Joshua Brumberg:
Good evening. I am Josh Brumberg, the Interim President here at the Graduate
Center. It's my great pleasure to welcome you here tonight for our Spring City of Science Event
Birds, A Day in the Life. As a public university, the Graduate Center, and its associated Advanced
Science Research Center are committed to the idea that our scholarship has a role in advancing the
public good. Before touching on tonight's event, as many of you know, we are a national leader in
graduate
education at the master's and especially the doctoral levels. We are the home of innovative
research and creative works of Nobel, Guggenheim, and Pulitzer Prize winners. We are one of the
largest PhD-granting institutions in the country, and we are especially proud to rank among
the country's top 10 institutions in awarding doctorates to students from under-represented
groups. I am confident in saying that no other graduate school in the country takes more
seriously its public responsibilit
ies or its mission to advance knowledge for the public good.
We are not only a place dedicated to advanced education and research, it is also a laboratory
of idea, which delivers the finest research and scholarship to and far beyond the five boroughs.
Each year our doctoral students teach more than 130,000 undergraduates at the City University
of New York, bringing the very best research and learning from the seminar room into the classroom.
I hope that you'll make a habit of attending our p
ublic programs, lectures, and events so you can
truly be part of the city of science. Now it's my distinct pleasure to introduce tonight's
panelists. First, to my far left is Professor Orie Shafer, who is a member of the Neuroscience
Initiative at the Advanced Science Research Center and a member of our Biology Ph.D. program and a
chronobiologist, and you'll learn what that is by the end of the night, whose research utilizes
the fruit fly to study circadian rhythms. And I'm joined in the mi
ddle by Dr. Mark
Hauber, who is the executive director of the Advanced Science Research Center and an
expert on parasitology in birds and the author of the recently released Bird Day, which we are
celebrating tonight. Before we start, a few ground rules, I'll be leading our panel and discussion
for the first part of tonight's program. And then towards the end, I will open it up to questions
from you, the audience. And please, when you do ask a question, wait until you're holding the
microp
hone and speak into the microphone so our audience on Zoom can hear your questions as
well. All right, starting it off. All right, Mark, what made you decide to write a book?
Mark Hauber: That's a great question. I wrote a book about 10
years ago called the Book of Eggs, and it was a crazy experience. I spent six months at my really
pretty table that was made out of pieces of the Brooklyn Bridge writing 14, no, 140,000 words.
And so 10 years later you sort of have the bug in you and say like
, "Oh, I should write another
book." And this time I wrote a little book, but it was the idea that I really wanted to write
about what do birds do all day long? And the same press, University of Chicago Press, was willing to
take a bet on it. And so today there's a book. Joshua Brumberg:
Do you have an estimate about how many birds there are in the world?
Mark Hauber: 10,000.
Joshua Brumberg: 10,000. And so how did you choose the
24 that are included in this book? Mark Hauber:
So I chose bir
ds that I care about. I chose birds that I wanted
to learn more about, and I chose birds that my friends studied. So I wanted to make sure that
the book is based on primary research, articles, peer-reviewed articles that people have published
on them or things that I could read, but it also includes birds that I really wanted to highlight.
So my study species, American robin, brown-headed cowbird, common cuckoo, are in the book. And then
my friends' study species, like the Cook's petrel or
the kakapo are also in the book.
Joshua Brumberg: All right, and I think we're going to show
a few pictures if we could get the slides. And I know these are some of your favorite
birds. So we're going to walk through these, and tell us what made you choose them and why
they do what they do during what time of day. Mark Hauber:
Very good. So the barn owl is a wonderful species because it occurs on
most continents. The one that it doesn't really occur on has about 12 different species of barn
owl-looking things, Australia. And so it's also a great study system for neuro-ethologists. So
barn owls have a hearing system that's really well studied. I once met somebody who said, "I
did my Ph.D. on one and a half owl," and I didn't want to know what the half owl meant, but I know
he was a neuro-physiologist and he was studying that bird for a while. But barn owls are not only
charismatic, they're also commensals of humans. They live in buildings, they live in towers, they
live in aba
ndoned attics, and they come in two different color morphs. So whether it's color,
whether it's behavior, whether it's hearing, whether it's the nocturnal behaviors, they really
represent something that's worth writing about. Joshua Brumberg:
And these birds would probably start being active about right now, searching for
their food. How does it know the time of day? Mark Hauber:
Orie, do you want to take a guess at that? Orie Shafer:
You want me to take that? Mark Hauber:
Sure. Orie Shafer:
Well, as it turns out, every animal on the planet has a clock in its brain, a very small
region of the brain that is an exquisitely timed, highly accurate clock. And so it's hard to imagine
why an animal would need this. We essentially live on a clock. It rotates once a day instead of
twice a day like ours. But as it turns out, animals display really striking behavioral
changes, physiological changes throughout the day, and that does not require any information from the
environment. There i
s an extremely well-designed clock in the brain that will tell this owl it's
time to go hunting, whether it knows what time it is outside or not.
Joshua Brumberg: All right. And I think we have the next bird.
Mark Hauber: Very good. So when I was in Germany during COVID,
I was living at Urbana-Champaign in Illinois, which if you've been, it's not like New York City,
it's really boring. And so I got some fellowships to move to Germany. And instead of taking the
best one, I sort of took them i
n sequence. So I ended up living in Germany for two years, and
one time it was January and it was like 7:00 in the morning, pitch dark in Bremen. And there was a
European robin singing right over the streetlight that was still illuminated, because in Bremen at
7:00 in the morning in January, it's still dark. And so it really caught me because we know the
robins sing at night in urban places, we know nightingales do it on their own. And there's
a nightingale chapter actually in the book. But
this robin singing next to the light
was something that caught my attention. It was also freezing cold, and so you wonder if
your gonads are not developed, what makes you sing at that point of the year? And so we know
that birds, like starlings, actually generate testosterone in the brain rather than in their
testes, for instance. So we do have these winter singing birds, but this one was also singing
at night, which was an extra complication. Joshua Brumberg:
So that brings up another iss
ue. Orie already commented
that birds can tell the time of day, but also what you were just saying, they also
can tell the season, and that elicits some behavior. Some will fly south in the winter.
How do they sense the change in the season? Mark Hauber:
Go ahead. Orie Shafer:
Well, so getting back to those clocks within the brain, it isn't entirely clear,
as I said, why an animal should need a clock, given the fact that we live in an extremely
predictable rhythmic environment. The world it
self really presents a pretty good timepiece.
The original idea for why these clocks exist was not actually to explain daily rhythms and
behavior. The original hypothesis named after Erwin Bunning, called the Bunning Hypothesis,
was actually designed to explain seasonality, particularly in flowers, but it also counts for
photoperiodic animals. So an animal may hibernate in the winter and have to prepare for that.
And one of the main cues for when winter is coming is day length. If the days a
re getting shorter and
shorter and shorter and that animal can measure time, it can prepare for these radically different
seasons. And so the idea is in order to actually measure day length and keep track of day length,
one needs a clock. And so the original idea for why these clocks are adaptive in an evolutionary
sense was it gave the animal, the plant the ability to measure time, to measure day length
and reckon whether summer or winter is coming. Joshua Brumberg:
Now, both these birds,
Mark, you made the point, the owl is found on virtually every
continent but Australia. This is a European robin, but obviously we have robins here in America. Do
they behave similarly, whether to sensing time or their singing or their behaviors, or do the
Europeans act differently than the Americans, like people do?
Mark Hauber: They certainly do because the American
robin is not really a robin, it's a thrush, right? Turdus migratorius. So their closest
relatives are European blackbirds, so
ng thrush, the red wing, which is not to be confused with the
red wing blackbird. And so I had a job actually in New Zealand where Europeans introduced their
favorite species, because why should you look at native New Zealand birds when you can have
a European blackbird or a chaffinch, right, or hedgehogs if you're a mammal person? And so
we actually compared the breeding behaviors of blackbirds in Europe versus New Zealand, and they
have fewer eggs in New Zealand. It's well known that Sout
hern Hemisphere birds in general have
fewer eggs in the nest than Northern Hemisphere birds. But even an introduced species evolved
over 150 generations of living in New Zealand to have fewer eggs in the clutch. And so the
birds are actually doing different things. In New Zealand, nobody preys on the adult robins
or adult black birds, because the predators are gone extinct too. But there are rats, people
brought rats with them, and the rats eat the eggs. And so what happens is life history
wise,
the birds pay very little attention to every nest. They lay a few eggs, but what happens is they
live forever, and so they can lay another egg, another nest, and another nest and another
nest full of eggs. And so they change their life history, they change their investment into a
clutch of eggs based on whether that nest is going to be surviving or not. So depending where these
birds are, they're doing very different things. And introductions are sort of nature's perverse
experiments
, or humanity's perverse experiments, to be honest, to see what happens when you
translocate a species to another continent. Joshua Brumberg:
All right, and I think we have one more example.
Mark Hauber: Oh, yeah. So this is the cover of the book,
an original picture I can't afford because the wonderful illustrator, Tony Angell, is selling
it for so much. But if you have the funds, please buy it from him. I have the chapter
at home, it just arrived the other day. This is a classic image. I w
anted to write about the
secretary bird, which is an African hawk species, because it kicks snakes to death. And that
alone, it's a current biology paper by Steve Portugal and his collaborators, but that
alone is worth a chapter, if not a whole book, if not a whole New York Times article.
And so we were actually able to afford to paint the eye ring of the secretary bird orange
on the cover of the book. And so if you see it, it actually comes in three colors. But this
bird also brings up som
e conservation concerns. So this is an African savanna species, and
it's getting so hot through global change, even in the savanna that the breeding success of
the birds is going down. The chicks are not able to make it. They are literally boiling to death.
They are dehydrated at the nest. And so even in some of the hottest habitats in the world,
global change is causing the birds to have depressed reproductive success. And so that's
the other angle that I cover in the book. Joshua Brumberg
:
So these three birds are active in different times of the day. Do you have any thoughts about why
this bird is active, I think it's a daytime bird, the owl is much more of an evening bird? It's like
a chicken or egg problem. Forgive the pun. Why does a bird go into that niche in the day?
Mark Hauber: Yeah, so with the secretary bird, they are
snake specialists, and so the snakes are out in the middle of the day when heat is there, they
are poikilothermic, so they need the heat to be able t
o move around. And so the bird is active
during that part of the day. In fact, it was actually kind of hard to find species that did
something interesting in the middle of the day, because if you're a birder, you go out at 5:00
AM, and there's morning chorus or dawn chorus, you go out at night and all the dusk birds are
coming out. And then you're out there at 10:00 and really nothing is happening. And so some
people who actually read through the book, they were like, "Well, why is Mark tal
king about the
duck sleeping in the middle of the day?" Because that's what they do. They sort of take a nap and
then they become active again in the afternoon. Now, the robin is sort of the outlier in the
sense that it's a daytime bird, except it also sings into the night when there's artificial
illumination. And then the owl is a mammalian predator, right? And most mammals, most rodents
are nocturnal, which makes them not so great as a model for studying human behavior, because we
are di
urnal. At the same time they're mammals, so their genome is more similar to ours.
And that's my biomedical argument for why we study birds. But if you're a mammalian
predator, you need to be active at night. Joshua Brumberg:
When birds are active at the different time of day, you said the duck was
sleeping during the day, I would like to take a nap during the day, do all the birds take naps or
do some just active, active then go to sleep? And what determines that?
Mark Hauber: Again, if you'
re a birder, you know a lot
of birds are just taking it easy. Maybe the insects are not as active or other predators
are out there. These ducks are a good example, because they are still being preyed on in the
middle of the day. So they go to sleep with half of their brain. One of their eyelids is open, the
other one is closed, and so half of their brain is asleep while the other one is looking out for
predators or bumping into neighbors or looking at potential mates and things like that. B
irds have
this wonderful laterality in their eye use. So they literally use one of their eyes to look for
predators and they use their other eyes for sex, which on Valentine's Day is a fair thing to do.
Joshua Brumberg: Orie, one of the things that Mark mentioned is
that one of the reasons the robin was singing into the night is due to artificial illumination. So
over the last probably 200 years with the... Well, I guess even last 150 years with the birth
of electrification, how has that im
pacted circadian rhythms?
Orie Shafer: It's been an extremely recent and profound insult
to the living world. So as recently as 1950, only about 50% of the households in the United
States were electrified. It's only about half the households as recently as 1950 had access
to electric light. So ancestrally all animals, including human beings, evolved with a clear
indication from the environment what time it was. Our days were very, very bright. So even a
fairly bright-seeming cubicle during
the day is a couple log units less light than we would get
even on a cloudy day outside. So we're getting a lot less light at night, and we're getting
a lot of light... Sorry, we're getting a lot less light during the day and we're getting a lot
more light at night. So cheap electric light bulbs are one thing, but the devices are another.
And so basically we used to have this very, very high-amplitude clock-like oscillation
between a very, very bright day and a very dark night. And that's b
een fundamentally changed
over larger and larger areas of the planet. And it's having a negative effect on pretty much
anything with a circadian clock for sure. Joshua Brumberg:
What are some of the consequences for birds or other organisms
for the breakdown of the circadian clock? Orie Shafer:
Do you want to speak to birds specifically, and I can talk more generally after?
Mark Hauber: Sure. So changing whether or not you migrate,
when you migrate are all aspects that we care about. I was a
ctually biking on the West
Side Highway, well, not on the highway, but on the bike track the other day, and people
were taking pictures of something. And then I heard a mockingbird singing in the middle of
February in New York City, which would have never happened decades ago. And so I stopped,
of course, and was listening to the mockingbird for a while. But in Europe there's really clear
examples of things stopping to migrate. And we know that migration is driven by light cycles, not
nece
ssarily by temperature. And so short-distance migrants are more amenable to change their
migratory behavior, which if you read the book, you know that I love brood parasites like common
cuckoos, which are long-distance migrants. And so when the cuckoos come back, by that time, the
short-distance migrants have already started breeding, and so the cuckoos don't have a nest
to lay their eggs in. And so you have further decline of long-distance migrants because
of this mismatch between migrator
y times. Orie Shafer:
And speaking more generally, so a fundamental feature or a characteristic of
a circadian... So the word circadian comes from about a day. It means almost a day. And so
a defining feature is if you look at, say, perch-hopping rhythms of a bird, and you bring
that bird into the lab and you put that bird under constant dim light, so there's no temporal cue,
there's no lights on, lights off to tell the bird what time it is, it will continue to have a daily
rhythm in its pe
rch-hopping rhythm, a very clear rhythm. There's clearly a day for that bird when
they're hopping on the perch and a night when it's sleeping. But if you look at the actual timing of
that rhythm without the cues from the environment, it's slightly different than 24 hours.
So many birds have circadian rhythms that run, say, at 23 and a half hours per day, per internal
day instead of 24.0 hours of the solar day. And so what that means is that if you have a circadian
clock that is precise but i
naccurate, it runs too fast or too slow, we rely on light to reset those
clocks. And light is the most potent way to reset those clocks. And so this is really working havoc
on our schedules, something we call chronotype. You mentioned your chronotype and your graduate
students' chronotype in the book. So when we like to get up in the morning and when we like to go
to bed, as it turns out we're all becoming later and later and later types as the years pass.
And that's because our light enviro
nment is getting really bad at telling our clocks what time
it is. And so all of these interesting rhythms, so the secretary bird knowing when to go out and
kick those snakes to death, that's a product of the circadian clock telling it to get ready to do
that. Well, that rhythm is not going to be what we call entrained as well if that bird is exposed
to artificial light at night, and that's going to fundamentally change its daily timing and possibly
do so to the detriment of that species. J
oshua Brumberg:
We see in humans that people that are night owls or morning people, and
so there's variety within an individual species. Is there a variety like that within birds,
or is that something unique to humans? Mark Hauber:
I don't know. As a scientist, you have to say I don't know when you don't
know or when nobody knows. And so I think if you have pets, you know that they adapt to some
of your timetables. And so if you were comparing a cockatiel and somebody who's a morning
person
versus somebody who's a night person, they probably have a different rhythm. So I would
think it's out there. But I have a chapter on the dawn chorus, and it's important for everybody
to participate in the dawn chorus because the females are listening. And so if you're a male
and you're not participating in the dawn chorus, you're going to miss out on some opportunities.
It's also the time when there's perhaps less environmental noise through wind or through other
animals working or vocali
zing in the habitat. So I think that some times are important. The cowbirds
actually make use of the consistency of their host laying their eggs maybe 10 minutes after sunrise.
And the cowbird comes in about five to 10 minutes before sunrise, and it's important for the
cowbird to sneak in her egg before the host does, because if the host sees the cowbird, she will
abandon the nest or beat up the cowbird. And so those cowbirds have to have a very precise
timing. It also tells you that the cow
bird has to remember from the previous day where the nest
is, because it's pitch dark when she's coming to find or it's pitch dark when she's flying into
the forest and looking for a nest. So in fact, female cowbirds have large hippocampal volumes,
which is the brain area responsible for spatial memory. And so the timing of the egg laying
and the spatial memory work hand in hand. Orie Shafer:
So you mentioned this question of whether this chronotype issue holds
for animals as well as human
beings. And the human system is actually quite instructive here.
So the vast majority of us have a chronotype, a timing that actually does not fit anymore with
school and work times. The majority of us do not have a clock that allows us to get, say, the eight
hours of sleep that we need every night to be up by school and work start times. So as I said,
human chronotypes are getting later and later and later, and that corresponds with spending less
and less time outside, more and more time i
nside, under artificial light. Well, Kenneth Wright
did a wonderful study with human beings where he looked at human beings in a city, and they had
the full range of human chronotypes. There were early types and middle types and late types.
So then he did the experiment and he took them all camping for a week. And lo and behold,
when they were living without electric light, they all became early types. So really early
types is our ancestral way of timing things, and if we give ourselves an a
ncestral light
environment, we become early types. And so the best guess is, based on the human data, are these
bird populations that are exposed to strange light environments might very well display a wider
range of chronotypes like the humans do. Joshua Brumberg:
In explaining the situation with the cowbird, Mark, you talked about a brain
specialization. Are there other specializations for birds that are more nocturnal versus
birds that are more active during the day? Mark Hauber:
Definit
ely. So obviously eye size is going to be relevant. Most birds can't just
hear their way through the environment. They have to see a little bit. Migratory birds have larger
eyes than non-migratory birds, and some birds are olfactory driven. So I've got a chapter about the
kiwis, which have the nostrils at the tip of their beaks to be able to probe the ground and sniff for
earthworms. And so their olfactory bulb is much larger than, for instance, a chickadee's olfactory
bulb. The funny thing
is that chickadee relatives, such as blue-tits in Europe, are still using
their olfactory systems. So we think of brain area as sort of an indicator of functionality,
but even a tiny little bit of a brain area can still do a lot of function. And so if you
walk away with nothing but knowing that birds can smell from this lecture, I've done my job.
But there are obviously hearing specialists, song centers, so we know it from canary, from Fernando
Nottenbohm's work at Rockefeller University, a
nd a lot of other people working. So canaries and
other seasonal singers grow their brain areas that are responsible for singing the HVC, for instance.
Actually, Michael is a specialist now. He's at NYU, sitting in the front row here. So these
brain areas are responsible for singing, and when the bird is practicing its next-season songs,
the neurons are forming all kinds of connections. And when the song sets, the brain area shrinks
a little bit to save some energy. Brain is expensive energ
etically, and singing is expensive
energetically. And so these areas that have to do with acoustics, with vision, with olfaction,
with hearing are all important for birds. Joshua Brumberg:
All right. One other question about birds and in training to the time is what happens when
things go awry? There's been examples of natural experiments. A few years ago there was a massive
earthquakes, excuse me, volcanoes in Iceland, which created a gray plume across Europe, which
undoubtedly affected so
me sort of the light coming in and it affected the weather. Did that affected
the behavior of birds or other animals? Mark Hauber:
I was in Illinois in 2017 when the solar eclipse was happening, and you guys didn't
quite get the full effect here, but we drove four hours to southern Illinois, which is still the
same state, and the solar eclipse was complete. Joshua Brumberg:
You haven't driven to Buffalo. We can do nine hours and stay in the same.
Mark Hauber: That's true, that's true. I have
driven, and it
was a snowstorm and the PTSD has set in. But there I was, a total eclipse, and the starlings went to
roost, and the nighthawks came out at 4:00 in the afternoon. So it wasn't terrible, because the
solar eclipse lasted two minutes and then the nighthawks all went back to roost on the building
top. But you can see how the light cues were so important overriding some of the other internal
clocks in this particular case. But I think light pollution is definitely a major factor. A
nd
then how it interacts with the migratory times, and this connects with temperature regimes, for
instance, could be a major cause of mortality. Joshua Brumberg:
Are there any examples... You made the point, the barn owl is an nocturnal
animal because that's when its food is there, the small rodents it preys on. Is there anything
from the prey's perspective, well, they know that the barn owl is coming out, so they're going to
adapt their lifestyle to avoid the predator? Mark Hauber:
So the
re's a chapter on Cook's petrels, which is this small little
petrel. And until I worked with a larger petrel, I wasn't quite aware why what's going on. And
so the Cook's petrels are a gentle petrel. You can touch them and they bite you and
they don't cut off yet your finger, which is important for field work. But they are
being preyed on by larger sea birds. And so they actually end up using... They are active during
the day, they're out there at the sea foraging, but they come to land only
on the darkness because
they want to avoid the larger sea birds picking them off or the hawks and the eagles picking
them off because they are terrible on land. They crash through the trees, and they can barely
walk and then sniff their way to their nest, but they do it only at night because they are
so vulnerable to predation. So even a bird prey itself is going to change its behavior when it's
unable to run away or take flight. Imagine that you're in a mature forest in New Zealand and yo
u
crash through the canopy to land on the ground, you actually have to climb back onto the trees
to be able to take off flight again. But you typically live on an island with no rats and no
mammalian predators. And so it's the other avian predators you're trying to escape.
Joshua Brumberg: And how about other animals? Orie, do you
have any thoughts on that? Do other animals intentionally change their circadian rhythms to
give themselves an evolutionary advantage? Orie Shafer:
Absolutely. So
the clock is an amazingly powerful orchestrator of our lives, but all animals and
most organisms will throw that out when necessary. So for example, if you haven't had enough to
eat, so if you are starving in the wild, you will throw out that sleep-wake cycle in order to find
food. In addition, you do find that many animals are able to switch their temporal niche to take
advantage of opportunities. So if food is only available at a specific time of the day during
which you do not normally
eat, the animal will very rapidly employ their clock to anticipate that
new reality to get that food when it's there. So it's clear that the system is very accurate and it
continues to tick, but there's a really beautiful plasticity there that allows animals and plants to
take advantage of that internal temporal order to change their behavior when it's opportune.
Mark Hauber: If for instance, you want to watch kiwis in
New Zealand, you go to Stewart Island because on Stewart Island there's n
ot enough food for the
kiwis. And so they forage all day long as well as all night long. If you go to Tiritiri Matangi
Island, which is on the north of New Zealand, they forage at night because the earthworms
are everywhere actually introduced earthworms too. And so the Stewart Island kiwis are famous
for being sort of crepuscular and even daytime kiwis. And so that kind of shift from a purely
nocturnal organism to a daytime or crepuscular organism is eminently feasible. Now, you might
ask
the question, what preys on a kiwi? Why is it an nocturnal species? Remember, New Zealand
used to have these giant eagles that preyed on moas and other giant birds. Unfortunately,
neither the moas or the giant eagles, the Haast's eagles exist anymore, but the kiwis
are still maintaining their nocturnal schedule. Joshua Brumberg:
One of the things, of course, one of the most common things that birds eat are insects.
They fly as well. Or you study an insect model, Drosophila melanogaster, whi
ch most of us think of
as a nuisance, the fruit fly. But I think you have a little different perspective on that.
Orie Shafer: Yeah, so the only reason we understand the
molecular basis of a bird's clock is because we discovered, not me, but we as a field discovered
a molecular clockwork in the fruit fly. So these were based on simple genetic screens for mutant
flies that had a messed up clock. That led to the discovery of a very small number of genes,
and versions of those genes are tickin
g away right now in the hypothalamus of your brain
and in the hypothalami and pineal glands of birds all over the world. So the fly was really
a unique opportunity to discover the genes that make up our clock. And luckily for the three
Nobel laureates in 2017 working in the fly, those genes are highly conserved. So we have a
version or multiple versions of each of those fly clock genes that time our behavior and physiology
as well. So the fly's been very good to us. Joshua Brumberg:
So the
mechanisms that govern our entrainment to light are very similar, whether we're talking
about flies, we're talking about birds, or we're talking about mammalians?
Orie Shafer: Actually, it's actually birds and flies and
birds and bees are much more alike than birds and mammals. So we are all descendants
of nocturnal mammals. So there was this, what we call the nocturnal bottleneck that
all existing mammals evolve from nocturnal mammals. And so that makes us very different in
some important
ways from birds. So for example, mammals have a pineal gland that makes melatonin,
that's a hormone of the night, of darkness, and birds have a pineal gland. It's very, very
important for their daily circadian rhythms. But the bird's pineal gland is actually directly
sensitive to light. The bird actually allows enough light into its brain so that the clocks
inside of its brain have access to environmental light directly. So they get their information
about light both from their eyes and fro
m deep brain photoreceptors, so neurons within the
brain that are receptive to light. Because we went through a nocturnal bottleneck as mammals, we
lost all of the extraocular, all the non-eye light input, we lost. So we as mammals rely completely
on the retina to know what time it is outside with regard to light. So there's a real fundamental
difference between birds and mammals that way. And the birds are very fascinating in that they
let the light into the brain and we don't. Joshua Brum
berg:
What happens in blinded individuals, whether humans, or I know there's some
certain blinded amphibian and fish species? Orie Shafer:
Yes. So the amphibians undoubtedly do just fine without their eyes, because they
have these other photoreceptors like birds do. The mammalian case is really interesting. So there
are forms of human blindness where you lose all of the rods and cones, the primary photoreceptors
for the eye. Surprisingly, you can be completely blind due to the loss of those
rods and cones, but
still your clock is able, in an eye-dependent way, to know what time it is outside based on the
light. And that's because, so everything your brain knows about what your eye sees are relayed
by a very specific kind of neuron called a retinal ganglion cell. And as it turns out, a very tiny
proportion of those are actually photoreceptors themselves. This was a huge surprise, a really
fundamental shift in our understanding of the eye. So if you lack all retinal tissue, then
you
what we call free run, you show that non-24-hour, you come in and out of phase with the world.
If you have the retinal ganglion cells, even though you don't have rods and cones, you
can still synchronize your clock pretty well. Joshua Brumberg:
Ponder that for a second. But one of the things that we read more and more about is
the idea that we're going to explore space. I know this is a far-out question, but we're going to
now maybe colonize the moon or sometime down the road colonize
Mars, which is going to have a
different hour day. I don't know what they are on those planets. How is that going to impact the
circadian rhythms of the individuals living in those situations?
Orie Shafer: Well, it's really interesting. So the initial
experiments that tried to allow the human clock to free run, in other words, to run without the
influence of the environment, this took place, this was a work by Jurgen Aschhoff in the
Andechs bunkers in Germany. And so they put German undergr
aduates down in these World War II
era bunkers and tracked their sleep-wake cycles. And those students ended up showing days that were
about 25 and a half hours long. That's closer to a day on Mars, which is around 26. Now, as it turns
out, we know that the human clock is not quite that slow. This was a product of both the slow
clock and the students' use of the lights. But the fact of the matter is we'd be fine on Mars.
Our clock we know can entrain to a 26-hour day. That's not too far. So
the clock is because
of its sensitivity to light and other cues, you can push it to 23, 25, 26, but there are
limits. So it will depend completely on what that planet's periodicity is and whether or
not our clock can grab onto that cycle. Joshua Brumberg:
I mean, we've all experienced jet lag when we go from place A to place B. Birds,
as you mentioned before, Mark, go for very long migratory journals. Do they experience something
similar, or are they immune to jet lag? Mark Hauber:
You ask
ed the second question to which my answer is I don't know.
Joshua Brumberg: We didn't do this ahead of time.
Mark Hauber: A bird, imagine you're leaving from Alaska,
right? You're a bar-tailed godwit, and you're flying straight to New Zealand in seven days, no
stopping, right? Then you go from the end of the summer to the end of the spring in New Zealand.
And the time period is different. You have to fly through because bar-tailed godwits are not landing
on the ocean and refueling or anythin
g like that. They fly direct. And so you end up in New Zealand,
but then you're starving. You don't have a kidney left, you don't have barely any liver left. You've
metabolized all your muscles except for the flight muscles. And so all you have to do is just eat
all day long and all night long. And that's exactly what bar-tailed godwits do when they land
in New Zealand. They just consume as much food as possible at daytime and nighttime.
Joshua Brumberg: Truly amazing. So now want to open up
to
a few questions from the audience. Jimmy is somewhere. Did I surprise Jimmy? Oh, here he
is with the microphone. Please wait until you're holding the mic, because we want to make sure our
audience on Zoom can hear your question as well. Here and then...
Speaker 4: Hi. I think we're all familiar with the fact that
just before an earthquake event, you start hearing dogs barking, maybe cows mooing. Does something
similar happen with birds? Are they aware of things that are happening underg
round?
Mark Hauber: We think that birds can hear probably infrasound,
and so I think if there's vibratory signals, they could probably pick some of that up. My
own PhD advisor worked on celestial navigation in migratory birds, where we know that polarized
light matters, sound matters, of course memory of geographic features matters. Olfaction matters
in pigeons in Italy, but not in Ithaca, New York. Don't ask me why. And so I think that there
is definitely cues that the birds can pick up al
ong the way. And I think the images I'm thinking
about is large flocks of birds taking off as some geographic or geologic event is happening.
Joshua Brumberg: Right in front there. And then
we'll go to the other side. Speaker 5:
Do we know how much birds learn from each other or from their parents versus instinctual behavior?
Mark Hauber: Very much. Song behavior is almost a wonderful
model system for human speech. Birds imitate their tutors. They also invent a little bit. But
hearing a fath
er, hearing a sibling, hearing a neighbor is important, both for males, who in
zebra finches, for instance, are the singing sex, and females who make those choices based on the
male songs. Cardinals learn differently from their tutors if they're females compared to when they
are males. Birds can learn about the identity of cuckoos and the color of cuckoo morphs from their
neighbors. So birds learn a lot socially. In fact, social learning and socially-mediated learning
is the next hardest th
ing in bird research. One of my PhD advisors, Steve Emlen, used to
say, assume that birds know everything that as a scientist, and that should be the beginning of
your investigation. And so I really live by that, because we often say, "Oh, birds invented
something," or, "Birds were able to open the trash cans in New Zealand or in Sydney." And
those are just natural things that the birds apply to artificial stimuli. They are opening
strange nuts and fruits that have hard coverings. It's not
surprising that they can also open
things that are made of plastic. And so they're terribly inventive, but they're also terribly
imitative. And so the answer is definitely yes. Speaker 6:
Two parts to my question. You mentioned that obviously light is a way that really sort
of messes up circadian rhythms. I know that sound is also, in modern world, is a huge factor
with industrial noise. Maybe could you comment on how sound is being understood as disrupting
our world is in addition to the l
ight changes? The second part of my question is, I know, Mark,
you've talked a lot about some of the architecture of how tall buildings are really difficult for
birds to navigate with. The World Trade Center has a huge number of birds that fly into it
and are killed on a daily basis. Can you give advice to any of the architects in the room as to
things we could do to mitigate those behaviors? Mark Hauber:
So a couple things, and I'll also yield to Orie. So noise is of course an incredible
a
spect of our environment, and we know that birds that live near streams sing at different
tunes than birds that don't live near streams, waterfalls, and of course urban noise. There's
a really famous early 2000 paper on great tits, which are chickadee relatives, in Europe singing
at a higher pitch in Amsterdam than in rural Netherlands, if there's such a thing as rural
Netherlands. So they elevated their songs about half a kilohertz or something like that. How do
you make this into an exper
iment? Well, you wait for a pandemic. And so there's a famous science
paper from the San Francisco region to show that when people stopped driving on the streets
and public transportation stopped functioning, the birds were singing at lower pitch because the
urban noise was not drowning out their songs. My favorite example, and I just thought
about it, is Tempelhof, not Tempelhof, Tegel airport in Berlin. So people collected data
on the airport near the airport and far away from the airport
, and published it in a second-level
journal that the birds near the airport sang at different times of the day when the planes weren't
flying. Now, Tegel airport was shut down in favor of a terrible airport in the south of Berlin,
and the birds are now singing all day long, and they're singing at lower pitch. And that paper
made it into the bigger journal because this was a quasi-experiment. Regarding the architecture, we
now obviously have a bird-safe window requirement in New York City,
and it's a lot of barring on
the windows that need to be done. But I think the most important thing is turning up the light at
night. So your office, when you leave the office, the lights should automatically turn off
after 20 minutes of no movement or something like that. And then the birds will not be
flying towards the buildings as well. Orie Shafer:
In terms of environmental sound, you can use sound to entrain a circadian clock if there's
no other cues around. But the circadian system i
n an environment that has light and temperature
changes wouldn't be too influenced by the increase in sound, but it's certainly conspiring a lot of
sound at night is certainly further deteriorating our sleep. So one of the main problems with
clocks in a modern world is we're not able to sleep as long as we need to be up for the social
clock the next day. So that, plus noise at night, is certainly not a good combination for
the quality and duration of our sleep. Speaker 7:
I had a question a
bout the IQ of birds. Is there some birds are smarter,
a lot smarter, significantly smarter than others? And how do they show that?
Mark Hauber: Yeah, so I have a colleague who, so everybody
studies corvids, right, for intelligence? Crows and magpies, and of course parrots. Keas in
New Zealand are famous. Cockatoos in Sydney are famous. And so I have a friend who studied
grackles, because grackles do kind of the same things as corvids do, they prey on nests and
nestlings, they look like cor
vids. They take up the niche of a corvid, perhaps. Grackles are
not smart. This was an entirely failed research program. They just can't solve anything. You give
them the string test, they can't pull it up. You give them some sort of a puzzle, they can't solve
it. I felt terrible. I really wanted grackles to be both habitat wise and cognitively [inaudible
00:49:18] to the corvids. But they are not. What are smart are starlings, for instance. And
so the mynas that I mentioned earlier are inv
asive species on every continent from the
Pacific to New Zealand to Hawaii and Florida. And we had a grant to study them there and in
Israel. And so the birds that are at the front of the invasion front are actually much faster
in solving puzzle boxes than the birds at the beginning of the invasion, which was the
Tel Aviv Zoo. And you don't need to figure out what happened. The cage opened and the bird
flew off. Or compared to their native ranges in South Central Asia. And so the birds that
are
exploring new habitat are also better able to explore new foods. They're less neophobic. You
can give them different colored food items and they'll peck on them, which makes sense. And so in
fact, I compared mynas in a preliminary study and grackles, and the mynas were just all over the
place. They just wanted to explore everything. And the grackles were very conservative.
You have to pick your species, and you have to pick the context. Cowbirds are very good at
finding nests, but they
're not terribly good at spatial skills in the lab, which is too bad
because we wanted to study their spatial skills. Birds are really good at telling individuals apart
between their neighbors and their non-neighbors, the enemy effect, for instance. But they're
very good at telling colors apart, but not necessarily in a cognitive task, but they can tell
a brighter fruit item or a brighter flower apart from a duller one or a less ripe fruit item, for
instance. So you have to pick the context
in which you're asking the question. Jack-of-all-trades
is probably going to be some sort of a corvid winning out. We know that New Caledonian crows are
great at toolmaking. Hawaiian crows were probably toolmakers when there were lots of them still
flying around. So corvids and psittacidaes or parrots are probably up there.
Joshua Brumberg: We used to have a chicken that
played tic-tac-toe in Manhattan. Mark Hauber:
And obviously Flaco makes it in- Joshua Brumberg:
No one else remembers tha
t? Down in Chinatown there was the tic-tac-toe
chicken. Sorry, question. Oh, right in the back, and then we'll move forward.
Speaker 8: Hi. You talked about how temperature and light
tell us what time it is internally. Is there any evidence of other organisms sort of informing
our clocks, like the way birds maybe wake us up in the morning?
Orie Shafer: Oh, absolutely. I mean, it's the morning crow. The
cock of the crow is the classic. And I think that the bird song in the morning is such a v
isceral,
beautiful indication that it's time to wake up. I mean, you can't think of a better way to wake up
than that. And as you point out, it does seem to be a morning gig. It goes away pretty soon after
dawn. So I think we've relied on cues like that for a very long time. I don't know about other
animals. What do you think of other animals? Mark Hauber:
I'm trying to think of anyone being woken up by another species.
I don't know. Sure, that's right. So howler monkeys are great because a
nytime they go to the
bathroom, they vocalize. And so I actually had... My PhD advisor's son was a famous researcher, Doug
Emlen, who studied horn beetles. And so he needed to collect high-quality poo for his research
because the horned beetles grow a longer horn when they eat high-quality poo. And the howler
monkeys were his source. And so he would be ready every morning the howler monkeys did their thing
to run out and collect poo from this Panamanian island. And it turns out it's a valua
ble resource,
because if he was too slow, the other dung beetles would have already taken everything away. So
the tropics, everything is a competition. Joshua Brumberg:
Right here along the aisle, Jimmy. Speaker 9:
You mentioned that some birds have a part of the brain that can detect light,
and I just don't understand how the light gets to it that it can detect it.
Orie Shafer: Yeah, it's really fascinating. And this is true
of most insects as well. So enough of that light will get through
the feathers and the skull. So
there's some really famous work by Mike Menaker who was investigating fly, sorry, I'm a fly guy,
bird entrainment, so how the bird could latch onto light-dark cycles. And what was interesting is
when they reduced the intensity of the light, so you have 12 hours of light and 12 hours of
darkness, and you're seeing whether that bird can latch onto that cue and entrain to that 24-hour
day. Well, when they dimmed the light enough, the bird could no longer entrain.
And all Mike had
to do was pluck a few feathers out of the top of the head above the pineal, and all of a sudden
the bird's brain could detect that light again, indicating that there's just enough light getting
through on a bright day. Now, a bright day, even a fairly dim day outside, that's a lot of
photons, and some of them are going to get through the skull and into the brain.
Joshua Brumberg: And the birds opposed to our
skull, which is basically solid, the bird's skull is much more li
ke a honeycomb.
That's more for weight reasons so it could fly, but it's much more translucent.
Mark Hauber: Yeah, I was going to say that. So birds have
two things. One is they have feather tracks. So not every piece of skin is covered with feather.
And so if you blow on the head of the bird, you can actually see this honeycomb brain structure
that made of two layers of thin, but structurally sturdy components. And as the birds grow older,
the second layer ossifies, and you can actually te
ll whether a bird is the same year as you catch
it in the fall versus an older bird by blowing on the head and figuring out if there's ossification
in the skull. And so bird banders figure out if somebody is a young bird or not based on that.
Joshua Brumberg: All the way in the back, Jimmy.
Speaker 10: Hi. I teach industrial design at Pratt
Institute, and every year in the fall, the sophomores are supposed to study birds and do
a bird house for them. And this year the students said they didn
't want to do that. They wanted to
study how the birds made their nests. And I said, "Okay, let's see if we can learn anything from
the birds." So we started looking how birds create their nests, and we all think they're all
the same, but it seems to me like we learned how to weave from birds. And there's the tailor bird
who actually sews leaves together. And then there are birds in many parts of the world where they
make adobe houses. So do you think we actually learned how to do those thi
ngs from birds? They've
been probably doing it longer than we have. Mark Hauber:
I hope so. I mean, an ovenbird or the hornero in Argentina builds
this wonderful structure that actually is pitch dark in the middle. And so we use that bird to
ask questions, how do you tell a cowbird egg apart when you live in an entirely pitch dark house? And
the answer is shape. Look at size and shape and tactile sensation. But we also found, so I have
a new gig on writing about nests now, because the nests
of most of the 10,000 bird species have been
described, and the databases are out there. And so you can ask comparative questions about let's
compare 6,000 birds doing this to 4,000 birds doing that. And so we know that the eyes of the
birds that are weavers amongst the weaver finches, for instance, are larger compared to the more
simple nest-building ones. So there's nice co-evolution between the sensory organs and
probably the beak structure, as well as the ability to weave really delica
tely.
Speaker 10: I have one tiny more question.
Mark Hauber: Sure.
Speaker 10: I think I read this on Instagram, but I always
thought that flowers opened up in the morning because of sunlight, but apparently the studies
say it's from birds singing in the morning. Do you know anything? Can you comment on this?
Orie Shafer: Yeah. So it really depends from species to
species. And so the flowers come from such a diverse array of plants that plants have very
different approaches to this. So we r
eally, arguably the field of chronobiology, the study
of biological time started with plants. And so it was the realization that plants undergo these
leaf movements. They were actually called sleep movements at the time, that they kind of droop
down at night and they kind of stand at attention during the day, and that flowers open and close
at specific times. And so for some plants that's strictly a rhythm. It's a rhythm driven by an
internal clock. Others are responding directly to the sun
light. And others had some combination
of the two. And it would not surprise me at all if some species of flowers have found different
cues to open up at the appropriate time. So Carl Linnaeus, how do you say it?
Mark Hauber: Linnaeus.
Orie Shafer: Linnaeus. He actually invented something called
the flower clock. So you can can find a species of flower that opens at a specific hour of the day,
much like the birds that Mark wrote about. And so he had envisioned a garden, a circular garden tha
t
you could plant so you could look at and see which flowers were open and thereby detect what time it
was. Unfortunately, they don't all flower in the same season, so it never would've worked out.
Mark Hauber: But there was a special article of behavioral
ecology, which is typically about animals, about auditory perception in plants. And so
it's not that far of the deep end for sure. Joshua Brumberg:
Up here. Speaker 11:
Can you describe some of the methods that you used to derive your info
rmation and
reach your conclusions in writing your book? Mark Hauber:
Sure thing. So for the birds that I studied, I sort of wrote a bunch of papers on them and I
tried to summarize the information. The birds I didn't study, like the secretary bird, I went to
the original literature, so primary literature, like Current Biology that had a really nice cover
article about the secretary bird's kinematics of kicking. And so I always try, even in the egg
book, there was like 600 species, I try to
get two sources of peer-reviewed literature piece
that I end up writing a story about so that we can go back to the scientific literature to
validate the stories that I end up writing. But for the species that less is known, such as the
night jar, I looked at photographs, I looked at descriptions of birding trips where people have
described behaviors in a direct way, because some of the birds in the book weren't that well
studied, but I still found them fascinating. Speaker 11:
So you look
ed at other people's works. Did you do some of your own work, just an experiment?
Mark Hauber: Oh, sure.
Speaker 11: Could you discuss some of that?
Mark Hauber: Yeah, so the cowbirds, my lab is called
the cowbird lab. And so we've published on cowbirds birds, say, 150 articles, something
like that. And so we know when cowbirds wake up, we know when cowbirds go to sleep, we know what
eggs they lay, we know how the hosts respond to the eggs. So for instance, I use 3D printed
eggs to ask quest
ions how the robin rejects the cowbird egg. Is it shape, is it color, is it
scent? Is it tactile stimulus? And so we've done all those experiments. The one thing about
Illinois that was not boring was the study system. I worked five miles from my bed in a tree
farm where the robins were nesting everywhere. And so we had 400 nests available to us in every
single season. And so you put a 3D printed egg of a different color, a different shape into
those nests, and then come back the next day a
nd ask the question, is this egg still there? Or
videotape the bird's behavior. Or what my student Abby Turner invented is put a radio into the
egg, into the fake egg and then see where the robin takes that egg. And does that depend on the
color or the shape or her hormonal status? So we manipulated corticosterone levels in these birds
by putting jelly onto the eggs and infusing with corticosterone, because we found that even though
robins live with us, the moment you catch them, the moment
you inject them with something,
the moment you put a color band on them, they will hate you. They will despise you. They will
not like you ever, and they will remember you. If you have a robin nest on your summer property
or your vacation home, you can open the door. Nothing happens. The robin sits on it. The moment
I have caught that robin and put a color band on it to be able to identify it for the future, that
robin will fly away 50 yards away when she sees me. And so we didn't want to
do that. We wanted
to do experiments that disturb the birds as little as possible. And so looking at hormone levels
sort of indirectly was a way to ask questions scientifically.
Joshua Brumberg: Thank you. All right. This is unfortunately going
to be our final question. We'll go up front here, or we already have one there. Go ahead.
Speaker 12: I observe birds in the courtyard through my
window, and there is a hawk and there are mourning doves and they are very methodical. There is a
rhythm
throughout the day, but I always wonder, are any procrastinators among the birds?
Mark Hauber: So I will say that robins are terrible at
chronobiology, because I used to go out in the field at 5:00 in the morning, 5:30 sunrise. I'm
done by 10:00 because it's super hot in Illinois. My student Sarah, they didn't go out until noon.
They were an afternoon person. And so I would say, "Sarah, here's a nest with two eggs in it." And I
would mark them one and two, just little numbers with a felt ti
p pen. Sarah would get to the
nest at 5:00 in the afternoon, it has three eggs. And so that robin laid in the middle of
the day. And in fact, there's a study out there when do robins lay? And it's unpredictable.
They can lay anything from first thing in the morning until very early afternoon. I mean, the
distribution is insanely broad. The tails are super long. If you look at a chipping sparrow or
a prothonotary warbler, they lay 10 minutes after sunrise and that's it. You can catch the bird
by
being at the nest 10 minutes after sunrise. So the robins are definitely procrastinators. They're
weird on so many levels. I love them very much, but they are just weird. Joshua Brumberg:
Well, thank you. We love talking to you, Mark, and to you, Orie. We hope you enjoyed your Valentine's Day with us, and we hope that you spend some other evenings with us this semester when we really span the disciplines from Lou Reed to modern economics, and everything in between. So we hope you join us a
gain in our public programs. Thank you and goodnight.
Comments