June 26, 2025 • 33 mins
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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. Robert Lamb.
Here in today's episode, I'm going to be chatting with
Rosalind Dakin, Associate professor at Carlton University in Ottawa and
principal investigator at the Dynamic Behavior Lab. We're going to
be chatting about hummingbirds, as she and her co authors
just had a new paper published in the Journal of
(00:33):
Zoology Turning trade offs. Hummingbird power reserves are used to
decrease turning radius or increase turning velocity. So, without further ado,
let's jump right into the interview. Hi, Rosalind, Welcome to
the show.
Speaker 3 (00:49):
Hi, thanks for having me.
Speaker 2 (00:51):
So we're going to be talking about hummingbirds today. We're
already really enjoying the company of hummingbirds down here in Atlanta.
Have they arrived up there where you are? Yeah, you're
in Ontario?
Speaker 3 (01:02):
Correct, Yes, exactly, I'm in Ottawa, Ontario. And they arrive
the first week of May the ruby started. Hummingbirds show
up almost like clockwork every year.
Speaker 2 (01:11):
It's always a joyous occasion here at my house when
we finally see the first humming birds of the season
appear at our feeders and flowers, and I think, you know,
at first it's the magic of them being here, the
way they move and all, But as you begin to
observe them, you really begin to notice how intensely territorial
they are about their flowers or about the cute little
(01:31):
feeder we've put out for them. Can you tell us, like,
why are they so territorial about this? Sometimes as humans
putting out feeders, we want to tell them like, no, no,
there's plenty you can share, and they're generally not having
any of that.
Speaker 3 (01:45):
Yeah, that's right. They have super competitive behaviors, and that's
something that we've been studying in my lab. Why they're
like that, I think it all comes down to their
super high metabolic rates. Their lifestyle relies on having a
steady stream of calories throughout the day, and if they
(02:06):
go even an hour without feeding, depending on how much
energy fat store they have in their body, that can
be death an hour without a meal. So those food
sources are really really valuable to them, and their metabolic
rates are so high. If you could scale a hummingbird's
body up to the size of the average adult human,
(02:26):
it would be like if you or I had to
eat one hundred and fifty large pizzas in a day.
Speaker 2 (02:32):
Wow, Now how can their wings that move so fast
to repel thems of the air.
Speaker 3 (02:37):
Yeah, so in order to be able to hover, hummingbirds
have to beat their wings, depending on the species, between
thirty to eighty times per second. So if you think
about a full wing stroke, that's your arm being fully
extended back, coming forward, and then back again and repeating
(02:58):
that cycle. For species like ruby throated hummingbirds, fifty times
every second. It's incredibly fast. So they have so that's
why they have such high metabolic rates, the highest of
any vertebrate animal per unit body mass. But they have
a lot of anatomical adaptations that are required to be
(03:19):
able to do that. So for example, they're pectoral muscles
that draw the wings down that activate the downstroke are
hypercha feed. They're really really large. But similarly, they have
another muscle, the super corecoidous muscle that draws the wing
back up, and it's also hypercha feed. It's also extra large.
(03:41):
In hummingbirds, they have skeletal adaptations as well, so the
muscle that the bones that those muscles attached to have
to be larger and more robust than they are in
other birds that have more typical wing beat frequencies, and
they also have dramatically modified and that so the bones
of their wing, these are the bones that we can't see.
(04:03):
We just see the feathered part of the wing, but
inside the hummingbird's wing they're humorous is really really short.
It's so short, it's almost like a little dot, you know,
It's just a couple of millimeters in length. And their
their wing is mostly hand And what that does is
it means that the heavy parts of their arm bones
(04:25):
are drawn in close to the body to make it
easier to beat those wings so fast. But it also
means that those muscles that are activating those wingstrokes are
working over a shorter distance, and so that makes it
physically possible for them to beat their ways at this
incredibly high frequency.
Speaker 2 (04:41):
So what evolutionarily has driven this development this arm's race
of hummingbirds. Is it just their diet and how they
need to feed it, is it predators, is it other hummingbirds? Like,
how does it all come together?
Speaker 3 (04:54):
Yeah, that's a super interesting question and one that we
have hypotheses, but it's still an active area of research.
If we go back, well, let's start with looking at
what we have today. The hummingbird family is extraordinarily diverse.
There's three hundred and sixty six different species and they
(05:17):
live in the Americas, so South America, Central America, the Caribbean,
and subspecies here in North America. That's incredibly diverse, and
they've radiated, they've diversified into all of these species over
the past twenty five million years. And if we look
at their closest relatives in the evolutionary tree, the family
tree of all birds, those are swifts, which are also
(05:40):
super agile birds. They're distributed across the globe. We have
swifts in North America. We also have swifts in Europe
and Asia that are aerial insectivores. So swifts spend almost
all of their time in the air catching flying insects,
so they have to be like little fighter pilots to
(06:01):
be able to chase down their prey. So the first
hummingbirds evolved around thirty million years ago from an ancestor
that was a really really acrobatic predator in the air,
and swifts have some of the same skeletal adaptations that
we see in hummingbirds. They have an enlarged keel. That's
the part of the bone on the breastbone where those
pectoral muscles attach, and swifts also have changes in their
(06:26):
wingbones that we see in hummingbirds as well, So that's
part of how we know where the hummingbirds fit in anatomically,
but also genetic studies have established what those relationships are.
So yeah, the first hummingbird was something something like an
insective war chasing down insects, and somehow, you know, maybe
(06:46):
they started to prefer insects that were associated with flowers,
and maybe that led to them consuming some nectar. We
don't know exactly what happened to produce this fift towards
being so specialized on flower nectar. But the other mysterious
part is that the earliest ancestor, the earliest fossil ancestor
(07:08):
we have of hummingbirds is not at all in the
same part of the world where we have all of
the species that we can observe today. The closest fossil
ancestor of hummingbirds they come from Europe, so fossils with
a lot of those hummingbird typical features, a long bill,
an exaggerated keel, and different wing proportions. Those have been
(07:31):
found in Poland and in France and multiple places, so
they arose in Europe we think, and at some point
made their way over to the Americas thirty twenty five
million years ago and from there diversified into very many
species day and a lot of that is the diversification
is probably due to specializing into different areas in the
(07:56):
Americas and in the Caribbean.
Speaker 2 (07:58):
So they're enhanced maneuver built in their power reserves, which
we're going to get into when we start talking about
your study here. This is largely for inter hummingbird competition
or do they have aerial predators they need to worry
about as well?
Speaker 3 (08:14):
They may have some effective predators. That's not something that
we observe very often, but we see a lot of
competition both between species and also within species, so especially
among males within a species, competing for a territory, competing
for a food resource. The other area where we see
them using their acrobatic skills is when they're courting mates.
(08:38):
So in very many species, the males will try to
impress females by doing an elaborate display in the air,
and the way that display goes will differ in different species,
but often they're zooming back and forth, reaching really high
speeds and turning quickly as part of that display, all
at the same time as they show the female their
(09:00):
colorful plumage and sometimes like make certain sounds while they're
doing those as place as well.
Speaker 2 (09:13):
So getting into your research a bit more here, tell
us a little bit about the Dynamic by Behavior lab
and how hummingbirds factor into your work there.
Speaker 3 (09:22):
Yeah, so we are interested in differences between individuals and
differences between species and when performance is such an important
part of how they survive, how is it that, like
what determines which individuals are dominant over which others, who's
winning those competitions, what traits determine who wins, But also
(09:45):
for individuals that are subordinate, what options do they have?
How do the subdominant individuals make a living? Those are
some of the questions we're studying in my lab. So
we measure things like they're an individual bird's ability to
generate power in flight, and we also measure their behavior
in big arenas where we can pit multiple birds against
(10:07):
each other competing over a food resource and seeing both
who's dominant, but also how are they using flight maneuvers
to outdo each other.
Speaker 2 (10:17):
Now, how do you go about studying something like this,
because hummingbirds, i imagine, are not easy creatures to study anyway,
and then you're dealing with some difficult to measure properties here.
Speaker 3 (10:26):
Right, Yeah, it takes a lot of patience. And one
of the nicest assays that's possible to do with hummingbirds
is a load lifting assay where we can measure the
maximum power they're able to generate with their flight apparatus,
with those muscles that are activating the wings. And we
do that assay in a chamber that's think of like
(10:50):
a vertical cylinder with kind of an open bright light
at the top, and a humming bird at the bottom
of that chamber is going to be highly motivated to
upwards try to escape, and we use an assay that
was developed decades ago by other scientists where we put
a little ring around the bird's neck that's attached to
(11:13):
a string of beads, and when we know the weight
of the beads along that chain, we can record what's
happening when the hummingbird gets released from the bottom of
the chamber. And if everything is set up suitably for
the bird as they try to escape upward with everything
they've got, we're able to measure exactly how many weights
or how many exact weight of the beads on that
(11:33):
chain that they're able to lift. The higher they go,
they're lifting more and more weight until they hit a
maximum and return back to the bottom of the chamber.
So we're able to develop an assay that just fits
with their capabilities their motivations to measure their maximum weightlifting ability.
Speaker 2 (11:52):
So essentially the tiny necklaces on hummingbirds is a part
of the study exactly.
Speaker 1 (11:57):
Yeah.
Speaker 3 (11:58):
Yeah, so we have to make those necklaces. Yeah.
Speaker 2 (12:00):
Wow. So this this latest study published in the Journal
of Zoology, really gets into their their maneuverability and their
power reserves. Can you lay out how these these two
aspects are linked. As I was reading the paper, I can't.
I really kept thinking of hummingbirds in like video game
terms and imagining like little meters at the top of
the screen.
Speaker 3 (12:19):
Yeah. So a couple of questions motivated this study, and
it was led by my colleague Paulo Segre and my
co author Doug Altuler. So one of the questions was,
when we're measuring their maneuvering performance, which includes lots of
complex behaviors that have a lot of degrees of freedom.
(12:42):
How tightly can they turn, how fast can they move
when they're turning, How fast can they accelerate decelerate? When
we're measuring those maneuvers, it's really hard to capture what
is a bird's maximum ability? The more freedom you give
them in a space where you're capturing what they do,
the less well defined maximum is because there's so many
(13:03):
different ways to move in a completely open environment. So
we've been studying maneuvering ability in across the different hummingbird
species for some years, but we wanted to know is
the power they're able to generate in a more constrained
assay like our low lifting assay, is it predictive of
(13:24):
some maximum that we're able to capture in this free
flight assay. That was the motivation for that study, so
led by Pollow. What Pollo did was he reasoned using
fundamental physics that one of the basic maneuvers that they
use very frequently to turn, which we're calling an arcing urn,
which is basically just a level turn that if you
(13:47):
look at it from above, you follows a smooth arc.
He reasoned that those arcing terns that we can build
a physical model of the forces that they need to
to produce those arcing turns, and we can test whether
(14:07):
the maximum load that a bird is able to lift
in our low lifting assay does that correspond with the
maximum that they're hitting up against as they redirect forces
during those arcing turns.
Speaker 2 (14:21):
So one of these arcing terns you're describing here, would
this perhaps be one of these maneuvers we see when
one hummingbird chases another hummingbird away from a feed or
flowers in our yard.
Speaker 3 (14:33):
Yes, absolutely, yeah, and yeah, definitely they'll use arcing urns
during chases. They'll also use arcing turns during obstacle avoidance,
which is really important to a fast moving animal. Those
collisions could be deadly.
Speaker 2 (14:48):
Yeah, these the collision avoidance turns. I guess I don't
notice as much because if they're avoiding collision with my head,
it's all happening so quickly. But yeah, but sometimes we'll
be watching them off, and we'll be watching them and
we'll see one chase the other off, and it sounds
like that's what you're talking about here.
Speaker 3 (15:05):
Yeah, exactly.
Speaker 2 (15:06):
Yeah, I'm sorry, but I got us off topic here.
You were describing your analysis of these turns.
Speaker 3 (15:13):
Right, Yeah, So in those free flight essays, we aren't
telling the birds what to do. They're performing at a
sort of routine flight level of performance as they're trying
to avoid the threatening experimenters avoid collisions with the size
of the flight chamber. But we can capture thousands of
(15:34):
maneuvers from each individual over a relatively short span of
time because everything hummingbirds do just happens on much faster
timescale than other species or than their own lives. So
if you record a hummingbird for two hours, you might
capture two thousand arcing turns, for example. And so we
can computationally pull out the segments of flight that represent
(15:56):
the arcing turns that we're limited to a level plane,
and we can apply the physical model that Paolo built
to say, okay, the redirection of forces as the bird
is banking its body to execute that turn, what's the
what's the kind of space of what that looks like
(16:17):
for the many, many thousands of turns that we captured
from the different humming birds in our study. We studied
about twenty individual hummingbirds in that study. And does the
does the limit of that, but distribution, how does that
align with our predicted limit from how much weight those
birds could lift in our highly constrained load lifting assay,
(16:41):
And what we found was that overall, collectively, the model
predicts really well the maximum turning performance of the birds
in that chamber. So the Anna's hummingbirds that we study
either from the west coast of North America slightly larger
species than we have here in Ottawa or where you are,
(17:05):
but they have in our little lifting I say they
can lift about two and a half times their body
weight on average, and we can model what that would
translate to in terms of being able to redirect forces
to execute that turn. And the birds in our free
flight experiment, their peak performance matches that peak of what
(17:29):
we would predict based on their maximum ability. So it's
really satisfying. It It aligns with our hypothesis that in
order to be maneuverable, that power has to come from
their muscle capacity and flight and their kind of excess
muscle capacity. Their ability to just lift weights vertically is
going to determine how well they can execute these high
(17:53):
performance acrobatic maneuvers.
Speaker 2 (17:55):
So as they're flying about during the day, like how
often are they like at absolutely using up their powers.
Speaker 3 (18:02):
Yeah, that's a really good question that we don't know
the answer to yet. And how often are they hitting
their maximum out in nature? Probably not that often compared
to you know, when you think of like the lifespan
of a hummingbird and and how much they do during
it during the day, I would estimate, I would hypothesize
(18:23):
that it's it's pretty rare that they're executing maneuvers that
are that are hitting their max. But in our flight chamber,
you know, it was a pretty small proportion, maybe one
percent of the turns are kind of hitting that maximum envelope.
And and maybe it's similar out in the wild. But
that's something that we'll be able to test in the future,
(18:46):
for example, by having sensors small enough to put on
a really small bird. That's kind of the challenge there.
But a lot at the time of the like you know,
a lot of their time of the day they spend
perching and and probably one of the biggest challenges for
them is maintaining the muscle mass that they would need
(19:07):
to execute those rare super high performance maneuvers.
Speaker 2 (19:11):
That's absolutely fascinating. Now I have I have another question
or two about just studying the hummingbird, Like we as
we observe them, you know, we we obviously pick up
that they are they're very powerful creatures in their own right,
(19:33):
but we also get the sense of fragility about them.
Are they are they fragile to deal with?
Speaker 3 (19:38):
Like?
Speaker 2 (19:38):
What how is it different dealing with hummingbirds versus other
birds you might be studying in your in your work.
Speaker 3 (19:46):
Yeah, I would say in the lab there their relatives
are easy to deal with compared to other species. And
part of that might be they're they're so specialized. If
you kind of know the conditions they need, they're relatively
easy to keep healthy. The main point of fragility is
(20:08):
that's super high metabolic rate. If they run out of food,
that's catastrophic. But if you've got the right conditions for them,
kind of unlimited food, the right physical space, they're pretty
easy to deal with in the lab. But we have
to cows them separately, and that's different than other birds because, yeah,
they're so aggressive. They they would exclude each other from feeding,
(20:32):
for example, and their bills can be a weapon. So
when when they're kind of housed in captivity, we keep
each individual on its own and you don't see it
that often in the wild. But but if you have
video footage, high speed video footage of birds interacting and
(20:53):
fighting at a feeder, you'll see how that bill is
really like a long dagger, and that they're they're facing off,
they're making sure they orient their bills towards towards each other.
You can imagine a collision with those long bills would
be really catastrophic for an animal that only weighs two
and a half grams.
Speaker 2 (21:10):
Oh wow, Yeah, that was going to be one of
my questions, like what is the We see them chasing
each other, like, what are they actually doing to each other?
If they catch it, it's kind of it sounds like
it's like a joust in a sense, right, yeah.
Speaker 3 (21:23):
And it's really hard for us to capture what that like,
what are the consequences of that in the while the
best examples we have are footage that people can capture
at a feeder and when birds really get into it
close to a feeder, what happens and you see them
grabbing each other's feathers and using their bills to defend
(21:43):
that space to displace another bird. And and there's still
a lot of open research questions about you know exactly
how like what what signals or outcomes are determining who
wins those competitions and and that's an active area of
work that we're studying now in my lab. But even
(22:04):
in the lab, we'll see them rarely make physical contact
with each other. So if one bird wants to displace
another from a perch, sometimes they'll get into little scuffles
where they're making contact, and I think at high speeds
those kinds of scuffles would be really dangerous to both individuals.
So it's a real game of chicken.
Speaker 2 (22:25):
Now, when you're studying hummingbirds, is it completely seasonal? Is
it seasonal availability very much a part of this or
do you have hummingbirds like in captivity that you can
study year round.
Speaker 3 (22:36):
Yeah. So in my lab here in Oddwell, we're studying
ruby started hummingbirds and they are migratory and so we've
been catching birds here since the beginning of May, and
we've got a group of males in the lab now
that will release again prior to their autumn southward migration.
So we're only working with them within the breeding season
(22:57):
here and only studying the males, and remarkably many individuals,
many of the migratory species, an individual humming bird will
come back to the very same feeder. So one of
the birds in my lab now is a bird that
we caught and released on campus last year. Attached a
(23:18):
little band to his leg with an identifying number, and
he would have migrated all the way to Mexico, and
then this spring, the first two weeks of May, like clockwork,
he showed up at the exact same feeder. We captured
him again this year. So it really is remarkable not
only the physical feats that they do, but also they
(23:38):
have remarkable memories and that's all part of their high
metabolic rate. They need to know where those reliable food
sources are. So this male were bethowted humming bird came
back to the exact same feeder after this cross continental journey.
Speaker 2 (23:52):
That was going to be one of my follow up
questions about the what's going on in the mind of
a hummingbird, And it's because again, they just they're such
drastically different creatures. They're living on this time frame, you know,
that's so different from ours, and then vast distances in
addition to vast speeds, so we have what else do
we know about their about the way their little brains work.
Speaker 3 (24:15):
Yeah, it's really fascinating. So there's a lot of excellent
research coming out of my co author, Doug Altruler's lab
on how their brains work and how the visual system works.
And we also have studies of their spatial memory. And
so a really beautiful study from about twenty years ago
now on a species of hummingbird that lives in the
(24:37):
Rocky Mountains looked at their ability to learn flowers that
change in nectar availability through time. So real flowers are
not like feeders. Real flowers will be depleted and will
replenish themselves over some seasonal period. And hummingbirds that have
(25:02):
a territory with lots of flowers in them, they need
to know where their next meal is coming from, and
they're able to learn the locations of many flowers. As
an example, this bird that came all the way back
to my feeder from Mexico, he would have remembered other
places along that route, we hypothesize. So what the researchers
(25:26):
did in Alberta, Canada was create an experiment where they
could track one male in the wild who had a
territory and they had dynamic feeders in that territory that
went on different time schedules. Maybe some feeders would replenish
on five minute intervals, others on ten minute intervals, others
on twenty minute intervals. And if a bird had multiple
(25:49):
of those variable timed feeders available, would they be able
to learn those different time schedules. They found that indeed
they could. So not only can they remember where the
food resources are, but they can keep track of multiple
variable schedules within their territory, like all in their head, right,
(26:11):
so they've got like a calendar in their head to
determine where like which, which resources have food, where are
they and when are they going to become profitable again?
And their brains are really really small, remember, because their
whole bodies are miniaturized, so their brains are much much
smaller than the brains of other birds. So it's really
(26:31):
quite incredible that they can do that.
Speaker 2 (26:33):
Yeah, I'm really impressed by their ability to map all
that out. And then I feel a little I can't
help but feel guilty by how like if I forget
to refill the feeder or to change out the nectar
and a feeder, I just now I'm going to feel
even worse because I'm messing with their finely tuned like
mental map of where all the flowers and the feeders are.
Speaker 3 (26:55):
Yeah, it is important if you're maintaining a Feeder's important
to keep it going. But you know they're they're really
resilient as well. They've been around for millions of years
before we started providing feeders. And uh, and so the
birds that are in your yard, they're in your neighborhood,
they're going to have other food sources mapped out. So yeah,
(27:19):
it's it's important, but it's unlikely to be catastrophic if
one person, you know, forgets to refill their feeder. But
what's also fascinating is that we're learning how those feeders
are changing are causing contemporary evolution in hummingbirds. The species
(27:41):
that we have on the east eastern North America here
Ruby tharted humming birds. Their populations are doing quite well
despite lots of threats that are that that humans are
creating for other bird species, and probably a big part
of that is humans providing food to them. On the
west coast, the Enna's hummingbird is a species that has
(28:03):
expanded its range, so it used to only live in
kind of warmer states in the southwest of the US,
and now we find that species and as humming bird
as far north as Vancouver, Canada, where we conducted our research.
They've expanded over the past century with people providing food,
(28:24):
both ornamental flowers but also feeders, and we're learning that.
There's a study that just came out this year. We're
learning how providing feeders is causing measurable changes to the
morphology of their beaks. Their beaks are changing in size
as they've been expanding. So it's really really neat because
(28:45):
beak shape evolution is kind of this classic case where
that led Darwin to come to appreciate how natural selection works,
and we humans are now causing that to happen on
rapid timescale.
Speaker 2 (29:02):
Wow, so what sort of changes are taking place here?
Are the beaks getting shorter longer?
Speaker 3 (29:08):
Yeah, so their beaks are getting longer to be able
to extract food from feeders and their way. Researchers have
been able to discover that is by measuring the beaks
of museum specimens that were collected over the past century
and kind of building up a time series of specimens
from you know, one hundred years ago, fifty years ago
to present.
Speaker 2 (29:29):
Wow, that's impressive. So you're spending all this time studying hummingbirds,
do they retain their magic for you or do they
become like just a little every day? Are they still exciting?
Speaker 3 (29:41):
They are still exciting. One of my favorite moments from
going out into the field at the sites where we
find our hummingbirds is getting to see courtship displays. Getting
to see a male court a female and we throw
a hummingbirds say do the shuttle display where they're zooming
back and forth and they start, you know, with a
(30:02):
small arc and they're flaring their colorful feathers in front
of the female and their shuttle gets bigger and bigger,
faster and faster. It's still really magical, even after handling
lots of hummingbirds in the lab. And the other thing
I find really exciting about them is seeing their behavior
slowed down. When if you capture interactions with high speed
(30:26):
video and then watch them at slow speed, it really
looks like you get an even greater appreciation for what
they can do because it looks like they're swimming in
the air. You know, it looks like like they're moving
in the air as definitely as we do kind of
on the ground, and you get a real impression for
(30:48):
things that they can do that you know, they just
whiz by you when you're seeing it in real life,
but there's a lot happening there.
Speaker 2 (30:55):
Yeah, I know just from this was several years back,
but I went with my family to Costa Rica and
we got to see some hummingbirds there at some feeders,
and just with whatever sort of iPhone we had at
the time, you know, you could take to take pretty
decent video and slow it down and gets this enhanced
appreciation for what they were doing. And so I can
(31:16):
only imagine what's possible a with today's iPhones and smartphones
and with like serious of film film equipment.
Speaker 3 (31:26):
Yeah, yeah, that's right. And Costa Rica has like a
huge diversity of species, and different locations that you'll visit
will have different species. And that's another question that continues
to fascinate me. The smallest hummingbirds we have are just
you know, two grams, which is the mass of a penny.
Speaker 2 (31:46):
Wow.
Speaker 3 (31:46):
And then the largest species we have is twenty grams.
That's ten times bigger. And then we've got three hundred
and sixty six species that span that range. Most of
them kind of between the two to ten size, which
is still a big range. Why is it that there's
so many different ways to be a hummingbird? How do
all of these like this one kind of overall strategy,
(32:09):
How does it lead to this diversification? And how do
they all coexist? Is another really fascinating question.
Speaker 2 (32:16):
All right, well, Roslin, thanks for coming on the show
and chatting with me today about hummingbirds.
Speaker 3 (32:20):
Thank you very much.
Speaker 2 (32:24):
Thanks once again to Rosalind Dacon for taking time out
of her day to chat with me again. The paper
is turning trade offs hummingbird power reserves are used to
decrease turning radius or increase turning velocity out now in
the Journal of Zoology, and you can learn more about
her work with the Dynamic Behavior Lab by visiting our
website at Rosalindacin dot com. This's r O s l
(32:48):
y N DA ki N dot com. Just a reminder
to everyone out there, The Stuff to Blow Your Mind
is primarily a science and culture podcast with core episodes
on Tuesdays and Thursdays, but on Fridays we set aside
most serious concerns to just talk about a weird film
on Weird House Cinema. Thanks as always to the excellent
JJ Possway for producing the show, and if you would
(33:09):
like to reach out to us, you can email us
at contact at stuff to Blow your Mind dot com.
Speaker 1 (33:22):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you're listening to your favorite shows.
Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. Robert Lamb.
Here in today's episode, I'm going to be chatting with
Rosalind Dakin, Associate professor at Carlton University in Ottawa and
principal investigator at the Dynamic Behavior Lab. We're going to
be chatting about hummingbirds, as she and her co authors
just had a new paper published in the Journal of
(00:33):
Zoology Turning trade offs. Hummingbird power reserves are used to
decrease turning radius or increase turning velocity. So, without further ado,
let's jump right into the interview. Hi, Rosalind, Welcome to
the show.
Speaker 3 (00:49):
Hi, thanks for having me.
Speaker 2 (00:51):
So we're going to be talking about hummingbirds today. We're
already really enjoying the company of hummingbirds down here in Atlanta.
Have they arrived up there where you are? Yeah, you're
in Ontario?
Speaker 3 (01:02):
Correct, Yes, exactly, I'm in Ottawa, Ontario. And they arrive
the first week of May the ruby started. Hummingbirds show
up almost like clockwork every year.
Speaker 2 (01:11):
It's always a joyous occasion here at my house when
we finally see the first humming birds of the season
appear at our feeders and flowers, and I think, you know,
at first it's the magic of them being here, the
way they move and all, But as you begin to
observe them, you really begin to notice how intensely territorial
they are about their flowers or about the cute little
(01:31):
feeder we've put out for them. Can you tell us, like,
why are they so territorial about this? Sometimes as humans
putting out feeders, we want to tell them like, no, no,
there's plenty you can share, and they're generally not having
any of that.
Speaker 3 (01:45):
Yeah, that's right. They have super competitive behaviors, and that's
something that we've been studying in my lab. Why they're
like that, I think it all comes down to their
super high metabolic rates. Their lifestyle relies on having a
steady stream of calories throughout the day, and if they
(02:06):
go even an hour without feeding, depending on how much
energy fat store they have in their body, that can
be death an hour without a meal. So those food
sources are really really valuable to them, and their metabolic
rates are so high. If you could scale a hummingbird's
body up to the size of the average adult human,
(02:26):
it would be like if you or I had to
eat one hundred and fifty large pizzas in a day.
Speaker 2 (02:32):
Wow, Now how can their wings that move so fast
to repel thems of the air.
Speaker 3 (02:37):
Yeah, so in order to be able to hover, hummingbirds
have to beat their wings, depending on the species, between
thirty to eighty times per second. So if you think
about a full wing stroke, that's your arm being fully
extended back, coming forward, and then back again and repeating
(02:58):
that cycle. For species like ruby throated hummingbirds, fifty times
every second. It's incredibly fast. So they have so that's
why they have such high metabolic rates, the highest of
any vertebrate animal per unit body mass. But they have
a lot of anatomical adaptations that are required to be
(03:19):
able to do that. So for example, they're pectoral muscles
that draw the wings down that activate the downstroke are
hypercha feed. They're really really large. But similarly, they have
another muscle, the super corecoidous muscle that draws the wing
back up, and it's also hypercha feed. It's also extra large.
(03:41):
In hummingbirds, they have skeletal adaptations as well, so the
muscle that the bones that those muscles attached to have
to be larger and more robust than they are in
other birds that have more typical wing beat frequencies, and
they also have dramatically modified and that so the bones
of their wing, these are the bones that we can't see.
(04:03):
We just see the feathered part of the wing, but
inside the hummingbird's wing they're humorous is really really short.
It's so short, it's almost like a little dot, you know,
It's just a couple of millimeters in length. And their
their wing is mostly hand And what that does is
it means that the heavy parts of their arm bones
(04:25):
are drawn in close to the body to make it
easier to beat those wings so fast. But it also
means that those muscles that are activating those wingstrokes are
working over a shorter distance, and so that makes it
physically possible for them to beat their ways at this
incredibly high frequency.
Speaker 2 (04:41):
So what evolutionarily has driven this development this arm's race
of hummingbirds. Is it just their diet and how they
need to feed it, is it predators, is it other hummingbirds? Like,
how does it all come together?
Speaker 3 (04:54):
Yeah, that's a super interesting question and one that we
have hypotheses, but it's still an active area of research.
If we go back, well, let's start with looking at
what we have today. The hummingbird family is extraordinarily diverse.
There's three hundred and sixty six different species and they
(05:17):
live in the Americas, so South America, Central America, the Caribbean,
and subspecies here in North America. That's incredibly diverse, and
they've radiated, they've diversified into all of these species over
the past twenty five million years. And if we look
at their closest relatives in the evolutionary tree, the family
tree of all birds, those are swifts, which are also
(05:40):
super agile birds. They're distributed across the globe. We have
swifts in North America. We also have swifts in Europe
and Asia that are aerial insectivores. So swifts spend almost
all of their time in the air catching flying insects,
so they have to be like little fighter pilots to
(06:01):
be able to chase down their prey. So the first
hummingbirds evolved around thirty million years ago from an ancestor
that was a really really acrobatic predator in the air,
and swifts have some of the same skeletal adaptations that
we see in hummingbirds. They have an enlarged keel. That's
the part of the bone on the breastbone where those
pectoral muscles attach, and swifts also have changes in their
(06:26):
wingbones that we see in hummingbirds as well, So that's
part of how we know where the hummingbirds fit in anatomically,
but also genetic studies have established what those relationships are.
So yeah, the first hummingbird was something something like an
insective war chasing down insects, and somehow, you know, maybe
(06:46):
they started to prefer insects that were associated with flowers,
and maybe that led to them consuming some nectar. We
don't know exactly what happened to produce this fift towards
being so specialized on flower nectar. But the other mysterious
part is that the earliest ancestor, the earliest fossil ancestor
(07:08):
we have of hummingbirds is not at all in the
same part of the world where we have all of
the species that we can observe today. The closest fossil
ancestor of hummingbirds they come from Europe, so fossils with
a lot of those hummingbird typical features, a long bill,
an exaggerated keel, and different wing proportions. Those have been
(07:31):
found in Poland and in France and multiple places, so
they arose in Europe we think, and at some point
made their way over to the Americas thirty twenty five
million years ago and from there diversified into very many
species day and a lot of that is the diversification
is probably due to specializing into different areas in the
(07:56):
Americas and in the Caribbean.
Speaker 2 (07:58):
So they're enhanced maneuver built in their power reserves, which
we're going to get into when we start talking about
your study here. This is largely for inter hummingbird competition
or do they have aerial predators they need to worry
about as well?
Speaker 3 (08:14):
They may have some effective predators. That's not something that
we observe very often, but we see a lot of
competition both between species and also within species, so especially
among males within a species, competing for a territory, competing
for a food resource. The other area where we see
them using their acrobatic skills is when they're courting mates.
(08:38):
So in very many species, the males will try to
impress females by doing an elaborate display in the air,
and the way that display goes will differ in different species,
but often they're zooming back and forth, reaching really high
speeds and turning quickly as part of that display, all
at the same time as they show the female their
(09:00):
colorful plumage and sometimes like make certain sounds while they're
doing those as place as well.
Speaker 2 (09:13):
So getting into your research a bit more here, tell
us a little bit about the Dynamic by Behavior lab
and how hummingbirds factor into your work there.
Speaker 3 (09:22):
Yeah, so we are interested in differences between individuals and
differences between species and when performance is such an important
part of how they survive, how is it that, like
what determines which individuals are dominant over which others, who's
winning those competitions, what traits determine who wins, But also
(09:45):
for individuals that are subordinate, what options do they have?
How do the subdominant individuals make a living? Those are
some of the questions we're studying in my lab. So
we measure things like they're an individual bird's ability to
generate power in flight, and we also measure their behavior
in big arenas where we can pit multiple birds against
(10:07):
each other competing over a food resource and seeing both
who's dominant, but also how are they using flight maneuvers
to outdo each other.
Speaker 2 (10:17):
Now, how do you go about studying something like this,
because hummingbirds, i imagine, are not easy creatures to study anyway,
and then you're dealing with some difficult to measure properties here.
Speaker 3 (10:26):
Right, Yeah, it takes a lot of patience. And one
of the nicest assays that's possible to do with hummingbirds
is a load lifting assay where we can measure the
maximum power they're able to generate with their flight apparatus,
with those muscles that are activating the wings. And we
do that assay in a chamber that's think of like
(10:50):
a vertical cylinder with kind of an open bright light
at the top, and a humming bird at the bottom
of that chamber is going to be highly motivated to
upwards try to escape, and we use an assay that
was developed decades ago by other scientists where we put
a little ring around the bird's neck that's attached to
(11:13):
a string of beads, and when we know the weight
of the beads along that chain, we can record what's
happening when the hummingbird gets released from the bottom of
the chamber. And if everything is set up suitably for
the bird as they try to escape upward with everything
they've got, we're able to measure exactly how many weights
or how many exact weight of the beads on that
(11:33):
chain that they're able to lift. The higher they go,
they're lifting more and more weight until they hit a
maximum and return back to the bottom of the chamber.
So we're able to develop an assay that just fits
with their capabilities their motivations to measure their maximum weightlifting ability.
Speaker 2 (11:52):
So essentially the tiny necklaces on hummingbirds is a part
of the study exactly.
Speaker 1 (11:57):
Yeah.
Speaker 3 (11:58):
Yeah, so we have to make those necklaces. Yeah.
Speaker 2 (12:00):
Wow. So this this latest study published in the Journal
of Zoology, really gets into their their maneuverability and their
power reserves. Can you lay out how these these two
aspects are linked. As I was reading the paper, I can't.
I really kept thinking of hummingbirds in like video game
terms and imagining like little meters at the top of
the screen.
Speaker 3 (12:19):
Yeah. So a couple of questions motivated this study, and
it was led by my colleague Paulo Segre and my
co author Doug Altuler. So one of the questions was,
when we're measuring their maneuvering performance, which includes lots of
complex behaviors that have a lot of degrees of freedom.
(12:42):
How tightly can they turn, how fast can they move
when they're turning, How fast can they accelerate decelerate? When
we're measuring those maneuvers, it's really hard to capture what
is a bird's maximum ability? The more freedom you give
them in a space where you're capturing what they do,
the less well defined maximum is because there's so many
(13:03):
different ways to move in a completely open environment. So
we've been studying maneuvering ability in across the different hummingbird
species for some years, but we wanted to know is
the power they're able to generate in a more constrained
assay like our low lifting assay, is it predictive of
(13:24):
some maximum that we're able to capture in this free
flight assay. That was the motivation for that study, so
led by Pollow. What Pollo did was he reasoned using
fundamental physics that one of the basic maneuvers that they
use very frequently to turn, which we're calling an arcing urn,
which is basically just a level turn that if you
(13:47):
look at it from above, you follows a smooth arc.
He reasoned that those arcing terns that we can build
a physical model of the forces that they need to
to produce those arcing turns, and we can test whether
(14:07):
the maximum load that a bird is able to lift
in our low lifting assay does that correspond with the
maximum that they're hitting up against as they redirect forces
during those arcing turns.
Speaker 2 (14:21):
So one of these arcing terns you're describing here, would
this perhaps be one of these maneuvers we see when
one hummingbird chases another hummingbird away from a feed or
flowers in our yard.
Speaker 3 (14:33):
Yes, absolutely, yeah, and yeah, definitely they'll use arcing urns
during chases. They'll also use arcing turns during obstacle avoidance,
which is really important to a fast moving animal. Those
collisions could be deadly.
Speaker 2 (14:48):
Yeah, these the collision avoidance turns. I guess I don't
notice as much because if they're avoiding collision with my head,
it's all happening so quickly. But yeah, but sometimes we'll
be watching them off, and we'll be watching them and
we'll see one chase the other off, and it sounds
like that's what you're talking about here.
Speaker 3 (15:05):
Yeah, exactly.
Speaker 2 (15:06):
Yeah, I'm sorry, but I got us off topic here.
You were describing your analysis of these turns.
Speaker 3 (15:13):
Right, Yeah, So in those free flight essays, we aren't
telling the birds what to do. They're performing at a
sort of routine flight level of performance as they're trying
to avoid the threatening experimenters avoid collisions with the size
of the flight chamber. But we can capture thousands of
(15:34):
maneuvers from each individual over a relatively short span of
time because everything hummingbirds do just happens on much faster
timescale than other species or than their own lives. So
if you record a hummingbird for two hours, you might
capture two thousand arcing turns, for example. And so we
can computationally pull out the segments of flight that represent
(15:56):
the arcing turns that we're limited to a level plane,
and we can apply the physical model that Paolo built
to say, okay, the redirection of forces as the bird
is banking its body to execute that turn, what's the
what's the kind of space of what that looks like
(16:17):
for the many, many thousands of turns that we captured
from the different humming birds in our study. We studied
about twenty individual hummingbirds in that study. And does the
does the limit of that, but distribution, how does that
align with our predicted limit from how much weight those
birds could lift in our highly constrained load lifting assay,
(16:41):
And what we found was that overall, collectively, the model
predicts really well the maximum turning performance of the birds
in that chamber. So the Anna's hummingbirds that we study
either from the west coast of North America slightly larger
species than we have here in Ottawa or where you are,
(17:05):
but they have in our little lifting I say they
can lift about two and a half times their body
weight on average, and we can model what that would
translate to in terms of being able to redirect forces
to execute that turn. And the birds in our free
flight experiment, their peak performance matches that peak of what
(17:29):
we would predict based on their maximum ability. So it's
really satisfying. It It aligns with our hypothesis that in
order to be maneuverable, that power has to come from
their muscle capacity and flight and their kind of excess
muscle capacity. Their ability to just lift weights vertically is
going to determine how well they can execute these high
(17:53):
performance acrobatic maneuvers.
Speaker 2 (17:55):
So as they're flying about during the day, like how
often are they like at absolutely using up their powers.
Speaker 3 (18:02):
Yeah, that's a really good question that we don't know
the answer to yet. And how often are they hitting
their maximum out in nature? Probably not that often compared
to you know, when you think of like the lifespan
of a hummingbird and and how much they do during
it during the day, I would estimate, I would hypothesize
(18:23):
that it's it's pretty rare that they're executing maneuvers that
are that are hitting their max. But in our flight chamber,
you know, it was a pretty small proportion, maybe one
percent of the turns are kind of hitting that maximum envelope.
And and maybe it's similar out in the wild. But
that's something that we'll be able to test in the future,
(18:46):
for example, by having sensors small enough to put on
a really small bird. That's kind of the challenge there.
But a lot at the time of the like you know,
a lot of their time of the day they spend
perching and and probably one of the biggest challenges for
them is maintaining the muscle mass that they would need
(19:07):
to execute those rare super high performance maneuvers.
Speaker 2 (19:11):
That's absolutely fascinating. Now I have I have another question
or two about just studying the hummingbird, Like we as
we observe them, you know, we we obviously pick up
that they are they're very powerful creatures in their own right,
(19:33):
but we also get the sense of fragility about them.
Are they are they fragile to deal with?
Speaker 3 (19:38):
Like?
Speaker 2 (19:38):
What how is it different dealing with hummingbirds versus other
birds you might be studying in your in your work.
Speaker 3 (19:46):
Yeah, I would say in the lab there their relatives
are easy to deal with compared to other species. And
part of that might be they're they're so specialized. If
you kind of know the conditions they need, they're relatively
easy to keep healthy. The main point of fragility is
(20:08):
that's super high metabolic rate. If they run out of food,
that's catastrophic. But if you've got the right conditions for them,
kind of unlimited food, the right physical space, they're pretty
easy to deal with in the lab. But we have
to cows them separately, and that's different than other birds because, yeah,
they're so aggressive. They they would exclude each other from feeding,
(20:32):
for example, and their bills can be a weapon. So
when when they're kind of housed in captivity, we keep
each individual on its own and you don't see it
that often in the wild. But but if you have
video footage, high speed video footage of birds interacting and
(20:53):
fighting at a feeder, you'll see how that bill is
really like a long dagger, and that they're they're facing off,
they're making sure they orient their bills towards towards each other.
You can imagine a collision with those long bills would
be really catastrophic for an animal that only weighs two
and a half grams.
Speaker 2 (21:10):
Oh wow, Yeah, that was going to be one of
my questions, like what is the We see them chasing
each other, like, what are they actually doing to each other?
If they catch it, it's kind of it sounds like
it's like a joust in a sense, right, yeah.
Speaker 3 (21:23):
And it's really hard for us to capture what that like,
what are the consequences of that in the while the
best examples we have are footage that people can capture
at a feeder and when birds really get into it
close to a feeder, what happens and you see them
grabbing each other's feathers and using their bills to defend
(21:43):
that space to displace another bird. And and there's still
a lot of open research questions about you know exactly
how like what what signals or outcomes are determining who
wins those competitions and and that's an active area of
work that we're studying now in my lab. But even
(22:04):
in the lab, we'll see them rarely make physical contact
with each other. So if one bird wants to displace
another from a perch, sometimes they'll get into little scuffles
where they're making contact, and I think at high speeds
those kinds of scuffles would be really dangerous to both individuals.
So it's a real game of chicken.
Speaker 2 (22:25):
Now, when you're studying hummingbirds, is it completely seasonal? Is
it seasonal availability very much a part of this or
do you have hummingbirds like in captivity that you can
study year round.
Speaker 3 (22:36):
Yeah. So in my lab here in Oddwell, we're studying
ruby started hummingbirds and they are migratory and so we've
been catching birds here since the beginning of May, and
we've got a group of males in the lab now
that will release again prior to their autumn southward migration.
So we're only working with them within the breeding season
(22:57):
here and only studying the males, and remarkably many individuals,
many of the migratory species, an individual humming bird will
come back to the very same feeder. So one of
the birds in my lab now is a bird that
we caught and released on campus last year. Attached a
(23:18):
little band to his leg with an identifying number, and
he would have migrated all the way to Mexico, and
then this spring, the first two weeks of May, like clockwork,
he showed up at the exact same feeder. We captured
him again this year. So it really is remarkable not
only the physical feats that they do, but also they
(23:38):
have remarkable memories and that's all part of their high
metabolic rate. They need to know where those reliable food
sources are. So this male were bethowted humming bird came
back to the exact same feeder after this cross continental journey.
Speaker 2 (23:52):
That was going to be one of my follow up
questions about the what's going on in the mind of
a hummingbird, And it's because again, they just they're such
drastically different creatures. They're living on this time frame, you know,
that's so different from ours, and then vast distances in
addition to vast speeds, so we have what else do
we know about their about the way their little brains work.
Speaker 3 (24:15):
Yeah, it's really fascinating. So there's a lot of excellent
research coming out of my co author, Doug Altruler's lab
on how their brains work and how the visual system works.
And we also have studies of their spatial memory. And
so a really beautiful study from about twenty years ago
now on a species of hummingbird that lives in the
(24:37):
Rocky Mountains looked at their ability to learn flowers that
change in nectar availability through time. So real flowers are
not like feeders. Real flowers will be depleted and will
replenish themselves over some seasonal period. And hummingbirds that have
(25:02):
a territory with lots of flowers in them, they need
to know where their next meal is coming from, and
they're able to learn the locations of many flowers. As
an example, this bird that came all the way back
to my feeder from Mexico, he would have remembered other
places along that route, we hypothesize. So what the researchers
(25:26):
did in Alberta, Canada was create an experiment where they
could track one male in the wild who had a
territory and they had dynamic feeders in that territory that
went on different time schedules. Maybe some feeders would replenish
on five minute intervals, others on ten minute intervals, others
on twenty minute intervals. And if a bird had multiple
(25:49):
of those variable timed feeders available, would they be able
to learn those different time schedules. They found that indeed
they could. So not only can they remember where the
food resources are, but they can keep track of multiple
variable schedules within their territory, like all in their head, right,
(26:11):
so they've got like a calendar in their head to
determine where like which, which resources have food, where are
they and when are they going to become profitable again?
And their brains are really really small, remember, because their
whole bodies are miniaturized, so their brains are much much
smaller than the brains of other birds. So it's really
(26:31):
quite incredible that they can do that.
Speaker 2 (26:33):
Yeah, I'm really impressed by their ability to map all
that out. And then I feel a little I can't
help but feel guilty by how like if I forget
to refill the feeder or to change out the nectar
and a feeder, I just now I'm going to feel
even worse because I'm messing with their finely tuned like
mental map of where all the flowers and the feeders are.
Speaker 3 (26:55):
Yeah, it is important if you're maintaining a Feeder's important
to keep it going. But you know they're they're really
resilient as well. They've been around for millions of years
before we started providing feeders. And uh, and so the
birds that are in your yard, they're in your neighborhood,
they're going to have other food sources mapped out. So yeah,
(27:19):
it's it's important, but it's unlikely to be catastrophic if
one person, you know, forgets to refill their feeder. But
what's also fascinating is that we're learning how those feeders
are changing are causing contemporary evolution in hummingbirds. The species
(27:41):
that we have on the east eastern North America here
Ruby tharted humming birds. Their populations are doing quite well
despite lots of threats that are that that humans are
creating for other bird species, and probably a big part
of that is humans providing food to them. On the
west coast, the Enna's hummingbird is a species that has
(28:03):
expanded its range, so it used to only live in
kind of warmer states in the southwest of the US,
and now we find that species and as humming bird
as far north as Vancouver, Canada, where we conducted our research.
They've expanded over the past century with people providing food,
(28:24):
both ornamental flowers but also feeders, and we're learning that.
There's a study that just came out this year. We're
learning how providing feeders is causing measurable changes to the
morphology of their beaks. Their beaks are changing in size
as they've been expanding. So it's really really neat because
(28:45):
beak shape evolution is kind of this classic case where
that led Darwin to come to appreciate how natural selection works,
and we humans are now causing that to happen on
rapid timescale.
Speaker 2 (29:02):
Wow, so what sort of changes are taking place here?
Are the beaks getting shorter longer?
Speaker 3 (29:08):
Yeah, so their beaks are getting longer to be able
to extract food from feeders and their way. Researchers have
been able to discover that is by measuring the beaks
of museum specimens that were collected over the past century
and kind of building up a time series of specimens
from you know, one hundred years ago, fifty years ago
to present.
Speaker 2 (29:29):
Wow, that's impressive. So you're spending all this time studying hummingbirds,
do they retain their magic for you or do they
become like just a little every day? Are they still exciting?
Speaker 3 (29:41):
They are still exciting. One of my favorite moments from
going out into the field at the sites where we
find our hummingbirds is getting to see courtship displays. Getting
to see a male court a female and we throw
a hummingbirds say do the shuttle display where they're zooming
back and forth and they start, you know, with a
(30:02):
small arc and they're flaring their colorful feathers in front
of the female and their shuttle gets bigger and bigger,
faster and faster. It's still really magical, even after handling
lots of hummingbirds in the lab. And the other thing
I find really exciting about them is seeing their behavior
slowed down. When if you capture interactions with high speed
(30:26):
video and then watch them at slow speed, it really
looks like you get an even greater appreciation for what
they can do because it looks like they're swimming in
the air. You know, it looks like like they're moving
in the air as definitely as we do kind of
on the ground, and you get a real impression for
(30:48):
things that they can do that you know, they just
whiz by you when you're seeing it in real life,
but there's a lot happening there.
Speaker 2 (30:55):
Yeah, I know just from this was several years back,
but I went with my family to Costa Rica and
we got to see some hummingbirds there at some feeders,
and just with whatever sort of iPhone we had at
the time, you know, you could take to take pretty
decent video and slow it down and gets this enhanced
appreciation for what they were doing. And so I can
(31:16):
only imagine what's possible a with today's iPhones and smartphones
and with like serious of film film equipment.
Speaker 3 (31:26):
Yeah, yeah, that's right. And Costa Rica has like a
huge diversity of species, and different locations that you'll visit
will have different species. And that's another question that continues
to fascinate me. The smallest hummingbirds we have are just
you know, two grams, which is the mass of a penny.
Speaker 2 (31:46):
Wow.
Speaker 3 (31:46):
And then the largest species we have is twenty grams.
That's ten times bigger. And then we've got three hundred
and sixty six species that span that range. Most of
them kind of between the two to ten size, which
is still a big range. Why is it that there's
so many different ways to be a hummingbird? How do
all of these like this one kind of overall strategy,
(32:09):
How does it lead to this diversification? And how do
they all coexist? Is another really fascinating question.
Speaker 2 (32:16):
All right, well, Roslin, thanks for coming on the show
and chatting with me today about hummingbirds.
Speaker 3 (32:20):
Thank you very much.
Speaker 2 (32:24):
Thanks once again to Rosalind Dacon for taking time out
of her day to chat with me again. The paper
is turning trade offs hummingbird power reserves are used to
decrease turning radius or increase turning velocity out now in
the Journal of Zoology, and you can learn more about
her work with the Dynamic Behavior Lab by visiting our
website at Rosalindacin dot com. This's r O s l
(32:48):
y N DA ki N dot com. Just a reminder
to everyone out there, The Stuff to Blow Your Mind
is primarily a science and culture podcast with core episodes
on Tuesdays and Thursdays, but on Fridays we set aside
most serious concerns to just talk about a weird film
on Weird House Cinema. Thanks as always to the excellent
JJ Possway for producing the show, and if you would
(33:09):
like to reach out to us, you can email us
at contact at stuff to Blow your Mind dot com.
Speaker 1 (33:22):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you're listening to your favorite shows.
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