MAX WITYNSKI: OK. Welcome, everybody. I think we'll get started. What?
Good evening, everybody. Welcome to the Monday night seminar. I'm Max Witynski. I'm a senior in Biology and Society here at Cornell. And tonight it's truly an honor to introduce my research advisor Dr. David Bonter, who will be giving the seminar this evening.
Dr. Bonter, standing over there, he's currently the Arthur A. Allen Director of Citizen Science here at the Cornell Lab of Ornithology, a position in which he oversees programs like Project Feeder Watch, which is in its 30th season this year, and has over 20,000 participants reporting their sightings of backyard birds. Dr. Bonter got his PhD from the University of Vermont in 2003. And he's been affiliated with the Cornell Lab of Ornithology for the last 15 years.
During that time, he has not only been a leader in citizen science and outreach, but he's been extraordinarily committed to working with students. Dr. Bonter teaches the field course in bird banding here at Cornell. And he's also taught field courses in places as far away as Kenya and the Dominican Republic.
Dave was on the faculty of Shoals Marine Lab on Appledore Island, in Maine, from 2007 to 2016. At Shoals, Dave taught the Field Ornithology course and advised undergraduate interns studying the island's birds, primarily the herring gulls but other birds, as well. And you'll be hearing about all of that tonight.
Dave continues to work closely with undergrads here at Cornell who are interested in research. Last year he was recognized as a Professor of Merit in the College of Agriculture and Life Sciences, for his outstanding commitment to teaching. This is a designation that is significant because it is awarded by students, rather than by faculty or administrators.
It's been my privilege to work with Dave for the last four years on multiple projects, most significantly on my senior thesis, studying the migratory connectivity of yellow warblers, which you'll also be hearing about tonight. Dave is not only a phenomenal motivator and source of inspiration on campus, but he's also the epitome of a morning person. And so, it was his enthusiasm, not only on campus but also at 4:30 AM on mornings in the field in Maine, that resulted in the success of my project.
My story is just one of many that Dave will be telling tonight, as he talks about his research with students over the last seven years. And, since I'm sure we're all anxious to hear what he has to say, without further ado I'll turn the floor over to him.
DAVID BONTER: All right. Thank you, Max. It's a real pleasure to be here tonight, especially to have Max introduce me. I challenge anyone to find a better human being among the student body at Cornell than Max Witynski. I've known him since he was in high school. I met him at a conference when he was in high school. And it's hard to believe he's going to be graduating here in a couple of months.
It's also an honor to stand here in front of the Fuertes paintings. I distinctly remember coming down to the Lab of Ornithology for Monday night seminars, back when I was in junior high and high school, coming down from Rochester. And it was a different building, then. The paintings were in a different place.
But it's great to see that the Monday-night seminars continue. Apparently now there are a whole lot more people online than there are in the room. So I think I have to stand still and speak into the microphone, for the folks online.
So, thanks, everybody, for coming out. We're about to depart on a virtual trip to Appledore Island, which is one of the islands in the Isles of Shoals. This cluster of islands is located about an hour boat trip, on a boat like that one, research vessel like that one, out of Portsmouth, New Hampshire.
Being in the Shoals, even though it's an hour from the mainland, is like being in a completely different world. It's a land with a long history of riches and of squalor, of famous people and of famous murders. Maybe I can tell you about those later.
But science and conservation now reign in the Isles of Shoals. And I'd like to share a few of the stories from some of the students who I've been lucky enough to engage with on research projects out there, over the past decade.
And before we get to the islands, I'd first like everybody to think of a scientist. Imagine a scientist, in your mind's eye. Everybody have that image? You might be thinking of somebody like Carl Sagan or Mary Leakey. Stephen Hawking might come to mind, or the amazing and incomparable Jane Goodall. Pop-culture folks like Bill Nye or Neil deGrasse Tyson might come to mind or, if you dig even deeper back into the mental cobwebs, that crazy dude from Back to the Future, or some of the best Muppets that were ever made.
So now I'd like you to think about who does science, who engages in science. OK? You might be thinking of professors, PhDs, engineers, possibly lab technicians, maybe postdocs or grad students. But what about undergrads? This evening, I'll share with you some novel and exciting research in biology conducted by Cornell undergrads as they set the stage for their promising careers. And I'll hopefully convince you, along the way, about the potential of undergrads, particularly here at Cornell, to generate some quality scientific research.
And I'm incredibly lucky to work, here at the lab, with people like Anne Marie Johnson. And I've always felt lucky to work here. But what I didn't know when I came to the lab was how rewarding it would be, how exciting it would be to engage in genuine research with cohort after cohort of talented undergrads.
And tonight I'd like to take you on a journey of scientific discovery with some of these folks who I've been lucky enough to work with. This is a collection of current and past grad students. And I'm actually just noticing, the guy in the lower left, there, he just defended his PhD at UC Davis on Friday and called me up, all excited about that. So, a good group of folks.
Many of these students have worked out at the Isles of Shoals. The Isles comprises nine islands and a series of rocky ledges, again, off Portsmouth, New Hampshire. The Maine-New Hampshire state line runs right through the middle of the islands, so the northern islands are in Maine, the southern ones are in New Hampshire.
The islands themselves are a cluster of craggy rocks, with little vegetation other than poison ivy. Sounds great, doesn't it? It's a place where nobody is or would want to be, at this time of the year, although there might be a couple of snowy owls out there.
But the islands come alive in the summertime, thanks to the birds. Species like northern gannets are plunge-diving for fish in the cold waters of the Gulf of Maine. Wilson's storm petrels literally walk across the water as they're searching for little bits of floating food. I'd argue that there are few more inspirational sounds in nature than the sounds of eiders cooing and courting on a misty May morning. It's a wonderful sound.
The environment on the islands, it's alien, and it's exotic to most of us hominids. But it's the confluence of this really unique marine environment and the gobs and gobs of birds that come there in the summertime that really attracts the attention of researchers and students alike. And, as Max mentioned, I taught field ornithology at Shoals Marine Lab, which is located on Appledore Island, for the past 10 years. And that's an institution that's run by both Cornell and the University of New Hampshire.
On the islands, we try to leave the classroom behind as much as possible and get out and engage in experiential learning. And that learning often ends up leading to some publishable science.
Students are lucky. They get to engage in a lot of activities that most people aren't allowed to do in their normal lives. How many people have been to a tern colony? Just a couple? Max, you don't count! All right? Well, I'm going to take you there, this little bit of a video.
This is on Seavey Island, which is one of the southern islands in the Isles of Shoals. Not much more than rock and some grasses. But during the nesting season, about 1,200 to 1,500 pairs of common terns rest on this rock, along with a dozen or so roseate terns and a handful of Arctic terns, as well. And it's a pretty spectacular and sensory-overload kind of environment.
So that might have looked beautiful. That would have been landing on the island in June. But this is what it looks like if you actually go into the center of the colony.
It's, like, a Hitchcockian movie about the birds, there.
And you may have noticed that the students were wearing raincoats. It wasn't because it was raining.
But there was something a lot more viscous and smelly falling from the sky, there. And, as you can see, the vegetation on the islands is sparse, and few trees are larger than about 20 feet tall. As such, during the breeding season, the songbird community is pretty limited.
We have lots of yellow warblers, song sparrows, common yellowthroats, a few redwing blackbirds, a couple of grey catbirds, but not much else. But what's truly spectacular, in terms of songbirds on the island, is what we find during spring migration. And I have never experienced fallouts like you see on these islands in the Gulf of Maine during spring migration.
And if you're not familiar with migration, these songbirds are flying at night. Often, they're blown out over the open water. And, at first light, they have to find the nearest land, to settle down.
And islands, like the Isles of Shoals, attract just amazing numbers of birds, amazing diversities of birds, and even some birds that you really wouldn't expect. We banded painted buntings, three years in a row, on Appledore Island, Maine. It's about 700 miles north of the nearest breeding territory for them.
We've banded white-winged doves. Summer tanager are now becoming quite common. That's that speckled bird in the upper left, there. That's a young male summer tanager that isn't quite red yet.
I recall, one of my most vivid memories on the island was one really nasty, misty, late-May morning. And I was inside, lecturing and lecturing and just giving every lecture that I could possibly give, because the weather was so lousy. And finally, one student said to me, you know, Dave, I'm not I'm not tired of hearing you talk, I'm tired of hearing you talk inside.
So we went out, out into the miserable weather, and there were birds everywhere. Every bush had four or five species of warbler in it. We went down to the intertidal zone, and there were these mats of floating seaweed, on which blackpoll warblers, bay-breasted warblers, Blackburnian warblers were hopping around, eating the only insects that they could find, as those insects were coming out of the water.
One of my students sat down on a rock, and a Blackburnian warbler landed on his boot and just rested there for a while. So, just incredible experiences during migration, on the island-- if you're there on the right day.
And, as wonderful as the birds are, my most vivid and rewarding memories of my time at the Isles of Shoals have to do with this long lineage of inquisitive and dedicated ornithology interns. And there are too many stories to tell, but I'd like to share a few with you here this evening.
And, while not generally considered the cream of the crop in the bird world, the stars of the ornithological research show out in the Isles of Shoals are certainly the gulls. We have got the great black-backed gull, there, on the left. This is the largest gull in the world. They always look grumpy like that.
And on the right is the littler cousin, the herring gull. About 1,500 pairs or so of herring gulls nest out in the Isles of Shoals, and somewhere between 300 and 500 pairs of the great black-backed gulls.
These gulls come to the islands to avoid mammalian predators that could threaten their nests and eggs on the mainland. And fortunately, from our perspective, their nesting season coincides nicely with summer vacation here at the University. So students can go out to the island, start studying these birds, and see the entire reproductive stage happen during their summer on the island. It takes about 45 days for a herring-gull chick to go from hatching from the egg to flying.
We band as many of the birds as we can, to allow for individual identification. And we don't just use the metal bands, leg bands, that you might be familiar with. We also attach those field-readable bands, as well.
Those are made out of PVC, with three unique letters and numbers scribbled into each of those bands. So, just looking at the bird from 10 or 15 feet away, you can identify who that individual is without having to ever recapture that bird. With binoculars or a spotting scope, you can identify individuals from many, many yards away. And Julie Ellis, one of my great colleagues at Tufts University, has been banding the gulls out there for-- ooh-- I'm not going to say how long, because she'll be mad at me.
So these field-readable bands have allowed us to tap into observations from the public, citizen scientists all up and down the Atlantic seaboard who are seeing our birds and calling in and reporting those bands to us. And on the left of the screen, there, is Odile Maurelli. And Odile is a senior, working on her senior thesis here, right now. Absolutely horrified, by the way, that she's going to be graduating in a couple of months, because Cornell is so great.
But Odile has been taking blood samples from the birds that we band on Appledore and identifying, using genetic techniques to identify who's male and who's female. In the gulls, the males and the females look similar. And the only way we can definitively say who's a male and who's a female is by using genetic techniques. And just down the hall, here at the Lab of Ornithology, we have the Fuller Evolutionary Biology Lab, and that's where Odile has been running the analyses, there.
And basically what she's finding-- I'll let the cat out of the bag, here-- is that females are going a lot farther away from the nesting colony than the males. The males are homebodies. They rarely travel farther south than about Long Island. But we've had some of our female gulls showing up as far south as Brownsville, Texas.
And this scene may be a bit familiar to some of you, if you're a hardcore birder in the Ithaca area. This is taken at the Cornell compost piles, by our own Kevin McGowan, about 10 days ago. And if you focus on that large black-backed gull in the center of the photo, there, that bird has some bands on his legs. And that's actually a bird that we banded on Appledore Island last May. It's the second bird that we banded on Appledore that has shown up at the compost piles here at Cornell. And it's a little bit spooky that they're following me, but cool-- cool to see our birds showing up here.
And, although it takes a special birder like Kevin to really appreciate adult gulls, pretty much anybody will be taken in by the charm of gull chicks. They're adorable, they're cuddly, they're clumsy. My students claim that they're better than puppies or kittens, for at least the first two or three days of their life. After that, they enter an extended ugly, smelly teenage stage. But they're really cute when they first hatch.
And apparently they're also quite tasty. Gull chicks and eggs are the subject of a lot of predation on the islands. And although these birds nest out on the islands to avoid mammalian predators, and they nest in these dense colonies with other gulls, to drive out any predators that may come into the colony, those birds that they're collaborating with one minute to drive out predators can actually become the predators the next minute.
As we probably all know from McDonald's parking lots and then going to the beach, gulls are incredibly opportunistic. And any egg or chick that's left unguarded will be snapped up pretty quickly, like-- this is a great black-backed gull stealing one of its neighbor's eggs.
And, if you land on a gull nesting colony, you'll soon learn that these gulls are not passive bystanders around their nests. In fact, they can be quite vicious and vigorous defenders of their nests. And it makes sense, because they're investing a lot of energy in this reproductive effort. They only get one chance at breeding, each year. So, if something comes along and eats their eggs or chicks, it's a big deal.
And this is how they defend their nests.
[LOUD GULL CRY]
So they engage in this dive-bombing behavior. Often, they'll be defecating and splattering you with poo, vomiting on you. Just the noise. Sometimes they do make physical contact.
This is a very effective deterrent. And any of my students who've been out to Shoals, if they hear that "wah!" sound, they immediately just, like, cringe and duck. Yeah. So these are kelp gulls, but all gulls respond in the same way.
Which brings me to another student project that I'd like to detail a bit. I'd like you to meet Sarah MacLean. She graduated back in 2013. She was actually the SUNY Chancellor Award winner as the best student in all of the College of Ag and Life Sciences that year.
And I like to think that science is about asking and trying to answer questions. And I find that the best way to develop those questions is to actually get out in the field and start watching and seeing what's going on. Many of my students start out this way. They go out in the field, they make an observation, they ask a question, they dig into the scientific literature and develop the methodology required in order to collect the data to answer that question. And that's how it all begins.
Sarah came to Shoals the summer after her freshman year and was enamored by the gulls and the range of defensive behaviors that they displayed. And she was wondering how it is that they identify and respond to different threats around the nest. She was interested in digging into questions about gull cognition. What cues do they use to recognize potential threats?
Obviously, a predator walking up to the nest is a visual cue that the birds will react to. But are there other ways that they can identify potential dangerous scenarios and situations? Can they use auditory cues, noises made by the predator themselves, or possibly alarm calls from their neighbors of the same species or of different species?
And these defensive behaviors that you saw in that last video take a lot of energy. It doesn't make sense for birds to freak out and attack whenever there's any little disturbance in the colony. That's costly. But if they don't respond to a serious threat, then that's obviously dangerous, as well.
So Sarah was interested in whether or not gulls respond more vigorously to more serious threats. And, in order to get at this question, she designed what's known as a "playback experiment" to expose birds to a whole bunch of different stimuli and then record how they react. One of the stimuli that she offered up to the birds was the song of a song sparrow. This is a completely nonthreatening auditory cue. There are song sparrows nesting everywhere on the island-- absolutely not a threat to the birds.
Sarah was interested in neophobia, or fear of the new, and how the birds would respond to a novel sound that was nonthreatening but something that they'd never heard before. And so she played songs from the Western scrub jay to the gulls. This is a bird that would never be seen nor heard by gulls in the Gulf of Maine.
Sarah also played back alarm calls of both herring gulls and great black-backed gulls to herring gulls. And then she really upped the ante and played back the human voice. These were recordings of other students reading a passage from Jonathan Livingston Seagull. She thought that was funny. As well as vocalizations of bald eagles.
And humans have been historically and remain the biggest threat to gulls in the Gulf of Maine. They're still widely shot and discouraged from nesting. So nests are destroyed on a regular basis by people who don't want them nesting near their homes.
And bald eagles, since the DDT era, back in the 1960s, have made a truly remarkable recovery, which most of us are happy about. But if you're a seabird, you're not so happy about it. Bald eagles are becoming quite a problem in seabird nesting colonies on both the Atlantic and the Pacific coast.
So Sarah played back all of those different sounds to the birds. And she recorded the reaction of the birds, which engage in a set of very stereotypical behavior. So a gull can just continue to sit on the nest and incubate and not pay any attention. If they're a little bit interested, they'll stretch their neck up and look around and scan for what's making that sound.
Stepping up the ladder, they'll get up off the nest and walk around. They may even give these little "kek, kek," these mild alarm calls. And if they're really irritated, they start to fly around, looking for the potential threat. And then sort of the nuclear option is when they do that diving-and-pooping thing.
And what Sarah found was that the intensity of the response by the herring gulls was indeed related to the severity of the threat. So, on the graph, here, you can see on the vertical axis how intense the response was. 0 means they couldn't care less. 7 is that nuclear option. Along the horizontal axis, we have the different cues to which the birds were exposed.
So song-sparrow song, as we expected, had little reaction in the gulls-- cause a little reaction. Western scrub jay-- this is that novel sound-- piqued their interest, but they didn't bother to get up off the nest. When we started to play back alarm calls, that got the birds a little excited. They got up off the nest, started to look around, tried to set eyes on the potential threat.
The bald-eagle call was sort of right in that alarm-call range. We were a little surprised by that. We anticipated that would elicit a stronger response. But, in hindsight, that makes a lot of sense, because when a bald eagle is attacking, it's not vocalizing. So we think there was a mismatch between hearing the sound of the bald eagle and interpreting that as a threat.
But what really got them riled up was the human voice. These birds did not like hearing a human and not being able to see where that person was. And then, of course, the person walking up to the nest to set up the speakers and retrieve the speakers elicited the strongest response.
So Sarah's work led to three scientific papers that got her into a PhD program at UC Berkeley, in Conservation Biology. And she's working on that now and will hopefully be Dr. MacLean very soon.
And after spending a couple of summers really getting to know gulls and their alarm calls on the island, Sarah noticed that the vocalizations seemed to be more nuanced than people and researchers had previously recognized. We have one word to describe the alarm call of a gull. It's the "YEOW" call. And you'll hear that in a minute. To us, a YEOW is a YEOW. But Sarah's wondering if that alarm call is actually something more, if there's something more-- more information in there.
And that's where this delightful young woman Shailee Shah picks up the story. The big picture of what Shailee was interested in is how birds use vocal communication to convey a variety of information and signals to one another.
So we know that a songbird could sing. A male songbird may be singing, and he might be saying, hey, baby! You know, I'm over here. Come check me out. Or he may be saying, hey, dude, this is my territory. You stay out. So he's conveying both of those bits of information in his song.
A lot of birds give contact calls, to help maintain flock cohesion. At a certain age, they can give begging calls, to elicit a feeding response from their parents. And all birds out there give alarm calls of one sort or another, warning others to look out for danger.
And there's been plenty of research in recent years that shows that, contained within those alarm calls, those birds aren't just saying "danger" or "watch out." They're saying "danger-- hawk" or "danger-- snake." And the other individuals in the flock understand that and respond in an inappropriate manner.
In fact, the chickadee call, the "chick-a-dee-dee-dee-dee-dee," that's actually an alarm call. And we know that the more "dees" on the end of that "chick-a-dee-dee-dee-dee-dee" means that that bird is really-- the more "dees," the more upset that bird is, and the more dangerous the situation is.
So these birds are encoding information in their calls. Which brings me back to the herring gull. This is what the YEOW call of a herring gull sounds like.
[LOUD GULL CALL]
[LOUD GULL CALL]
[LOUD GULL CALL]
[LOUD GULL CALL]
[LOUD GULL CALL]
So you could hear the higher-pitched YEOW of the herring gull in the background. You might have heard some more lower-pitched YEOW calls. Those were from great black-backed gulls. It's essentially the same call, just different-sized birds produce that different pitch.
And Shailee's first question was whether or not gulls change their YEOW call depending upon the level of the threat. And, to test this question, she recorded calls of a nesting herring gull as a person walked towards the nest, starting about 15 meters away, where they would just start to say YEOW, until the person got right up next to the nest. She did this for a lot of different nests, analyzed all those sounds, using a program called Raven, which is sound-analysis software developed here at the lab, to test for differences between the calls.
So, Raven transforms that sound into a visual representation, like you can see on the screen, here. And those two sounds were produced by the same individual gull. The graph on the left shows the call, the YEOW call, when a person was pretty far away from the nest. The graph on the right shows the call when the person is right up to the nest. The horizontal axis is time, the vertical axis is the frequency of the call.
So I'm guessing that most people, just looking at those two graphs, not knowing anything about how this sound analysis works, you can probably look at those and think, OK, they're different. Right? They look different. But do they sound different? So let's take a look, starting with the low threat level, that graph on the left--
[RECORDED BIRD CALL]
--and high threat.
[RECORDED BIRD CALL WITH ARC TO HIGHER NOTE]
Back and forth.
[RECORDED BIRD CALL]
[RECORDED BIRD CALL WITH ARC TO HIGHER NOTE]
[RECORDED BIRD CALL]
[RECORDED BIRD CALL WITH ARC TO HIGHER NOTE]
[RECORDED BIRD CALL WITH ARC TO HIGHER NOTE]
You hear the difference? Yeah. There's a difference, there. So first Shailee found that the rate of calling increased, as the level of threat increased. As the person got closer, the birds made more YEOW calls in a shorter amount of time. And the calls themselves changed in structure and in pitch and had that little break in the middle, under the high-threat scenario.
So the next question is, so, yeah, they're creating these different YEOW calls, but do their neighbors, do their mates, do other individuals of the same species understand what these different calls mean? And, in order to answer that question, Shailee developed another playback experiment where she put a speaker out by a nest, this time put up a video camera to record what the birds were doing.
She set up a series of playbacks, one that was that high-threat-level call at a really rapid rate, high-threat-level call at a sort of relaxed, slow rate, low-threat-level call, rapid rate, low-threat-level call at a slow rate, and then the song sparrow again, as the control. And she recorded how the birds responded, just as Sarah MacLean did in the previous study.
So, again, the gulls responded with mild or almost no interest to the song-sparrow call. Low-threat-level calls instigated a greater response. The birds often were perked up and looking around for predators. Some of them would get up off the nest, stand by the nest, and look around. The timing didn't seem to matter too much.
But the high-threat calls played in quick succession really got the birds riled up, causing them to get up off the nest. They often took flight and started circling around, looking for something or someone to attack.
So Shailee clearly demonstrated that herring gulls encode the level of threat in their alarm calls, that both call type and call rate can be information about the urgency of the threat, and that the strength of the response to those alarm calls depends upon the level of urgency encoded in that message. And Shailee published this work in Animal Behavior, which is a scientific journal, the top journal in the field of animal behavior. And she is now working on a PhD at Columbia.
Yesterday, she was texting me, from East Africa, photos of rhinos and elephants and kori bustards. And she's about to begin six months of research on superb starlings in Kenya. So, look forward to see where she ends up in the future.
OK, As I mentioned earlier, spending time in the field is an excellent way to develop research questions. By watching and observing, it's pretty impossible for us to not start asking questions. And this next study results from an unexpected and a rather horrifying observation.
And my students told me-- right, Max? --that I need to give a warning, here. If unpleasant images upset you, look away, and I'll tell you when it's safe again. OK, I'm going to start playing this video.
This is a herring-gull nest. And if you're looking, you might see an egg and a chick and lots of little things crawling around. These are an invasive ant called "Myrmica rubra," the European fire ant. And this guy, Luke DeFisher--
--one of my interns on Appledore a few years ago, noticed that there were ants in a lot of these nests and started to wonder how the presence of the ants might be influencing the reproductive success of the gulls.
These are fire ants. If you've been to the beach in coastal Maine, they're a big problem, there, now. They were introduced back in the '70s. Now populations have grown quite large. If you're bitten by these, it burns. It's nasty.
So Luke spent the summer getting bitten by fire ants and monitoring a whole bunch of gull nests. There's the culprit, right there, on the beak of that chick. Myrmica rubra. So Luke followed about 100 gull nests throughout the entire nesting season. He recorded their hatching rates, the chick survival rates, their growth rates, and whether or not ants were detected in the nest.
And Luke clearly documented that ants can kill newly hatched chicks. In fact, they'll even crawl into eggs as they're hatching. So, as the chick makes a little hole in the egg, the ants crawl in and start attacking it and kill the chick before it even hatches.
The graph, there, shows differential growth rates between chicks being raised in nests with ants and chicks in nests without ants. So, quicker growth in the nests without ants.
But the good news is that these ants require soil. And the vast majority of gulls out in the Isles of Shoals nest out on the bare rocks. So, really, the only nests that were being affected were those birds that were nesting around the buildings and in the vegetation, which is a relatively small fraction of the birds.
So, Luke published this study, as well, graduated with honors, and he translated his interest in science to a career in the science of cider-making and distilling and now works for Apple Country Spirits, his family's business, and produces Rootstock cider, which is available down at Wegmans. I highly recommend it.
OK, so, a bit of a break after the somewhat depressing news about chicks being eaten alive by ants. This is just a gratuitous shot of a great black-backed gull chick. And some beautiful gull eggs.
Another observation that students often make, after even just spending five minutes in a gull colony, is that the eggs come in a stunning array of colors and spotting and sizes. And there's a lot of diversity, there. And all the eggs in this nest were laid by the same female.
Sort of the typical egg coloration is the egg on top-- that dark olive background, with the brown speckling. But the females can lay eggs that are more bluish and greenish, with varying amounts of speckling, as well. So you can see in that, nest, there, has very few dark spots.
And then occasionally we get some really, really strange eggs. And these birds, they're not the best at recognizing their own eggs. They will incubate anything.
That was not a plant. We found a tennis ball in a gull nest.
DAVID BONTER: It did not hatch, no. So, these observations led Michelle Moglia, here, on a tree branch with Shailee, to try to understand why there's so much variation in coloration in gull eggs. Are darker eggs better camouflage, perhaps? Does egg color indicate something about the quality of the female or of the pair? Is egg color related in any way to the survival of the egg or the chick that comes from that egg?
And the first step is to quantify, in a defensive and repeatable manner, the color of each egg. And egg colors, all egg colors on the planet, are determined by two different pigments. One's called "biliverdin," and that's responsible for the blues and the greens in eggshells. The other is called "protoporphyrin," and that's responsible for the darker colors, the browns. And it's just different proportions of those pigments in the eggs that determine all egg colors.
And so Michelle wanted to quantify that, and we used a device called a "spectrophotometer" to quantify the amount of light reflecting off of the egg shell surface across the entire color spectrum. And Michelle and I spent way too much time, one season, in this little pop-up tent, out in the nesting colony, just measuring the color of hundreds and hundreds of eggs. And then Michele followed the fate of each of those eggs throughout the nesting season.
And this is what the output from the spectrophotometer looks like. This graph shows the coloration of three different eggs from the same clutch. So these three eggs were laid by the same female.
The horizontal axis, there, shows the wavelength. So that's the entire color spectrum, on the x-axis. And the vertical axis shows the amount of light being reflected back at each of those wavelengths.
So there are three eggs here. The egg 1 and 2, those lines are essentially overlapping. So, to our eyes, those eggs look identical. We wouldn't be able to say, this is darker than that egg.
But that blue line, there, you can see, is quite a bit higher than the other two. That means there's a lot more light reflecting back in a big section of that color spectrum on that egg. So that egg's brighter. That would be a much bluer, lighter egg, to our eyes.
And we can see in that box. That's what our visual system allows us to see. Right? So, the red, blue, green, that that whole spectrum.
Birds have another cone in their vision systems. They can actually see down to the UV portion of the spectrum. So that's what birds see. Right? So there's an awful lot going on.
If you look down in that UV portion of the spectrum, from about 325 up to 400, that's an area that we can't even begin to perceive. But there's obviously a lot going on there. There's a lot of information there. So these eggs are looking very different to the birds than they're looking to us.
And ultimately-- well, I just wanted to highlight this box, here, too. So you can see, right there, that's in the blue-green range. And there's a big difference between those lines, there. So that top line shows an egg that's a lot bluer and greener.
And what Michelle found was that the third egg to be laid by a female was much more likely to be that bright, pale egg. Females were therefore investing fewer resources. Those pigments are costly to produce, and the females have a limited amount of those pigments to put into the eggs, and so they were investing fewer resources in those third eggs.
Chicks from third eggs were less likely to survive, overall. But chicks from pale third eggs and dark third eggs sort of had equal lousy survival probabilities.
So what Michelle thought was that these birds were essentially running out of ink. They have to produce three eggs in four or five days. They're putting a lot of energy into these eggs. And by the time that third egg comes along, the resources are depleted.
So Michelle spent two summers. And this-- I mean, Michelle is this 100-pound, little, petite girl, spending two summers in a colony of great black-backed gulls. I don't know how she survived it, but I think it prepared her well for a life as an investment banker on Wall Street--
--where she is right now, and hopefully making gobs of money. And she'll hopefully remember us, a few years from now.
And this is the last gull study, I promise. And this is an update. If you came to a Monday-night seminar last March, here at the Lab of Ornithology, you heard Taylor Heaton talk about her research. Taylor has now graduated and moved on.
But Taylor was really interested in parental defense behaviors and how these birds respond to threats to their chicks. And the first thing she did was to quantify when during the chick stage these guys were vulnerable. And the graph, there, shows the survival probability on the vertical axis, throughout the chick development stage.
So, from days 1 to 5 and 6 to 10, there's a lot of mortality happening. Only about one in five-- sorry, one in five chicks dies during those first five days of life. It's also bad during the second five days. So that red zone, there, that's the danger period.
And Taylor conducted behavioral experiments with the adults to determine how aggressive they were-- to measure their aggressivity, if that's a word-- to measure how aggressively they defended the nest at different stages of the chick's development. And she found that the parents are incredibly aggressive when the chicks are most vulnerable. So, during those first 10 days, the parents are violent defenders of their nests.
Once the chicks start walking around, reach their teenage years, the parents sort of lose interest, and the kids are on their own. The chicks can then go ahead and hide in rock crevices. But the parents are really defensive during those first few days.
And Taylor's manuscript was just published, last month, in a journal called Ethology, which is great news. OK. That's the end of the gulls. But before I wrap up, I wanted to highlight some work conducted by students who some would say were smart enough to not study gulls. And that's just a nice shot of the lighthouse out on the Isles of Shoals.
But this is Liam Berigan, who is a senior in my lab group, now. And I'm going to let Liam tell you about his project.
- Hi! I'm Liam Berigan. I'm Cornell class of 2017. I'm the gull intern on Appledore Island, for Shoals Marine Lab, the summer of 2016. And I'm doing eider surveys on the island.
So what I'm doing is I'm going around the islands, trying to find as many of the eider nests as possible. And when I find an eider nest, I make a GPS point there.And I'm recording how high the vegetation is, where the eider nest is, the type of vegetation, and how well the eider nest is concealed.
And the idea is that I can take this data later, put it into a computer, and try to determine what types of vegetation that the eiders like to nest on on the island.
DAVID BONTER: That was only the second take, so I was pretty proud of Liam on that one. Eiders are really intriguing birds. They're beautiful birds, but they're really hard to study.
They nest in briars and poison-ivy patches. Here are photos of two nests. Really large eggs. The nest themselves are made out of eider down that the female plucks from her breast.
Males are complete deadbeats. They have nothing to do with the reproductive effort. And, once the ducklings hatch, the females take them right to the water, where they begin feeding on their own.
They're incredibly precocial. So they're walking and swimming and feeding on their own, right from the beginning. They just need the parents to defend them.
But in the Isles of Shoals it appears as though most of those eider ducklings are ending up in the stomachs of gulls. But we don't quite understand what's going on, because it seems as though the eider populations are stable or increasing, even though reproduction is almost nil. So it's something that would be great to study more, but they're very difficult to study.
Here's another short video clip from Liam, showing the really large eggs that these ducklings come from.
- What do you have there, Liam?
- This is an eider egg, which is starting [INAUDIBLE]. I kind of see the bill coming through now, as it forces its way out with its egg tooth.
DAVID BONTER: And if you're observant, you can see that Liam's hand is right on a clump of poison ivy. He spent the entire summer finding eider nests and going through these briars and poison-ivy patches and survived. Which is miraculous.
And what he found was, just on one small section of the southwest corner of the island, Liam found 204 eider nests. And, to give you an idea of the size of this, this area, the footprint of this area is roughly the size of the footprint of the Lab of Ornithology. So, if we just walked around the first floor of the lab right now, imagine finding 204 eider nests in that area.
And these things are pretty hard to find, so chances are there are were few more in there that he couldn't find. So all those red dots, there, represent eider nests that Liam found in that poison-ivy, briar tangle this summer. And there's some interesting clustering, there. A lot of these birds nest really close to one another. Sometimes the nests are even touching each other.
We've also spent some time studying a rather unique population of barn swallows that nest out in the Isles of Shoals. It's unique because the nesting phonology in the Gulf of Maine is quite delayed. The water around the islands never gets warmer than about 53 or 54 degrees.
That means that leaf-out on the vegetation is much later than on the mainland. The insects arrive later than on the mainland. There's less food for the barn swallows. So our barn swallows on Appledore Island start nesting at about the time that birds on the mainland, 10 miles away, are fledging their first clutch. So our birds rarely are able to get two clutches of chicks out, per year.
And this is Collin Hertz, who graduated back in 2015. Collin was really interested in the provisioning behavior of birds. And that's how mom and dad bring food to the chicks. And, as we know, in most animals the females do most of the work. Right? Females do most of the work.
But what Collin was interested in is whether or not and to what degree the males were actually helping out in raising these chicks. The females do all the incubating. But, once the chicks hatch, the males do visit the nest and bring food.
The problem is, it's really hard to study provisioning behavior. Imagine sitting in a blind, in a dark crevice underneath a building, trying to watch a nest, hour after hour, and see who comes in and who's bringing food and so forth. So we ended up using a technological solution.
There's an antenna around the top of that nest, there, which recorded radio-frequency identification tags, or PIT tags. So we put PIT tags, these little transmitters, on the male and the female and then had the antenna on the nest. So, every time a parent came to the nest to feed the offspring, we knew who it was and what the time was. All right. So, do you think dads pull their weight?
DAVID BONTER: No? They try. They try.
So the male barn swallows are providing a lot of food to the chicks-- not quite as much as the females. The females are the open circles, there, the marks on top. The males are coming quite a bit, but just not quite as much as the females.
And we did notice a lot of variation among the males. Some were pretty good dads, some were pretty lousy dads, some fed chicks in multiple nests. And if you know much about swallows, you know that they tend to be among the players of the bird world. And those males likely had paternity in multiple nests. And it's possible that they're feeding multiple nets because they had chicks in multiple nests. We don't have the blood samples to actually prove that, but I think it's a pretty good hypothesis of what's going on and provides an interesting question for some future research out there.
And if anybody has ever worked with swallows, or had them nesting around their home, you probably know that, as far as birds go, swallows are pretty filthy. They deal with a lot of ectoparasites-- lice and fleas and mites. And it's these mites that can be particularly problematic in swallow nests. We've even documented several instances of chicks in nests that are just full of mites, just leaping out before they're ready to fledge, essentially committing suicide because they're being swarmed by these parasites.
And so this is Facundo Fernandez Duque, who may or may not graduate. Tell him I said that. So, Facundo spent a summer out on the island two years ago, looking at how mites influence reproduction in barn swallows.
And he found that barn swallows being raised in nests with lots of mites had much slower growth rates than barn swallows in mite-free nests. So, age, again, along the horizontal axis, the weight of the birds along the vertical axis. And at the end of 13 days-- these birds fledge around 15 days old. But after 13 days, there's about a 10% difference, on average, in weight between birds in mite nests versus nests with few mites.
That's big. 10% difference is huge. We know from a lot of research in birds that the weight of a chick at fledging has cascading consequences for the survival of that chick in the post fledging period and its ultimate success throughout its life.
The photo, there, is a pretty scary photo, showing two barn-swallow chicks from different nests. Those chicks are the same age. The upper chick was from a nest with lots of mites. The lower chick is from a nest with no mites. So, you can really see, there, how high ectoparasite loads can influence reproduction.
And so, although studying lice and mites isn't the sexiest of projects out there, there's a lot to learn. And Facundo's work highlights the research need there.
And finally, before I wrap up, I'd like to share some research news that's just now breaking. This is the first public audience to get these results. And these results are from Max Witynski.
Max studied yellow warblers in Maine and in Wisconsin. He put those little devices on their backs. It's called a "geolocator." They wear it like a backpack. And that device records where the bird is.
We put these transmitters on birds on the breeding grounds. They wear that for the entire year. They go down to a wintering location-- come back. The goal is to catch the bird again, take that device off, download the data, and find out where they've been.
And here's a little preview. This is a young Max Witynski, summer-- this is probably, what, May of 2015, talking about his work.
- All right. I'm Max Witynski. I've been attaching geolocators to yellow warblers, here on Appledore Island. They're like this. The light stalk records ambient light levels over the course of the year. And [INAUDIBLE] bird next year, we can use that data to figure out where he spent the winter. So, it's pretty exciting.
DAVID BONTER: And we did recover that bird and six others that wore the backpacks for the entire year. And we were able to see where they went. And Max is going to come back up right now and do the big reveal of where yellow warblers spend the winter. OK? And I will--
MAX WITYNSKI: I guess, before I change the slide, is anyone familiar with the winter range of the yellow warbler and have a guess where the birds from Maine versus the birds from Wisconsin that we tagged spent the winter?
MAX WITYNSKI: Pretty close.
DAVID BONTER: Good!
MAX WITYNSKI: [LAUGH]
DAVID BONTER: Any other guesses?
MAX WITYNSKI: Awesome. In between those two locations. So, this is a map. So we had two breeding populations that we tagged birds from, one near my home, in Wisconsin, which is the blue dot, and one on Appledore Island, in Maine, which is the red dot up in the United States.
And so, we recovered four birds from Maine and three birds from Wisconsin. And the most interesting takeaway, I think, from this map is that you can see that the birds from Wisconsin actually spent the winter in Venezuela, east of the birds from Maine, which wintered mostly in Colombia. So the longitudinal segregation on the wintering grounds doesn't match that on the breeding grounds, which is pretty interesting. And it shows just how much we have to learn about where songbirds from our backyards spend the winter and whether or not that correlates to where they spend the summer.
So, all of those migration paths are more than 3,000 miles long. Unfortunately we only have the data for fall migration, because the battery life of the device is only nine months. But it's still really interesting and really exciting. So, I'm working on putting that thesis together now. Thank you guys.
DAVID BONTER: He'd better be working on that thesis now. All right. So that was the world premiere of yellow-warbler migratory connectivity. Thanks, Max.
So those are just a few of the stories of the impressive research that the undergrads can accomplish when they're sort of set free to explore, to ask questions, and to study in a pretty remarkable place like the Isles of Shoals. To conclude, I'd like to allow each of you to sort of experience what it's like to be an intern at the Isles of Shoals. This is a film that was directed and edited and put together by Sarah MacLean, who you met at the beginning of the talk. And this is called A Day in the Life. I did not pick the music.
DAVID BONTER: This was my editing mistake, right here.
This was not part of Sarah's original movie. But I like M35. He's a nice gull.
DAVID BONTER: These are the southernmost-nesting black guillemots on the planet.
Grey catbird. Black-billed cuckoo.
- [INAUDIBLE]. It's just so adorable.
- [INAUDIBLE] little wing?
- I know! [INAUDIBLE]
- [INAUDIBLE] behavior.
- Hello! We could use some masking tape [INAUDIBLE] you see the whole setup in here? We have chairs, now.
- [INAUDIBLE] not the right way to carry [INAUDIBLE].
DAVID BONTER: Shailee, with her sound-recording equipment.
- And there's a huge spike in ultraviolet light, which we can't see but the birds can see. So it might have some different or really cool effect on the way birds see this egg, and maybe on how this egg survives [INAUDIBLE]. It's just really exciting, because it is so rare!
Ah! Oh my gosh! [INAUDIBLE]. It's so cool! I'm going to freak out. It's just so cool.
- [INAUDIBLE] Nope, nope! [LAUGH]
- Yeah, he did that when he was out of the water, and I dropped him. But I got him back. [LAUGH] [INAUDIBLE]
DAVID BONTER: All right. So I'd just like to end by thanking a whole lot of folks. The Redhead Fund for Undergraduate Research here at the lab has really helped support a lot of this. Jean and Betty, thank you. They're embarrassed, back there, but thank you for your support.
Lots of different programs at Cornell that support undergrad research. I'm incredibly envious of the opportunities that these students have. And then a lot of my colleagues who help out at the Isles of Shoals. So, thanks to them, and most of all, thanks to the students who have made me want to get up and out in the field at 4 o'clock every morning.
I'd be happy to answer any questions. Yeah! Go ahead.
AUDIENCE: What kind of recovery rate do you have on the geolocators? How many did you get back?
DAVID BONTER: So I think I have to repeat the question, for the people on the web. "Repeat question" sign. Thank you, Mary.
So the question is, what sort of recovery rate did we have for the yellow warblers that were wearing the geolocators? We put out 20 and got back 7 of the devices. Which is-- in a normal year, you'd expect only about a 50% adult survival rate. So, best-case scenario, we would have thought we'd get 10 back, and we got 7 back. So that was pretty good.
There are rules about how much weight you can put on a bird. You can only put on less than 5% of the bird's body weight. And these devices are so small and so light, now, that they weigh less than 5% of a yellow warbler, which is about-- so they weigh about 0.4--?
MAX WITYNSKI: A little less than that.
DAVID BONTER: A little less 0.4 grams, those little geolocators. Jean.
AUDIENCE: To what extent do the students-- the interns, the other graduates-- try to replicate studies that other have done, compared with original research?
DAVID BONTER: All of my students have done original research. And the reason is, it's becoming increasingly difficult to get replicated studies published. If it's not new, and it's not novel, journals don't care. So these students--
You know, it's changed so much since I was in grad school-- oh, Jean, I was supposed to repeat the question. [LAUGH] The question is, how many of these studies are replicated studies, and how many are new and original research? And they're pretty much all new.
When I was in grad school, or when I was applying for grad school, you could just send in an application, like you do for undergrad, and get accepted. These days, so many students want to stay and get advanced degrees, it's really hard to get into grad school. And so the students are highly motivated to get publications, to get peer-reviewed scientific publications out from undergrad.
It wasn't even on my radar when I was a student, when I was an undergrad student. But these kids, now, are putting out-- you know, some of them are putting out two, three papers from undergrad, which is a ticket into grad school. So they really want to do original research that allows them to get into grad school.
I think we have a question from the web.
SPEAKER: --couple questions from the lab chat.
DAVID BONTER: It better not be my mom.
SPEAKER: So, the first one is if you have a guess of the percentage, how many students go into a related field, versus something pretty different?
DAVID BONTER: Oh, that's a good-- yeah, good question. I can only-- of the students I've worked really closely with who've done senior theses with me, only two of them went sort of outside of the biology realm. But I think that's a little unusual. What I tell all students now, get a Computer Programming degree, because people will be throwing money at you. So. Another question? [INAUDIBLE].
AUDIENCE: How much do those little geolocator backpacks cost?
DAVID BONTER: Ah, the question is, how much do those geolocators, those little transmitters on the yellow warblers, how much do they cost? They were in British pounds, so it depends on the exchange rate. But I believe it was something around $250 each. So. Yeah. To get electronics that small, it costs. Yeah. Yeah!
How did the fire ants reach the island from the mainland?
The question is how the fire ants, those invasive ants that are attacking the gull chicks, how they reached the island. Actually, those ants, they're European in origin. And so shipping brought them to coastal New England. They're now all up and down the coast.
They haven't moved inland very far, but a lot of beaches have problems with people being bitten by ants, as they're laying out in the sun. So, I don't know that we actually know how they originally came to North America. But it was people. People did it.
AUDIENCE: How'd they reach the islands?
DAVID BONTER: Oh, there are boats going out there every day. There are logs floating up on shore. Muskrats swim from the mainland. So it's not that far. It's--
DAVID BONTER: There are muskrats out there, and people have put raccoons out there, in the past, to get rid of the gulls, which was not a good thing. But, yeah, it's not that far from the mainland, but it often feels like a completely different world. When the fog rolls in, and you can't see the mainland, and it's, yeah, it's like you're in a-- it's a surreal experience, out there.
[INAUDIBLE], you had another question from online?
SPEAKER: Someone had asked if anyone has looked at bonded parental pairings on the island, to see if there's any greater success.
DAVID BONTER: So, yeah. So these birds can live to be quite old. And if both the male and the female is alive, more often than not they stick together and will mate together, often on the same scrape on the ground, year after year after year. So we have a number of gulls that we know, known pairs, that are really-- they're island heroes.
There's the Herringtons, a pair of herring gulls which--
--the students love, every year. So, sort of these birds that are in known locations. What we do know about the success of pairing is we know that young males are stupid and not good parents. So if a female pairs with a young male who-- it's his first reproductive attempt, it almost always fails. They have to try a couple of times before they figure it out.
The issue is that we have a female-biased adult population. There are a lot more females out there than males. We don't know why yet. It's something we've been trying to figure out.
So there are a lot of desperate females who are willing to mate with anything. They have mated with other species. And they'll often mate with immature males.
So these are males that are kind of hanging out on the island, they're not serious about reproducing, but, you know, the females try it anyway. And it almost always fails. So I would guess that the pairs that are together for long periods of time end up being quite successful. If they fail a couple of years in a row, we also know that there's divorce. So, if they try with one mate a couple of times, it doesn't work, they'll split up and find somebody else. Betty?
BETTY: Regarding the eggs [INAUDIBLE], a few years ago, three years ago, I was out on Shoals, and we were doing a count of gulls. But they had green tags. And I notice these tags are a different color.
DAVID BONTER: Yeah, we put green tags on the herring gulls and black on the black-backed gulls. And it's a coordinated system, all up and down the Atlantic seaboard. One of my collaborators and grad-school buddies, Noah Perlut, is studying gulls in Portland, Maine. And I think he uses orange tags.
So the color helps identify the nesting colony. And yeah, you only have three digits, so we use colors and combinations of digits to make everything unique. Yep.
AUDIENCE: How many students actually participate in this program? And, [INAUDIBLE] of which, how many of them actually write a senior's thesis or publish something?
DAVID BONTER: The question is, how many students participate in this program? And how many of those write a senior thesis? How many are in the lab group now, Max? It's like, 20? Yeah, I've got about 20 students in my lab group right now.
For the last 10 years, I've had two or three interns on the island per year. Pretty much all of them do senior theses, because that's sort of the goal. So, yeah.
AUDIENCE: Do you know anything about the nesting-site fidelity of, say, for example, the barn swallows that you find out [INAUDIBLE] on the island? You said that the gulls come back to the same scrape. Do the passerines do the same thing?
DAVID BONTER: Yeah. The question is about nesting-site fidelity in birds other than gulls on the islands. And, yeah, all of these birds are remarkably faithful to their breeding areas. In fact, the yellow warbler-- we only put the transmitters on male yellow warblers. And I knew where we caught them last year. And so I'd go out there and find those males singing in the exact same bush where we caught them last year.
You know, they're either going to Venezuela, they're going to Colombia, and they're coming back to the exact same spot. The barn swallows will reuse nests, year after year, which can be a problem, because that's when the mite loads build up.
But it's sort of a balance, right? If you build a new nest, it takes a lot of time and energy, and it delays your reproduction. So that's bad.
But a new nest doesn't have mites. You can reuse an old nest that has mites. It's a trade-off. But all these birds have a remarkable level of fidelity to their nesting areas. Yeah. All right. One more.
AUDIENCE: Do those ants possibly have that kind of insecticide quality that other ants have, for [INAUDIBLE] birds that rub themselves around the ant nest--
DAVID BONTER: Yeah--
DAVID BONTER: The question is whether or not the birds on the island use the ants in what's known as "anting" to keep parasites and such off their feathers. I've actually not seen that on Appledore. Having been bitten by the fire ants many times, I would not recommend that to the birds.
One thing we do see on the island is, we think it's because, and the ant people will tell you it's because, these are introduced ants, and they form super colonies in the introduced areas. So, huge, huge numbers, much higher than they would be back in their native Europe.
Because they're so genetically similar to one another, the different colonies don't recognize the neighbors as sort of the enemies. And typically, ant colonies sort of keep each other in check. They're battling over territory.
But on Appledore, all of these ants are genetically essentially identical, because they're introduced. And it's this one, huge super colony. So we get incredible numbers ants out there. It's, uh, yeah. It's not fun. Good!
All right! Well, thank you, everybody, for coming out.
Thank you, Max!
AUDIENCE: Hi, so, thank you for the lecture. I'm from the [INAUDIBLE]. And I was just recording your lecture, because I want to cover it in--
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The Isles of Shoals, a craggy archipelago in the Gulf of Maine, is an ideal place to immerse students in learning and research focused on birds. For the past decade, Dr. David Bonter has taught Field Ornithology and mentored research of Cornell undergraduate students studying the eiders, swallows, gulls and warblers that invade the islands during the breeding season.
This presentation, given Feb. 6, 2017 as part of the Lab of Ornithology's Monday Night Seminar series, will virtually transport you to Appledore Island where you’ll learn about the students’ findings and experience their journey through the trials and tribulations of ornithological field work.