about this. Engineers are also really interested in what kinds of species are getting hit by airplanes, because a major part of their job is to make sure that those airplanes can withstand the impact of particular sized animal and still operate safely. So knowing the species is really important for them to maintain efficiency and safety. Because sometimes these collisions aren't minor. You might remember a few notable examples like in 2020, when vice president's Pence's plane hit a duck during a campaign stop, and had to make an emergency landing. Or just a few months ago, when a Spirit airline sucked a Bald Eagle into the engine on takeoff and the engine burst into flames on the runway. Or most famously flight 1549, which ingested Canada geese into both engines, leaving JFK airport and had to make an emergency landing in the Hudson River.

And whether those collisions are minor or major, whether they just involve wiping off a smear or hoisting a plane from the bottom of a river, each of those samples finds its way to a special lab at the Smithsonian Institution, National Museum of Natural History, Feather Identification Lab. Snarge started coming to the Smithsonian in 1960, after a fatal crash in Boston, Logan Harbor. At the time Smithsonian research associate Roxie Laybourne was a world expert in feather microstructure and morphology. It turns out that each feather on a bird has Downy parts near the body that have characteristics unique to a particular family of birds. And Roxie was a world expert in identifying these characters. She was able to identify the species involved in that Boston crash as a European Starling. And from that point forward, Roxie became the go-to person for bird forensics. From her [dogged 00:21:43] start in 1960 to today, the lab has grown to a team of five research assistants headed by Dr. Carla Dove. And we identify more than 10,000 cases a year.

We use a variety of tools, DNA analysis, Roxie's microscopic analysis. And sometimes we simply wash up the feathers and take them out into the collection to match them up to animals that are out in our collection. And sometimes we uncover some real mysteries. For example, late in 2021, we got this hunk of skin and feathers that arrived from inside the engine of a plane that had just flown from Chicago to China. Initial DNA analysis identified the bird involved in that collision as an Anhinga, which is a diving bird native to the Southeastern US, Central and South America. So we have a little conflicting evidence here, an Anhinga does not belong in China, and it does not belong in Chicago, but it was in the engine of this plane. So just to double check ourselves, we checked the microscopy and we checked the whole feather and indeed all of our lines of evidence say, Anhinga.

So we got together with collaborators at the USDA and were able to track that flight back. And it turns out previous to the Chicago leg, it had been in new Orleans, Louisiana, which is within the range of Anhinga. So we've solved our mystery. This animal was struck in new Orleans and the plane carried the remains of it on from Chicago, and then finally to China. And now that we know this species identification, that engine manufacturer removed the engine from service due to the size of the animal hit. And the wildlife team in Louisiana is able to add another line of evidence to help them in their wildlife management plan.

So if you'll allow me, this part of my job is so cool, I could talk it all the time, but if you'll allow me, I want to pivot right now and talk about something that I don't often get to brag on about our job. And that is, why the Smithsonian is uniquely positioned to identify the country's snarge. Well, the bird collection at the National Museum of Natural History has over 500,000 study skins representing 85% of the world's bird diversity. That's an enormous reference library. And it's exactly what we need to do our work because, just in FAA flights alone, there have been more than 600 species identified in wildlife collisions. But it's not just the diverse of species we need to do our job. We also need multiple individuals representing each species. Birds can vary dramatically in their color or their size, depending on their sex or the time of year in which they're collected. And you can see examples of that here in these Tanagers, on the left and the Cooper's hawks on the right.

And just as you could never choose a single person to represent the diversity of the human race. You also can't choose a single bird to represent the diversity of its entire species. Each of these 21 specimens shown here in this picture are song sparrows, common backyard bird found throughout North America. But the birds in the upper left, those were collected from coastal Alaska. While, the ones in the lower left are from the desert Southwest. And you can see the difference in size and color between them. But whether we get a sample from JFK, in New York or Minot, North Dakota within the Natural History collection, we've got birds that represent the local population that can aid us in that identification.

And it's not just the morphological characters of these specimens that are useful for us. They can also be the source of genetic vouchers. We can sequence their DNA and use it to compare to bird strike samples. And that's not only useful for us, but those DNA sequences, we also publish them publicly so that they can be shared with scientists around the world. And this is something that still blows my mind a little bit when I'm out in the collection this is a bigger shot of that image I showed you before, when we were looking at using a whole feather to compare to a specimen. And I want to zoom in here on the tag on this specimen. This tells us the information about this particular animal, when and where, and how it was collected for the museum.

This happens to be a Greater White-fronted Goose, and it happens to have been collected in 1885, 8 years before the Wright brothers would achieve the first powered flight. The scientists that put this bird in the collection could have never imagined how I would use this specimen. At the time that they collected this goose airplanes didn't exist. Commercial air travel was something they couldn't imagine. And they also did not understand the form or ability to sequence DNA yet. And yet every day I can go out and to use these collections regardless of the age of the specimen in order to make species identifications and make sure that your next flight is very uneventful.

Naimah Muhammad:
Wow. Thank you so, so much, Sarah, I definitely for feel safer traveling by plane now that I know what snarge is and about the work of your lab and lab at the museum. So thank you so much. And we already have great questions coming in, so I'm looking forward to diving in later. Okay. So we started the evening with Kelly who showed us how researchers at Smithsonian are studying live bats and microorganisms to understand ecosystems and the emergence of novel diseases. Then, Sarah showed us how a specimen collected in 1885 can be used to solve aviation mysteries of today. Now we wind the clock back even further, back into the deep time fossil record to see how Smithsonian scientists are still learning new things about how ancient fossils came to be.

And here we have that field of study, which is about how living organisms turn into fossils, which is known as taphonomy. And who better to tell us about fossilization than the mother of taphonomy herself. Our last speaker of the evening is Dr. Kay Behrensmeyer. Hi, Kay. Kay is a paleontologist and geologist who has pioneered the field of taphonomy, and studied land environments and animals through geological time with a particular focus on human evolution in Africa. Kay, is a curator of vertebrae paleontology and is the deep time lead scientist.

And if you are familiar with a Deep Time exhibit at the National Museum of Natural History, you know how cool her job must be. And if you're not familiar with the Dino hall at Natural History, Kay has shared some resources in the Q&A for you to check it out later. Kay is a member of both the national Academy of Arts and Sciences and the national Academy of Sciences, one of the highest honors in the scientific field. Wow Kay, I just feel so honored to be with you tonight. She's also been a mentor and advocate for early career scientist and women in STEM. And what better way of celebrating women's history month. So without further ado, we welcome Kay Behrensmeyer for our last talk, before we open up to your questions. Thank you, Kay.

Kay Behrensmeyer:
Thank you so much Naimah for that wonderful reduction. I'm really happy to be here and happy to share my enthusiasm for fossils. And a story that I'm going to tell about how my assumptions, about how to become a fossil have really been changed by some of my research. We all know a little bit, I think about fossils and most people think if they wonder how they form, well, it must take a long period of time. And that's what I thought too, but you'll see, I was actually wrong about that. So how did my fascination with deep time in the fossil record begin? This is a picture of me when I was four years old growing up in Western Illinois, and my mother's getting me ready for a trip to the farm, where we didn't live on the farm, but we'd go there on weekends would look along Pigeon Creek and we would find fossils.

And this is the kind of fossil that started to get me interested. These are very ancient. They're marine creatures. There are no bones that I ever found on the farm. But nevertheless, they made me very interested and curious about the past. And then my parents and my aunts gave me books that I could read about walking with dinosaurs and looking at pterosaurs in the air. And it all just turned into a wonderful start for a career of trying to figure out more of about fossils, and as a kind of time machine. And this is in a way characterized by this wonderful artwork where you can imagine yourself, and I imagine myself looking into rocks, trying to understand what happened to make these creatures become fossilized and what they meant. And you can see in your imagination, there are waves washing over these sea creatures. But when you look into the rocks, one question always occurred to me, because often you don't find any fossils. Why is it hard to become a fossil?

Well, as I grew up and I found out more about biology, I realized that to become a fossil, you need to escape being recycled ecologically. If you look at this diagram, the sun provides energy to grow plants and then consumers like herbivores, eat the plants and carnivores eat the herbivores and so on. And it goes around in a cycle and all those nutrients, all that energy has to somehow be returned to life as well. So, that's what happens to most organisms. They get recycled. Those that have hard parts like shells and bones, it's a little bit harder. And sometimes it's important to be buried quickly, that can help as well. So you can even get feathers and leaves that are not full of hard parts, preserved in deep time. But most fossils in order to survive over long periods of time, have to be turned to stone in some way, and especially this applies to bones.

So this is a view of buried bones and the arrows show that minerals are seeping from the soil into the pores in the bones, about 35% of usual bone is pore space. So when those minerals go into those spaces, then that starts to make the bone turn to stone. It becomes heavier. So this is what we call precipitation in bones. And one of the questions is how long does it take? Most people would say a long, long time. And that's what I used to think as well. And why does this matter? Well, fast mineralization conceal and preserve original bone mineral. And original bone mineral can tell you something about the animal as when it was alive, and even what it was eating and where it lived. But slow mineralization gives time for processes called biogenesis to replace the original biominerals. So that's shown here, and it can even destroy the original structure of the bone. So fast is good. Slow is not always bad, but often it is, for that original information.

So now I'm going to switch into a pretty complicated diagram, but this is what Naimah was saying. Taphonomy is a study of how organic remains go from the biosphere to be preserved in the rock record. And there are lots of different pathways here. It looks pretty complicated. If you take a wildebeest, that's alive, it ends up as a dead wildebeest before, too long, years, often it then is sitting on the ground as a skeleton. Parts get preserved or not in the short term, but most of it is going to go back to feed other Wildebeest in the biosphere. And not much is going to make it over into the rock record to be a potential fossil. Well, I wanted to study more about this in an actual ecosystem.

So when I was able to organize these kinds of projects, I went to Southern Kenya near Mount Kilimanjaro. And here I'm looking at an elephant skeleton, wondering, and trying to record what parts of it might end up buried and as potential fossils. And I don't do these projects by myself. This is just a quick look at some of the wonderful people that I've collaborated with to do surveys of bones in Amboseli. So what we found is that bones disappear, of course. They're eaten by predators and scavengers like these hyenas, which consume and digest everything and their feces just consist of bone powder, basically. If they are not eaten by hyenas, bones weather away over tens of years. And I've collected these ribs over a whole series of years from the same cow, and you can see by 1985, they're just a pile of fragments except for the one on their far right, which actually got buried in, only an inch or two down, but that helped to preserve it. At least for the short term.

Other bones can be consumed by microbes. This is a rhino skull that we looked at in 1975. In 1985, I took a thin sec, or took a piece of it and made a thin section, a micrograph. And the gray areas are still the original bone, but the brown areas are where the microbes are starting to destroy it. And if left for a number of years, it would be totally gone. Some bones are buried in swamps or in ponds, in Amboseli as well. So you'd expect that those would be perhaps potential fossils. But in all of our surveys and counting up thousands and thousands of bones, we found that 96% of them are going through the process of being recycled, and only 4% are even making it into the shallow buried environment. And we couldn't really dig up and look for things that were more deeply buried.

So we didn't really expect to find out anything about the process of mineralization, because as I said, it's supposed to take a long time. Well, that's where I found out something surprising. I picked up this toe bone of a Wildebeest, and when I picked it up, it was unweathered in very good shape, but it was strangely heavy. So I thought, Hmm, this is weird. I collected it. I brought it back to the museum. I made a thin section of it and was really surprised to see. And you can see the cross section on the right. And the enlargement is a micrograph on the left, that there were these yellow minerals filling in some of the pore spaces. Well, that is calcium carbonate. And even though this bone was not weathered, and it was lying out on the surface, it had started to fossilize. It had started to turned to stone before it was even buried.

And that made me remember and go back to my notes that I had found it in this, what we call pan or a dried up pond, where there was seasonal water and that water had a lot of minerals in it. And when it dried up, the minerals got precipitated in the bones, including that toe bone. So if we go back to this diagram and recall what should have been happening to that toe bone, this is what we knew before. That is, it would, especially a small bone like this, it would go into the organic remains. It would go onto being exposed and disintegrating, and then being recycled, like 96% of the other bones in our surveys. So this is actually the source of a new hypothesis, a fast-track to fossilization. So in this case, the bone mineralizes and then moves into the potential fossil record. It's more durable, it's tougher for the recycling agents to destroy. And it has a better chance of becoming a fossil.

Here's a reminder of those minerals that have partially filled the pore spaces. And the remarkable thing is that this happened within a few years, not over a long period of time and not even in the burial environment. So the next time you go to a museum and you have an opportunity to touch a specimen of a real bone, here's a Brachiosaur humorous that's part of our new exhibit at the Natural History Museum. You're touching that bone and you're thinking how huge it is and the animal that once had that bone. Now, we can also imagine that because inside this bone, there may be original biominerals from that dinosaur, you're actually touching a part of that dinosaur that was walking around when it was alive.

That's pretty special. It shows that there's always more to find out about the fossil record and that in this case, we might even be able to reconstruct more about what that animal was eating, and compare it with what other animals are eating by the composition of that original biomineral. So back to this wonderful diagram, I just want to leave you with the thought that there's so much more to find out about fossils. And I hope that some of you will do that. Thank you.

Amanda Sciandra:
Kay, thank you so much. Next time I'm in the museum, I will think of that Brachiosaur bone differently now, with new eyes. And thank you to Kelly and Sarah as well. Let's welcome everyone back on screen. Fabulous, because we have some audience questions to get to. Our first question here is for Kelly. Kelly, max wants to know what's the significance or relationship between the bat skin microbiome and the parasites?

Kelly Speer:
Yeah. So I didn't get a chance to cover it during this talk, but it seems that the microbiome on bat skin and even the oral microbiome of bats can release volatile, organic compounds that the parasites can use to locate their host. So that's one hypothesis about why bat flies are so specific to one species of bat.

Amanda Sciandra:
Fascinating.

Naimah Muhammad:
Crazy. Okay. So we're going to move, we have so many audience questions. So Sarah, I'm going to throw one your way. And it's a question from Alice who wants to know, are there any other labs that do the sort of forensic work in other places around the world, or is the Feather Lab at the Smithsonian unique in this regard?

Sarah Luttrell:
Yeah, that's a great question. So it turns out there's actually an enormous network of people who are interested in wildlife strikes, and there are many countries that have their own wildlife forensics identification teams. So we are not unique globally, but we are rather unique in the United States. We do this for the US, for birds strikes, and there's also a lab out in Oregon, the US Fish and Wildlife that does this for wildlife trafficking and wildlife forensics as well.

Amanda Sciandra:
Super cool. All right, this next one is for Kay. Kay, Mike wants to know what are the sweet spots in terms of years for DNA and radiocarbon dating analyses?

Kay Behrensmeyer:
Oh, that's a great question. And it's quite variable depending on the environment, but for DNA, preserving original DNA in the best circumstances where you don't have oxidation, you have quick burial. I think the most time that anyone has been able to find intact DNA or pieces thereof, is less than a million years. So the DNA is just, it's really fragile. And even though we all... Jurassic Park is in everybody's minds as a possibility, we may not have found the sweet spots that really preserve much more ancient DNA. And for Carbon 14, the maximum amount of time that you can really get out of that is about 30 or 40,000 years because of the decay rate. And after that, you don't have enough left in the bones or the tissues. But if you can get enough tissue, you can get back that around 40,000 years, with special methods.

Naimah Muhammad:
That's amazing. And I think there's a few questions related to that. So we might come back to a few of them, because the audience really want to drill in that answer. But we have a question here to Kelly now from Diana, who is asking if you can clarify whether or not you've studied different kinds of caves that serve as roost for bats? And if so, the difference of bacteria in cave variations? And she referenced, for example, her research group found different bacteria on bats in carbonate caves versus gypsum caves. So wondering if you've seen this in your research as well?

Kelly Speer:
Yeah. Thanks to that question, Dr. Northrup nice to hear from you again. I hope you're doing well. Yeah. So, that's a great question. So the population of bats that we studied is migratory. So we were essentially tracking their skin microbiomes as they were migrating northward, annually in Mexico. And they are roosting in different types of caves, but most of them are karst limestone. So the stone composition of the cave is not different, but they had variable light exposure and humidity and temperature. So potentially the bacteria could be impacted by those environmental things or by the stone composition, but we didn't have the opportunity to measure the impact of the karst limestone on the bat microbiome.

Amanda Sciandra:
Fascinating. Fun that you knew who the question was from. It's good to have fans in the audience. Okay. Let's see this next question, Sarah is for you. When during a flight, does a bird strike or bird strikes usually happen and what's the highest altitude strike?

Sarah Luttrell:
Yeah. So most strikes happen during takeoff and landing. I believe it's something like 70% occur below 500 feet and within 10,000 feet of the takeoff spot. So you can think of it like a bubble around the airfield as the highest risk zone. But strikes do occur far away from the airfield and also at higher altitude. And the highest altitude strike that has ever been recorded was actually at 37,000 feet. Which is, and it occurred off the coast of the Ivory Coast in Africa and was a Griffin's vulture.

Kay Behrensmeyer:
Hmm.

Amanda Sciandra:
Griffins vulture. Not the best legacy. But still very cool. I have a quick follow-up for that. Most airfields, they're surrounded by natural landscape. Are there modifications that you recommend to, I don't know... It seems like it'd be a great habitat for birds, but potentially not if they are interrupting flight patterns?

Sarah Luttrell:
Yeah. So that can be a tricky thing for balancing conservation and human land use and safety. Right? And you're right, that often there are wildlife refuges or good wildlife habitat in and around airfields. It's not really our job at the Feather Lab to make management recommendations. We're letting people know what they're heading. And then those biologists are the experts in how to handle that on the ground. But they certainly work closely with folks at the surrounding land uses, including natural wildlife refuges and things to try and reduce the likelihood that birds and planes are in air space at the same time.

Naimah Muhammad:
Awesome. And thanks Amanda, for the follow-up question there. Okay. So I think we've touched on this, but just in case, question for Kay and again, we're coming back to the time. And how you find out how long it takes for a bone to become a fossil. So the question is exactly that, how long exactly does it take for a bone to become a fossil?

Kay Behrensmeyer:
Well, that's a logical extension and I think the questioner, of this whole hypothesis, we need a lot more research to figure that out. We used to think it took at least thousands of years or millions of years, that the change would keep happening. And now that, it's not only this toe bone, but there's other evidence that fossilization can occur very quickly. So I think one way is to look at experimental situations. And I know that fossil wood has been actually produced in the laboratory. So that's one strategy could show us how fast it can happen.

And then maybe indicators in the microstructure of, if we look at fossils, we could say, well, that one must have fossil really quickly, like within years or tens of years. And another one that showed more alteration was a lot longer, but it's going to be challenging. And you could use Carbon-14. And I actually have a plan to do that with some of my bones that seem to be a little heavy, but are more weathered and look older than that toe bone. So it's a work in progress. And I think though that now that the door is open for understanding that it can be really quickly, that we'll find a lot more by using Carbon-14 to help us see how fast it can happen.

Naimah Muhammad:
Amazing. So we'll continue to evolve this story and get more answers as you continue your research. Thank you.

Amanda Sciandra:
All right. Back to you, Kelly. This question is from Ioana. The question is, is there any way to vaccinate bats against, or yeah, for White-Nose syndrome?

Kelly Speer:
So yeah, that's a really interesting thought, so far there's not a vaccine for White-Nose syndrome. And one of the reasons that is because White-Nose syndrome is a fungus. Fungi are eukaryotes. So it's really hard to differentiate their cells from our cells. The other issue is that, so far, we haven't been able to vaccinate bats against any pathogens, in part, because it's just really hard to catch enough of them for the vaccine to make a difference. For example, people have thought about trying to use transmissible vaccines to vaccinate bats against rabies, but we haven't been able to develop that yet. But it would be a really great thing if we could. So really awesome thought.

Naimah Muhammad:
Thanks, Kelly. Sarah question for you. What is the most common bird species that struck and on the flip side, which species causes the most damage to planes?

Sarah Luttrell:
Yeah, so this varies year-over-year, which is one of the reasons that it's really important that our species identification work is ongoing, because populations of birds fluctuate year-over-year and habitats of the airfields might be modified year-over-year, but there are some usual suspects that show up over and over. So last year, the most common birds struck by civil aircraft was the mourning dove, which is another bird that will be common to your backyard. And the top five suspects over the last 20 years or so are mourning doves, killdeer, kestrels, barn swallows, and horn larks. All birds that don't really mind being in human modified escapees and short grass and open expanses of habitat. And then to answer your other question, the birds that are most likely to cause damage to aircraft are maybe not that surprising, but they're large birds. So it's going to be waterfowl ducks and geese cause 28%, give or take, of the damage to civil aircraft. And then after that is raptors, hawks and falcons. And then after that is gulls. And between those three big groups, that's almost 50% of the damaging strikes.

Amanda Sciandra:
Thanks. All right. This next question. We're just, we're crushing it. Thank you everyone who's submitting their questions. Keep them coming. Kay, this one's for you. What can bone minerals tell us about what dinosaurs ate?

Kay Behrensmeyer:
Well, the original bone minerals, if they're still there, actually one of the best place to find them is in the teeth because that has, enamel has less pore space in it, so it has less chance of being altered. But you can use stable isotopes, especially on dental enamel, to get an idea of the carbon and oxygen of the diet of these creatures. So herbivorous dinosaurs that fed high or low and in the canopy of the ancient forests would be expected to have different stable isotope ratios of carbon. And that drank and, or required water at different levels. Maybe they had to migrate and they had some sources of water that had more or less oxygen, heavy oxygen versus light oxygen. That would show up in their bone mineral and tooth mineral. And also strontium in the minerals can tell you whether they migrated into areas that had more or less strontium.

And this is being used as a tool, stable isotope analysis is being used as a tool for all kinds of ancient creatures. But when I started my career, it wasn't at all certain that the original minerals were preserved. So people had to prove that first. And now it's just a standard tool for learning about the habitats and the diets of these ancient creatures. It's being more and more applied to dinosaurs. And it hasn't been applied so much to bone, because of the problems with minerals and alteration of the minerals. So we need to find more of those bones that show signs of having been rapidly fossilized, which are probably out there.

Naimah Muhammad:
And Kay, it's so funny that you mentioned stable isotopes, because we'll actually hear more about that and the study of stable isotopes and learning diet and putting back these pieces, in our talk next month. So that's a plug for a, to be continued conversation coming up in April. But we have time, we're wrapping up towards the end. So before we get there, Kelly, I know you have a few questions for our colleagues here. I wanted to give you a chance to ask some of those.

Kelly Speer:
Yeah. Sorry. I've been typing away in the chat. So yeah. Question for Sarah and one for Kay. Sarah, what is the hardest snarge you've had to ID and why? And then Kay, what is the most amazing fossil you've ever seen and why?

Sarah Luttrell:
Oh man, that's a tough question. Because there's lots of ways for it to be hard to identify snarge. Off the top of my head, the hardest ones to identify are the ones where the sample comes to us via the wrong address. And it gets irradiated, because after the anthrax scare in the 1990s, a lot of the federal government's mail gets irradiated, which is intended to destroy DNA, which means if somebody's sending us a DNA sample, we're out of luck. So sometimes we can actually get enough sequences to piece together a barcode on those. And often we have to really dig and rely on microscopy and some of those tools. So there's lots of reasons it can be tough, but that's the one that comes to mind.

Kay Behrensmeyer:
Well, and the question for me really has me trying to search my memory banks for all the amazing fossils I've seen. But I guess I'll come down on one that my team actually found, the beautiful jaw of an ancient Pterosaur, a flying reptile, in the petrified forest of Arizona. And it just turned up in our fossil lab, and a volunteer was excavating there and we never expected to find it. And it has 11 teeth and it's a new genus and species probably. And it was the first ever found in the petrified forest. So it's not just how beautiful the fossil is. To me, it's the context. It's whether it tells you something new about its environment, as well as about itself.

Naimah Muhammad:
Okay. If I can just sneak in one more question. And Kelly has asked this question, I have to ask it now. Sarah, have you ever found any bats in the snarge?

Sarah Luttrell:
Oh yeah. We get bats in snarge all the time. All the time.

Naimah Muhammad:
Oh no. Well-

Sarah Luttrell:
[crosstalk 00:59:24].

Naimah Muhammad:
... that just shows us how we're connected.

Sarah Luttrell:
Yeah.

Naimah Muhammad:
Fascinating. Well, this concludes our program for tonight, so please, please join me in thanking tonight's speakers for sharing their really interesting and ongoing research with us this evening.

Amanda Sciandra:
And we also like to give special thanks to those who made today's program possible. First of course, thank you to Busboys and Poets, our amazing restaurant collaborator. If you didn't place an order, a try one of the themed drink recipes this time, definitely added to the menu for next time. Thank you to our behind the scenes team who helps sort through your questions. To our donors, volunteers, all of you. And finally, to all of our partners who help us reach, educate and empower millions of people around the world today and every day. Thank you.

Naimah Muhammad:
Thank you. And mark your calendars for April 19th and May 17th. Those are the dates of our other Science Café events in this series. And we hope we'll see you there. We've also put a link in the Q&A where you can find more information about these and other upcoming programs. And where to sign up for the museum's weekly newsletter. It's the best way to stay informed on upcoming programs and learn more about the museum's research and upcoming exhibitions

Amanda Sciandra:
I'm of course biased, but that newsletter is great, and it's only once a week. And after this webinar ends, you'll see a survey pop up asking for some feedback. It's also in the Q&A. Please take a moment to respond. We really do read all of the responses and we're very curious to know what topics you might be interested in for future programs. And we truly appreciate your feedback.

Naimah Muhammad:
Thank you. And thank you to our participants. Thank you audience. And we will see you soon.

Amanda Sciandra:
Bye.

Naimah Muhammad:
Thanks everyone.