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Nikita Chernetsov on Magnetic maps in migratory birds — Transcript

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0:17Thank you. Thank you, Henrik. So, uh now
0:19we are going to talk about uh
0:22magnetic maps in migratory birds, but
0:25before we do that, I want to say just a
0:28couple of words
0:30about bird migration in general. I don't
0:33need to say much because Henrik has done
0:35it for me already, and he has already
0:38shown these
0:40Does it work?
0:41I mean, anyway, I can show it
0:43physically. I mean, uh
0:45these pattern of of northern wheatears
0:48migrating from Alaska
0:51uh to uh northeastern Africa, and I also
0:55wanted to show
0:57uh
0:58these satellite tracks of godwits that
1:01migrate from Alaska to New Zealand
1:03nonstop. I mean, these are actual
1:05satellite tracks
1:07of birds going
1:09nearly 11,000 km across the Pacific
1:13nonstop without a possibility to uh land
1:17and to rest. It's a feat in endurance
1:21flight. It's very interesting how they
1:23cope with sleep deprivation, and
1:25certainly it's
1:27a very important navigation challenge
1:30because if you make a small mistake and
1:33miss New Zealand,
1:35then evolution will continue without
1:37you.
1:39And uh
1:42uh this is just to show you that birds
1:44perform
1:45incredible things. Did they get that on
1:47the satellite track? Sorry? How long is
1:49that journey? 8 to 9 days. Right.
1:52Nonstop flight.
1:55Without proper sleep, maybe with
1:57hemispheric uh sleeping in one
1:59hemisphere, but we don't know that.
2:02Uh and we have talked yesterday, we have
2:05discussed yesterday what is a compass
2:08and what is a map. And I would like to
2:11emphasize that there is an This is an
2:14important distinction because
2:16any animal, not just a bird, any animal
2:19that moves far beyond its normal home
2:22range,
2:23and
2:24if it wants to get to a any specific
2:27place, it should have
2:29a map or
2:32some representation, some mental
2:34representation of space.
2:36Eric emphasized yesterday that it does
2:39not need to be identical to our
2:41representation in topographical maps,
2:44but
2:46there should be some some kind of
2:49representation of space.
2:51And
2:53also a compass system, which
2:55makes it possible to select and maintain
2:58a direction.
3:00And Henrik has spoken quite a lot about
3:04compass systems, and this distinction
3:07was I mean, the conceptual frame was
3:09provided by Gustav Kramer, whom Henrik
3:12has already mentioned. And I am These
3:14are the only two references that I
3:17really spell out in my in my
3:19presentation out of respect to Gustav
3:23Kramer, because this was a very
3:25important thing. A map and a compass,
3:28they An animal needs both, and they do
3:32not need to be identical in the sense of
3:36physical and sensory background.
3:39For migrating birds, most
3:42most students agree that birds have a
3:45sun compass, a stellar compass, and a
3:47geomagnetic compass, as we have heard
3:49from Henrik.
3:51And uh,
3:53there is less of agreement, but many
3:56people think that birds can use a
3:58magnetic positioning system or a system
4:01or map, and olfactory map, and well,
4:04about others I'm not so sure.
4:07Uh, but, uh, it is not impossible that a
4:12bird or any other animal uses, say, an
4:16olfactory map and a magnetic compass or
4:19a
4:21uh, star compass and magnetic map at the
4:23same time. So, these two systems are
4:26certainly have to work in concert, but
4:29they do not need to be identical in
4:32their physical and, uh, sensory sense.
4:36And that's why the question how do
4:38migrating animals find their way, which
4:40was uh, listed by Science Journal not so
4:44long ago as one of the most important,
4:46well,
4:47one of 125 most important unanswered
4:51questions of of current natural
4:53sciences, this question actually
4:55consisted consists of two
4:58related but distinct questions. What is
5:01the nature of the compass, and what is
5:03the nature of the map? And I'm going to
5:06speak
5:07about the nature of maps or positioning
5:09systems in birds,
5:11and as I already mentioned, uh,
5:15there are two,
5:17I would say, less exotic
5:20uh, ideas how they do it, and I'm going
5:23to speak about the magnetic maps of
5:26migrating birds, and Anna Gagliardo is
5:29going to present, uh, the olfactory
5:31component. And, yes. But before you
5:34continue, just a few on your list, you
5:36don't have the We just discussed at the
5:38end of Henrik's talk that the, right,
5:40the birds
5:41uh, migrate, and they have this coarse
5:43map that's not a magnetic,
5:45and it made the point yesterday the
5:46magnetic map cannot be more precise than
5:49a few tens of kilometers.
5:50That's true. Theoretically. Then to
5:52pinpoint the particular tree then they
5:54must have also a visual based landmark
5:56map which is
5:58Yes.
5:59You're You're You're right. I'm speaking
6:01now of large-scale maps uh for for
6:05large-scale navigation. They certainly
6:09certainly
6:10uh
6:10birds cannot pinpoint cannot perform
6:14pinpoint navigation that we know they
6:16are capable of pinpoint of performing
6:19without uh recognizing visual patterns,
6:23landmarks, not necessarily visual
6:25landmarks. They might use also uh other
6:28sensory landmarks.
6:30Uh but uh uh
6:33as long as we are speaking of navigation
6:36across
6:37hundreds and thousands of kilometers, I
6:40mean global global navigational on
6:42global scale. And as we have uh
6:45mentioned that it doesn't need to be
6:48truly global. I mean uh
6:50chiffchaff or chiffchaff finch uh breed
6:54that breeds and winters within Europe
6:56may survive without being able to
6:58navigate in South America. It's not
7:01impossible for such a bird. But across
7:04the range
7:05uh of the particular population and
7:07maybe slightly beyond for the case it is
7:10it is displaced.
7:12Uh and uh
7:13I'm going now to present the
7:16uh available data that suggests that at
7:20least some songbirds do use the magnetic
7:23map.
7:25Uh but at first I'd like to say a couple
7:27of words about the methods. Henrik
7:29already mentioned them. Uh Emlen funnels
7:32and uh
7:34the fact that we have that we bird
7:37people
7:38have the ability
7:41they have a chance to take our birds
7:43into the lab and test them their
7:46orientation preference under the
7:47controlled conditions is the reason why
7:51we know much more about avian navigation
7:55and orientation mechanisms
7:57than about orientation navigation
7:59mechanism of other animals who also
8:02migrate but it is
8:04more than just one bit challenging
8:07to put a whale or a shark into an
8:09equivalent of an Emlen funnel and that's
8:11why we don't know much about them and
8:15and bats they do not they are not active
8:19in round arenas during their migration
8:21they're smart enough to realize that
8:24they are not moving anywhere
8:26that's why we cannot test bats in a
8:29similar situation and that's why we know
8:32less about their orientation mechanism
8:34and cues they're using.
8:36And Henrik has already
8:38emphasized how a noisy Emlen funnel data
8:42are and for
8:44uh
8:45uh for a comparison I have the data of
8:48free-flying
8:50uh
8:50radio-tagged free-flying
8:53uh song thrushes and you can see
8:55free-flying birds that were not induced
8:58to take off but just took off with
9:02uh
9:03with radio tags but they took off on
9:05their own you see how how concentrated
9:08their directions their vanishing
9:11directions are. So
9:13uh in in the wild they do something like
9:16this
9:17and uh
9:19in the cage they do something like this
9:21and this is certainly a problem because
9:23you need to
9:25do uh to perform many tests and your
9:29expected expected angles should be
9:33different enough because if you have
9:35if you have an expected difference of 30
9:38degrees you'll be probably you'll
9:40probably be never able to detect the
9:43existing difference just because of the
9:46method you are using.
9:48And then I just wanted to show you how
9:50what the birds really do in the
9:53in Emlen funnels, how it looks like in
9:56reality.
9:58It promises me the computer promises me
10:01that it's going to
10:06Aha.
10:12Can you see anything?
10:14Yes. Yes, this is this is what what a
10:17bird really does.
10:18Uh it is a
10:20uh video tape and then you can use the
10:23traditional funnels or you can use
10:25analyze these video tapes. It's up to
10:27you. And if you need a
10:30temporal resolution, then you may want
10:32to use videos. If you don't need it
10:35really, you can use uh old school Emlen
10:39funnels without video.
10:41And this is And now I'm going to talk
10:44about the
10:45geomagnetic field and how it
10:48is or may be used for long-distance
10:50navigation for long-distance maps. You
10:53have seen this
10:54picture already and uh I'm not going to
10:57explain it in any any much detail. I
11:00just want to emphasize that there are
11:02two
11:04uh most important primary features of
11:07the magnetic field.
11:08It is the inclination angle, which
11:11differs which varies. So, inclination is
11:14the angle between the
11:16magnetic inclination is the angle
11:18between the field lines and the
11:19horizontal plane. It's by It's 90
11:23degrees at magnetic poles and zero at
11:26the magnetic equator. And this is the
11:28definition of the magnetic equator,
11:30which does not coincide exactly with the
11:33geographical equator,
11:35just like the magnetic poles are not
11:37exactly located at geographical poles.
11:40And uh
11:42you can see how it varies. These are the
11:44iso lines of the of magnetic
11:46inclination, and you can see that even
11:49though there are some
11:51irregularities, but generally these iso
11:55lines run very close to
11:59parallel to geographic parallels.
12:02So uh it So these uh parameters are
12:04theoretically, if you can measure it,
12:07can give you the north-south axis.
12:10And then uh another important parameter
12:14is the total intensity of the
12:15geomagnetic field.
12:17It's uh roughly it's also some
12:20variation, but roughly it's the field is
12:23twice as strong uh near magnetic poles
12:26as uh on the magnetic equator.
12:29And then this is how these li- these
12:32parameters arise. And you can see that
12:34in some areas it is more more or less
12:37parallel to geographic parallels and to
12:41uh iso lines of inclination, and in some
12:44areas
12:47it
12:48runs
12:49uh along the north-south axis. And uh
12:52then it forms a nice grid. I mean, the
12:54grid that Eric showed us yesterday in
12:57the southern Indian Ocean, it was a very
12:59nice special case.
13:03It is really nice special case. I mean,
13:06uh seabirds that have to navigate
13:08southern Indian Ocean, they are in a
13:10very privileged position because they
13:12really have a a b-coordinate grid
13:16close to be to close to be really
13:19perpendicular.
13:21Uh but I mean, it's not like this
13:24everywhere on Earth.
13:26Say in
13:27uh if you superimpose these isolines,
13:31you can see that in some areas, it's
13:34fine.
13:35In some areas, these lines uh run
13:38parallel
13:39to each other and do not form a grid.
13:43And in some areas, they line uh they
13:45they run under an angle which is not
13:48zero, but not 90° either.
13:51And uh our Swedish colleagues from Lund,
13:55they made a very nice analysis. They
13:57just
13:58uh looked uh
14:01at uh at uh the angles under which the
14:04isolines intersect.
14:06And they assumed, it is just a guess,
14:09but I think it's it's a fair guess that
14:12uh when the isolines intersect at
14:15degrees exceeding 30°, it can be used
14:18for
14:19B coordinate navigation. Certainly, 90°
14:22is perfect. It's Cartesian coordinates,
14:25but it doesn't need to be Cartesian
14:27uh 90°.
14:29And uh so these uh areas are shaded uh
14:32green in this map. Yellowish are the
14:35areas where the angle is between 3 and
14:3830°.
14:39So, it is
14:40more or less okay.
14:42And red
14:44areas are where um
14:47uh where these uh the angle between the
14:50isolines is less than 3° and where it is
14:53really very very challenging
14:56to use uh a purely magnetic map
15:00uh
15:01for B coordinate navigation. So, you see
15:04that
15:05fairly large numbers of our planet are
15:08shaded green.
15:09Many areas are yellowish, where it is
15:12maybe possible,
15:14but birds migrate also in the areas
15:17which are red. So, they somehow find a
15:20solution, and we'll talk about this
15:22solution later on or what solution it
15:26might be based on the magnetic
15:28properties.
15:30Uh, but this is just for you to have an
15:33idea where the magnetic map can be used
15:36for long-range navigation and where
15:39purely magnetic map and where it would
15:41be a challenge.
15:43And now we need to say a couple of words
15:46about how birds uh a couple of words
15:48about how birds perceive the magnetic
15:50field. Henrik is going to talk quite a
15:53lot about the
15:55uh
15:57uh about the molecular market mechanisms
16:00that underlie
16:01uh magnetoreception. I'm now I'm I'm now
16:05uh going to say only very basic things.
16:08And it is believed that birds have two
16:12different separate magnetoreceptor
16:14systems.
16:15This is This was very unexpected, but it
16:19seems that birds have two systems that
16:22are based uh on different physical
16:25principles
16:26and that uh are
16:29uh locate and they that are innovated by
16:33different nerves
16:34and processed in different parts of
16:36their brains.
16:38And uh a lot of research is being done
16:41about concerning uh
16:44the system which is believed to be based
16:48on vision
16:49and is believed to be based physically
16:52on uh uh
16:55light-dependent chemical reactions
16:58that probably
17:00occur in avian retina.
17:03And uh
17:05this is uh
17:07known I mean this uh vision-based
17:10magnetic sense that the birds have
17:14is believed uh to be used for the
17:16magnetic compass.
17:18And Henrik will talk about it a lot.
17:21Uh and I'm not going to talk about this
17:25magnetoreceptor system at all.
17:27And uh
17:29there is another magnetoreceptor system
17:33which
17:34people believed is located
17:36somewhere in uh birds' beaks, and
17:39probably it is, but we know less about
17:41it
17:42than we thought some time ago.
17:45And uh this uh
17:47magnetoreceptor system is believed to be
17:50based on uh iron particles on uh iron
17:54oxide particles.
17:56And it is believed uh
17:59it is believed to be It is definitely
18:01not necessary for the magnetic compass
18:04to operate. The magnetic compass as
18:07Henrik's uh Henrik with people from his
18:09lab was able to show the magnetic
18:12uh uh compass can operate without
18:14information from this system.
18:17And this system uh transmits information
18:20into the brain through the trigeminal
18:21nerve.
18:23And uh people think that uh this uh
18:26system, this magnetic information, might
18:28be used
18:30for mm for or for
18:32for
18:33magnetic positioning system, and I'll
18:34show you why people think so.
18:37So, uh
18:40some time ago,
18:42people thought that they found
18:45uh
18:45the receptor.
18:47Uh
18:49People colleagues from the University of
18:51Frankfurt, uh
18:52Gert and Günther Fleissner,
18:55uh
18:55assumed that they found iron-containing
18:58cells
18:59in uh the upper beaks of pigeons. And
19:03they believed that these cells were
19:05colocalized with neuronal markers.
19:09And they even made a
19:11mm
19:12produced a
19:14model of how a receptor could look like
19:17and it looked very nice. I mean, it
19:20really looked nice. Two receptors, this
19:23receptor innovated by the
19:26uh by the ophthalmic branch of the
19:31Not
19:32ophthalmic branch of the trigeminal
19:34nerve.
19:35Uh everything's fine.
19:37And then they were able this is a
19:40photograph of of
19:42a pigeon beak from below. They were able
19:45to find to they thought that they saw
19:48three
19:49uh
19:50three points.
19:52Uh I mean, six because three of each
19:54side and and they assumed that they were
19:57responsible for the three
19:59uh three dimensions. So, it looked like
20:03and then and then people thought made
20:06very nice uh
20:08ideas how how
20:11action potential could be generated.
20:13Some there were several models. I mean,
20:17uh
20:18They
20:19some model suggested that the magnetic
20:22field
20:23triggered movements of a super
20:25paramagnetic
20:27uh clusters and which induced
20:29deformation in the membrane and opening
20:31of ion channels and then thus generation
20:34of action potentials.
20:36Uh in some models these particles were
20:40physically connected to the membrane in
20:42others not and everything was very fine.
20:45But, it seems that this story was just
20:48too nice to be true.
20:50And people from
20:53uh Vienna
20:54were able to show that
20:5797% of these iron-containing cells in
21:01pigeon upper beaks
21:04were
21:05uh had nuclei
21:08which rules out these cells being
21:10dendrites.
21:12No way.
21:13And then they uh also were able to prove
21:18that at least 94 of these cells were
21:21macrophages, which are known to be uh to
21:25be depots for iron.
21:28And they were not localized in
21:31uh in specific clusters along the beak.
21:35And uh
21:37I mean, the story
21:39the story collapsed. And this is a
21:42picture from uh Hendrix review,
21:46which shows that
21:48that probably there are no six specific
21:50locations, but a diffuse distribution of
21:53these iron-containing cells.
21:55They probably have nuclei.
21:58They uh
22:01have ferritin-containing siderosomes and
22:03not magnetite
22:05uh
22:06spherules, so
22:08it seems we thought that we had the
22:10receptor.
22:12And it seems that we don't.
22:15And this is I mean, for hardcore sensory
22:17physiologists, it's really a no-no. When
22:20you cannot show the receptor,
22:22well,
22:24what are we talking about?
22:25However,
22:27uh it seems that uh it does not I mean,
22:30these results uh do not mean that there
22:33is no magnetoreceptor,
22:36which uh transmits in from transmits
22:38information into the brain through the
22:41trigeminal nerve.
22:43Because there are some behavioral data
22:46showing that uh
22:49pigeons
22:50could uh
22:51perceive could be trained in a
22:54uh
22:55uh
22:56could be trained to uh
22:58find food based on them on the presence
23:01or absence of a magnetic strong magnetic
23:04anomaly
23:05uh
23:07only if their trigeminal nerves were
23:11intact.
23:13I mean the pigeons could discriminate
23:15between
23:17uh between presence and or absence of
23:20the
23:21magnetic strong magnetic anomaly
23:24if they
23:25uh
23:26uh if they had their
23:29uh trigeminal nerves intact
23:32when they had their olfactory nerves
23:35sectioned but trigeminal nerves intact,
23:37they were still much better than chance.
23:40And if they when they had their
23:41trigeminal nerve sectioned they were
23:45down to the chance level. So, it seems
23:47that they in order to be able to
23:49discriminate
23:51uh the magnetic
23:52to to perceive the magnetic anomaly,
23:54they needed
23:55uh to have
23:57uh intact trigeminal nerves.
24:00And also
24:01it uh
24:04has been shown that
24:06uh
24:08by by Dominik Heyers from and other
24:11people from Henrik's lab uh it was shown
24:14that uh
24:16magnetic
24:17magnetic super stimulus I mean super
24:19stimulus is a very strong constantly
24:22changing magnetic field.
24:24Uh it caused activation in the
24:27trigeminal nuclei in the brain
24:30uh of European robins and uh it was
24:33shown by
24:35by the expression of uh
24:38uh early genes and uh which which
24:42indicates that this particular brain
24:44area is active. And when uh
24:47robins with intact
24:50uh trigeminal nerves were given
24:52uh strong magnetic super stimulus I mean
24:55strongly and chaotically changing
24:57magnetic field.
24:59They had uh
25:01above baseline activation, I mean,
25:03significantly above baseline activation
25:06in the
25:07uh nuclei of the trigeminal in the
25:09specific nuclei of
25:11uh
25:11that are innovated by the trigeminal
25:14nerve when the the same birds were in
25:17the zero magnetic field, true zero
25:19magnetic field, the activation was down
25:22to the baseline level. And when the
25:25trigeminal nerve was sectioned,
25:27they
25:28it was the same, it was down to the
25:30baseline level.
25:32So, it seems that uh
25:36uh magnetoreceptors, which we Yes,
25:39please. Sorry, yeah, just with the with
25:41the highest paper, were you saying that
25:43the magnetic levels they were using for
25:44testing were were very or much higher
25:47than kind of the natural
25:49Yes.
25:49levels of magnetism that you would find.
25:51Yeah. So, yeah. Not really.
25:54Uh okay.
25:55So,
25:56the
25:56the exact stimulus was 5 minutes of
26:00Earth's strength magnetic field that
26:02changed
26:03approximately 90° over 30 seconds.
26:07These were Earth's strength field where
26:08we intentionally did not
26:11correct for the small inaccuracy in the
26:13coil, so the intensities will have
26:15changed a few hundred nanotesla.
26:17So, that's like a very natural stimulus.
26:19Then, after that, we had 5 minutes
26:22of the magnetic field on the three axes
26:24changing from zero to 70,000 nanotesla
26:27on each axis randomly.
26:30And this results in field between almost
26:32zero in some cases up to 140
26:35uh thousand nanotesla. So, that's
26:38basically uh very strongly changing in
26:40all parameters, and that switched every
26:425 minutes, we switched those two
26:44stimulus with new randomization.
26:46And the thinking behind that stimulus is
26:48that maybe birds
26:50are am actually in small changes in
26:52intensity or inclination
26:54or changes in direction of Earth's
26:56strength field. Or you may depend on how
26:59the sensor work and we don't know that.
27:01So, it could be that a stronger stimulus
27:03with where everything changes a lot is a
27:05better stimulus. So, therefore we we we
27:08we alternate with those every 5 minutes
27:10to maximize the chance of activating
27:14magnetic receptors.
27:16Thank you, Henrik. And anyway, the birds
27:19needed intact trigeminal nerve for this
27:23activation to occur in the brain and it
27:26was first done in robins and now there
27:30are data published on pigeons and
27:33northern wheatears. So, it's and they
27:35show the same pattern. So, it seems to
27:37be a very robust phenomenon. Yes,
27:40please.
27:40Has anyone done like acute cultures of
27:42the trigeminal sensory neurons and
27:44applied magnetic fields
27:46in a petri dish to see if you get some
27:48kind of signal?
27:50Sorry? If you do an acute culture, if
27:52you actually dissect out the trigeminal
27:53without destroying the nerve endings,
27:57you could actually put it in a petri
27:58dish, record from it and show that it's
28:00activated in response to a magnetic
28:02field. Has anyone tried something like
28:04that?
28:05No, don't think so.
28:07There is No nobody has tried that, but
28:10there's a challenge with that because
28:13those neurons are very very long and
28:15they have all had their nuclei in this
28:18ganglion, the the the red dot on the
28:20left. This is like at the entrance of
28:23the brain. Yeah, so
28:24So, so they would be very very difficult
28:27to get out intact. In mouse uh
28:30models of chronic pain, people do this a
28:33lot where they have the whole foot
28:34attached all the way up to the spinal
28:36cord. Wow.
28:37It's the same thing. It's a very long
28:38structure, so it's totally possible to
28:40do. Okay, nobody has done that.
28:44So, it seems that uh
28:46uh trigeminal associated
28:48magnetoreceptors, they do exist even
28:51though we have to admit that we Yes,
28:53please. Sorry.
28:55Um has somebody tried to uh do
28:57electrophysiology in the region that are
28:59innervated by the trigeminal nerve and
29:01Oh, yes. And they did it
29:03Oh, yes. People have tried it and they
29:05had positive results. The problem is
29:08that when you are doing
29:10electrophysiology
29:11and your uh
29:13your stimulus is change of the magnetic
29:17field, you generate the electric
29:20current.
29:21And then it is extremely difficult
29:25to uh be really sure that what you uh
29:30that what you are observing are not the
29:32artifacts from your
29:34from your setup
29:36and uh uh
29:37but but real responses. And some people
29:41have
29:43done this and published this relatively
29:45high and then very serious labs
29:49have done a lot trying to replicate
29:52these findings and they I mean they were
29:55not believing their own results. So
29:57So uh it doesn't mean that I mean this
30:00is I would say this is notoriously
30:02difficult. But this is if you if you
30:04switch instantaneously the magnetic
30:07field, but if you have slowly varying
30:08magnetic fields like you know who and
30:10Dickman did it. If you really slowly
30:12rotate the magnetic field, then don't
30:14you get a DC shift, but you shouldn't
30:16have artifacts that look like spikes, so
30:19Probably. Probably. So so I'm not saying
30:21I'm not
30:21Dickman can't replicate their own
30:22findings. That's a different thing what
30:24I'm saying.
30:25Uh this is the way to go. If you're
30:26worried about artifacts, then don't have
30:28a jump in the magnetic field, but have
30:30it slowly vary. Yeah, I mean I
30:33I'm not a neurophysiologist. So if
30:35someone is going to overcome these
30:38technical challenges, it will definitely
30:40not be myself.
30:43Uh but I hope I think I think that it's
30:45doable. I think that it's doable. The
30:47question is how
30:49how difficult it is.
30:51Uh
30:52So, it seems that uh these uh these
30:55magnetoreceptors exist, but their
30:58structure and function are not have not
31:01been known.
31:02And what concerns structure, I know that
31:05people are working on that,
31:07but uh
31:08I'm not a
31:10uh
31:11I'm not a
31:13uh
31:13uh
31:14histologist, and uh again, people who
31:20uh who are going to find these
31:22structures, that will be definitely not
31:24myself, but I can do something about
31:27their function, because I'm doing be-
31:29I'm can do behavioral tests.
31:32And uh this is just uh to uh mention
31:35that
31:36uh
31:37that it's possible to condition uh
31:41uh pigeons in the lab
31:43uh for uh for the change of uh of
31:46inclination and intensity, and birds can
31:50perceive it has been shown in in the lab
31:52in lab experiments that pigeons they can
31:54perceive
31:56uh
31:56uh
31:57intensity and inclination of the field.
31:59Whether they are really using it for
32:01navigation is a is a different question
32:03on that. It's I'm not saying that they
32:05are necessarily using it, but they can
32:07perceive it.
32:08And I worked with another model. We were
32:12First, we
32:14uh I worked with Eurasian reed warblers
32:16or reed warblers, and these are mm the
32:19birds. And uh this is uh And then, I'll
32:22show you how we were able to show that
32:24these guys, they very probably use the
32:27magnetic map, and they use the
32:30information that is transmitted by the
32:32ophthalmic branch of the trigeminal
32:34nerve for their navigation. And now,
32:37someone asked, how do how do you choose
32:40a study species? And this is a nice
32:43example because no one has used
32:46reed warblers for orientation
32:48experiments before myself.
32:52Uh but reed warbler has uh
32:54it has a very interesting breeding
32:56distribution in Europe. It is common in
33:00this area. It is not a rare bird. You
33:02can capture them uh in Rybachy on the
33:05Baltic coast in reasonable numbers. It
33:08is so common that it is not a protected
33:10species. So, it is not it is not
33:12vulnerable. It is just a common species,
33:14not red-listed. So, it's possible to get
33:17a permit
33:19for working with them.
33:20And they breed they have they breed this
33:24is roughly their breeding distribution.
33:26They do not go very far east.
33:29They they are really western European
33:32species. They this uh there is another
33:35subspecies breeding in Kazakhstan, but
33:37it's another subspecies. We are not
33:38interested in it.
33:40So, uh what we did we uh captured them
33:44on the Baltic coast and we know from
33:46during recoveries that birds that
33:48migrate in spring through our area, they
33:51breed here.
33:52This is known from ringing recoveries.
33:54And we tested them in Emlen funnels
33:57during three consecutive years
34:00and they showed a very nice uh
34:03northeasterly orientation in Emlen
34:05funnels.
34:06Uh so, which was which was consistent
34:10what with what they are supposed to do
34:12in spring.
34:13And then, we physically displaced them
34:16by plane to Zvenigorod biological
34:18station of Moscow University.
34:21And when they uh when they were
34:24displaced,
34:25they were
34:27surely
34:28east or southeast of their breeding uh
34:32of their
34:33migratory goal. I I mean with robins you
34:36cannot do that. Well, you with robins
34:38you need to go very far because robins
34:40they breed all the way here.
34:42And I could bring them to
34:45uh to a place where the facilities were
34:47available and this place was east. So, I
34:51mean if the birds do not
34:53detect the displacement, if they are
34:56ignorant of the displacement, they
34:58should continue showing north easterly
35:01orientation in Emlen funnels.
35:03And if they detect the displacement,
35:05they should either go back
35:08uh
35:08west
35:09or northwest if they if they correct not
35:14to the capture site but to their goal.
35:18And
35:19these two directions are sufficiently
35:23different
35:24to be separate
35:26uh separable in Emlen funnels.
35:29Uh and this is why we we we we have
35:32chosen the these particular species and
35:34not and not garden warblers because
35:36garden warblers also breed here.
35:39Uh east
35:40also east of the Urals.
35:42And what we got, they indeed corrected
35:45for the displacement
35:47and they corrected to their
35:49towards their uh migratory goals and not
35:53so they
35:54they somehow realized where they were
35:58and they realized where their goal was.
36:02And these were intact birds
36:04physically displaced.
36:06And what we did next,
36:10we asked ourselves whether they need
36:13trigeminal transmitted trigeminally
36:15transmitted information
36:17to be able to do this.
36:19And then
36:21we
36:22uh
36:23did the similar experiment
36:25but uh half of the birds that we
36:29uh transported to Moscow
36:32uh had their trigeminal nerve up uh
36:34surgically ablated, and half of the
36:37birds were sham operated. And certainly,
36:39we had data from the previous
36:41experiment on intact birds. We didn't
36:43need to do intact birds again.
36:46And the result was that
36:50trigeminally ablated birds
36:52were not correcting for the
36:54displacement. And I think that this is a
36:56very important result because
36:58if they were
37:00uh randomly oriented, everyone could
37:03have said,
37:04"You have debilitated your birds so much
37:06that they are not no longer they no
37:08longer know where they are."
37:11So, the birds were fit enough
37:13to show spontaneous nocturnal
37:16migratory restlessness, and they were
37:18also oriented.
37:20Uh but, they were oriented not
37:23but, they were just doing the same as
37:25they were doing before the displacement.
37:28Uh
37:29sham section birds were unfortunately I
37:31mean, ideally, they would uh be they
37:34should uh be doing exactly the same as
37:36intact birds. We interpreted it as uh
37:41sh- sham section birds being not
37:43statistically diff- after displacement
37:45were not statistically different from
37:47intact birds, and uh real ablated birds
37:51were statistically different from intact
37:52birds, but certainly, I mean, the shams
37:56behaving not quite perfectly is one of
37:59the reasons why this paper is in PLoS
38:01One and not in a more posh journal.
38:05Yes, please. Uh where did you do the
38:07surgery in the
38:08capture site or in the No, we did the
38:10surgery at the capture site before the
38:12displacement.
38:13Uh the birds were uh ablated,
38:16then they uh rehabilitated, and were uh
38:20and were displaced.
38:23So, yes. So, I wanted to know that you
38:24don't have
38:25You have your I just really want to know
38:27if you have surgery before displacement
38:29and also after displacement and there's
38:31no difference. So, that We We only did
38:35surgery before the displacement.
38:37And
38:39uh
38:40probably it would be it would be a nice
38:43thing to do to have another group uh
38:45ablated after the displacement, but we
38:47didn't do that. And I can say that it
38:51was also It was also logistically
38:53challenging study because reed warblers
38:56they have a short migratory period.
39:00We They We can capture them in decent
39:03numbers since the 10th of May. We need
39:06to do uh tests uh at the capture site.
39:09We need to ablate them. We need to give
39:12them some time for rehabilitation,
39:14displace them, test them again. And
39:16after the 10th of June, they just stop
39:20being uh active. It is really I mean, it
39:23is for every
39:25for every student who is learning about
39:27uh annual cycles, it is it is very I
39:30mean, on on the 7th of June, they're
39:32perfectly oriented.
39:34On the 8th of June, not really. And
39:36since the 9th of June, they stop. I
39:39mean, just like
39:40turning a switch. So, we are very
39:42limited in time. We can only work
39:45during, say, 1 month in for for doing
39:47this experiment.
39:49So, at least our data suggests that uh
39:53trigeminal nerve
39:54transmits navigational information into
39:57the brain of reed warblers. And we
40:00thought that we could
40:03test whether this information was
40:05magnetic in the light of previous
40:07findings that uh trigeminal nerve
40:09transmits magnetic information into the
40:12brain of admittedly other birds because
40:15these studies were not done in
40:18uh in uh reed warblers.
40:21So, what we did, we uh
40:24used magnetic coils. We magnetically
40:27displaced the birds.
40:29And we were not the first ones to do
40:31that.
40:32People have uh done magnetic
40:34displacements before.
40:36Uh there are data from Australia
40:40with Australian silvereyes that were
40:43migrating during
40:45uh
40:46Australian autumn, so our spring, from
40:49their uh Tasmanian uh breeding
40:53uh breeding quarters to winter quarters
40:56in northern Australia,
40:57and they were captured
40:59in Armidale, and they were oriented
41:03towards the north.
41:04I mean, towards their winter quarters.
41:07And uh
41:08they were when they were magnetically
41:11displaced to northern locations,
41:13uh well, they behaved differently, but
41:17uh
41:18it was I mean, in this particular case,
41:21they were disoriented because this uh
41:23confidence ellipse includes zero.
41:26And there were uh other experiments
41:30uh when people uh
41:32uh
41:33captured uh in spring, this time it's
41:35European spring, lesser white throats,
41:39uh in uh Sweden and magnetically
41:42displaced them displaced them
41:44towards the south to Czechia, and
41:47towards the north beyond their breeding
41:49range uh to Norway, and the result was
41:53that birds magnetically displaced to
41:56Czechia was still oriented towards the
41:58north, and birds displaced towards their
42:02uh were still oriented towards the
42:03north, and the birds displaced to Norway
42:04were disoriented, but
42:07every time when the result when the
42:11response to a treatment is
42:13disorientation,
42:14one can claim uh non-specific stress
42:17effects.
42:18And well,
42:20it's difficult to say something against
42:22this interpretation. It can be a
42:24non-specific stress effect.
42:26So, what we uh did, we
42:30displaced the birds to uh
42:33uh Zvenigorod magnetically,
42:35where we knew Yes. I don't agree about
42:39that. I mean, I think that if uh there
42:41is a random distribution, it is not
42:43necessarily indicating a stress effect.
42:47Anna, I completely agree with you.
42:49Unfortunately, not every Not every
42:52reviewer agrees with that.
42:54It can happen two things. Either the
42:57birds go in a direction different from
42:59the goal,
43:00and they have
43:02some kind of
43:04non-sensory orientation, because it has
43:06been demonstrated and shown repeatedly
43:09on many species.
43:11And because of also sometimes the
43:14animals are attracted by some particular
43:16local feature
43:18uh when I when released in the field.
43:20But, it happens that the birds are
43:23disoriented, because each bird take a
43:26different direction. And so, this does
43:28not mean necessarily stress.
43:30Anna, I agree, and I try to think
43:32positive. I
43:34uh but but many people Many many nasty
43:37reviewers would say, "You cannot rule
43:40out a non-specific effect." And then So,
43:42if if they are disoriented, they tell
43:44you, "Well, but they are oriented in a
43:46different direction, and so maybe the
43:48effect is not
43:50So,
43:52there is a problem
43:53in that. I do not disagree. I do not
43:55disagree with you. But,
43:58Yes, please. I think that always you
43:59could exclude that the birds are
44:01stressed, right? You can document their
44:03behavior. You can look at any kind of
44:04cortisol levels, and that could like
44:06counteract that. Like you could look for
44:09other really like I would also say I
44:11would also say that when the birds I
44:13mean what we are studying is spontaneous
44:17nocturnal activity uh
44:19in captivity. And if the birds are
44:22really stressed and it happens from time
44:24to time, we don't need to tell it to
44:27tell it to
44:28uh to authorities, to animal welfare
44:31authorities, but it does happen. And
44:33then we know what happens. They they do
44:36not they do not show restlessness. They
44:38just sit on the bottom of the animal
44:40funnel.
44:41But uh
44:43I agree, but uh
44:45the fact is that
44:47many colleagues disagree, many reviewers
44:51disagree, and in order to persuade them
44:54uh it is better to have a predictable
44:58reorientation because then it's I would
45:01say that
45:02I would say that it's a stronger
45:03argument even though I agree that uh
45:06disorientation, so a different behavior
45:09is an argument in itself. I agree with
45:11that.
45:13Yes.
45:13I just want to say it might not be
45:14stress, it could be pain because
45:17in pain research the way that you create
45:20chronic pain in mice is you sever either
45:22the trigeminal peripheral afferent or
45:24branch or from dorsal root ganglion
45:27peripheral nerves. And that's what
45:29you're doing to the Well, we
45:31uh It could be something like that. Uh
45:34well, the birds are
45:36anesthetized. I mean certainly when when
45:38they when during the uh operation
45:41they're anesthetized.
45:43It's just after. It's all the process of
45:45seeing the nociceptive firing. Uh
45:47Again,
45:49it's theoretically possible, but again,
45:51I mean
45:52I mean a bird is rarely ill. A bird has
45:57uh uh uh
45:58songbird. They're either fine or dead.
46:02Uh
46:03and uh and the the period of time
46:05between being fine and being dead is is
46:08notoriously short.
46:10And another thing is that again, if the
46:12birds are stressed, in pain, I mean I
46:15mean really
46:17uh,
46:19really seriously inconvenienced, they
46:22would not
46:24be active in Emlen funnels. Because this
46:26is an activity which is shown
46:28spontaneously by the animals that are
46:32feeling quite okay. Well, we I don't
46:35know. I did a lot of research and
46:37they're prey animals, so they don't
46:39display when they actually are in a
46:40state of chronic pain that you can
46:41actually figure out really
46:43If they determine that they do have
46:44chronic pain, they're just not showing
46:46it the way that we do. And and then and
46:49then uh, I I well, you may claim that
46:53it's panic, but then it will be
46:55I would find it a very unlikely
46:58coincidence that a panicked bird uh,
47:02shows activity in the direction
47:04consistent with migratory reorientation
47:07and using a map that I'm going to show
47:08you just now. So, it
47:11things do happen, but I would say that
47:13it is a rather unlikely coincidence. So,
47:16Mhm.
47:17The comment about this uh,
47:19you know, what can you make out of
47:22this oriented distribution? So, I guess
47:24two comments. One is that if you look at
47:26the individual animals Mhm. and see
47:28whether they are still showing
47:30consistent uh, orientation, but just
47:33between animals is different. I think
47:35that'll be a stronger argument because
47:37if there is some stress effect, you'd
47:38likely they'll just most of the time do
47:40nothing. So, I think looking at the
47:41individual animal is important as
47:43opposed to this group phenomenon. And
47:45secondly, just as a comment, I mean it
47:46doesn't have to be stress. Could be that
47:48this nerve transmits whatever
47:50temperature information and you separate
47:52and then they think it's too hot or too
47:53cold and it's they don't feel like
47:55migrating. I mean, you just confuse
47:58them. I mean, not that that has to be
47:59stress, but you also got confusion
48:01effects, right? So, uh And
48:03with the reviewers in this respect. It's
48:04hard to How do you get something like
48:06that? And and I can tell you that uh in
48:09all the experiments uh in the
48:11experiments I have shown you before
48:15what people did
48:17I mean, in the uh in in in these
48:19experiments and in these experiments,
48:21what people did they kept the birds just
48:25in the normal aviary.
48:27They took it
48:28to the all to the funnel, which was in
48:31the altered field
48:33tested it took it back into the aviary
48:36with the normal field
48:38ambient field.
48:40Then next night, they took it again to
48:42the altered field and they did it
48:44several times.
48:46And if the bird indeed used the magnetic
48:49parameters for their positioning, it is
48:52equivalent
48:53of taking animal displacing
48:56instantaneously 1,000 km then back
49:00then forth again
49:01and if
49:02experiment. Yes. Yes. And if your if
49:06some of your senses is sending you
49:08impossible information
49:10a one idea to cope with it is to ignore
49:13this sense.
49:15And what we did, we kept the birds
49:18within the coils throughout the
49:20experiment.
49:22Uh we changed the field only once.
49:25And then we had to test them during
49:27several nights and during all of this
49:30time, the birds remained within the
49:33altered field.
49:34And you can see how the coils look like.
49:37There is not We had to take the birds
49:40out of the cages and put them on top in
49:42ambient funnels without taking them out.
49:45And uh
49:47as a result you can see that there is
49:49not much space between this table and
49:52the coils and I do not fit in.
49:56I could only take rather I accept rather
50:00slim students to do this work.
50:03Which is well, but it is you see
50:06how it looks like.
50:09I have a
50:11another question maybe. So, did you use
50:13for this you used only juvenile or adult
50:16or Uh
50:17it was spring and for the
50:20purposes of navigation these all these
50:22birds were adults. They were all
50:24returning I mean in read warblers in
50:27spring you cannot safely separate the
50:31second year birds and older birds but
50:34for the purposes of navigation
50:36experience they have all been born
50:40somewhere in the Baltics, went down to
50:43Africa and were returning were returning
50:45now. So, they were all experienced
50:48uh in spring.
50:50And uh
50:51we uh
50:52put the birds into the coils
50:55and we simulated the magnetic parameters
50:57typical
50:59of that area.
51:02Uh
51:02and uh
51:05everything all the rest all the other
51:07parameters were typical of the Curonian
51:09Spit. So, they had the same photoperiod,
51:12they experienced the same
51:14uh odors, they experienced the same
51:17stars, ev- uh the same landscape,
51:20everything was the same only the
51:23magnetic field was changed.
51:25And this is how it looked like on the
51:27dunes.
51:30And the result were the result was that
51:33the response to the
51:35magnetic displacement
51:37was indistinguishable from the
51:40results of the real displacement. So, we
51:43could magnetically displace birds
51:45really. I mean we everything was the
51:48same, only the magnetic field was
51:50changed, and we changed all the
51:51parameters. We
51:53simulated the magnetic conditions of a
51:56remote site, and the birds behaved
51:59exactly the same in the sense of uh
52:02migratory orientation and the funnels as
52:04if they were really displaced to that
52:06site.
52:08And uh
52:10we think that this is a rather strong
52:13argument in favor of the magnetic basis
52:17of the navigational map, at least in
52:19reed warblers.
52:21And uh
52:23now
52:25I want to show you this
52:27uh map, this analysis again.
52:30And you see that we are
52:33on the border between
52:36uh yellowish and green. So, in our area
52:40it should probably work with uh
52:43uh inclination and intensity alone, or
52:46it might work, but there are also other
52:48areas
52:50where people where birds do navigate,
52:52people also live, but birds do navigate,
52:55and here with these two parameters
52:58it is theoretically not possible to do
53:01that.
53:02And then, one possibility is to use
53:06magnetic declination. And magnetic
53:08declination is actually the difference
53:11between the
53:13geographic north and magnetic north. And
53:16we know from Henrik's talk that birds
53:18have both
53:20uh uh star compass, so celestial
53:23compasses, that provide them with the
53:26uh the with the geographic north, and
53:29they have a magnetic compass,
53:30which provides them with uh uh with uh
53:33magnetic north. And then, the question
53:36is, so theoretically, it should be
53:38possible for the birds
53:40to take the two readings and to compare
53:42them, but well,
53:44theoretically possible and
53:45experimentally demonstrated are two
53:47different things.
53:49And uh
53:50why is declination so tempting?
53:52It's because it's provides it varies uh
53:56along the east-west axis exactly in the
53:59areas
54:01that are problematic
54:03from the viewpoint of uh
54:05inclination and intensity.
54:07So, it would be a very nice solution.
54:11And uh
54:13I just want to show you
54:19It's a bit slow because ah now
54:22uh
54:22uh I can show you that uh
54:27how nice grid
54:30is formed by
54:32uh magnetic
54:34uh inclination and declination. You see?
54:37It's a very nice grid. It These These uh
54:40This is the presumed migratory path
54:43migratory route of
54:45a reed warbler
54:46and you can see that if they can use
54:49declination
54:50it would uh it would be great for them.
54:54And we
54:56did an experiment is in uh
54:59Yeah, declination and Yeah, yes. Yes,
55:01thank you. Sorry sorry. It's It's
55:03declination and intensity. And if they
55:05could use declination, it will solve the
55:07problem.
55:08It would provide birds. Yes, please.
55:11Yeah, just just a short question. You
55:13showed them that they're migrating
55:14between Baltic coast and further to the
55:17east in Russia. Now you're saying they
55:19they go to Africa, so
55:21In spring
55:23So, this is in
55:24in autumn they go to Africa. Okay.
55:27In spring they go
55:30further to Russia, but not very far.
55:33Which is which was the reason why why
55:35why we uh
55:36have chosen these birds, but they go to
55:39the north or northeast in spring and
55:42towards the south in autumn and they're
55:44long-distance migrants. They all winter
55:46in sub-Saharan Africa.
55:48They might not go
55:50further south of the equator,
55:52but they definitely cross the Sahara.
55:55Okay,
55:56and how does this look in Australia for
55:58instance where the inclination and
56:00intensity lines are almost parallel
56:01there, too? Is it a similar
56:04Do you have a map Uh
56:06We Sorry.
56:08It is What on the slide just now? I must
56:09have been writing furiously and missed
56:11it. Sorry. Uh You see, in Australia
56:14it's also fine. Absolutely.
56:17So
56:18Sir? Yeah?
56:20So, this seems to migrate in a
56:22trajectory that's always on top of
56:24regions in which you have both, right?
56:26The the lines. red and blue
56:28I mean, they're not passing anymore in
56:30uh
56:31For example, in in Africa where you have
56:33only regions
56:36one or the other.
56:38According to this map.
56:41I mean, this is this is I mean, this is
56:43how
56:44our populations migrate,
56:46but also do migrate here.
56:49Uh and here it will be
56:53You see, it will be
56:54confusing for for the eastern population
56:57There is an eastern subspecies. I mean,
56:59this is
57:00This is another subspecies Acrocephalus
57:02scirpaceus fuscus that goes down to
57:05East Africa. But you see, uh
57:09as Hedrick mentioned, there is probably
57:12no single solution which is good for
57:16every avian species on this planet.
57:20But at least for reed warbler for mm
57:24western European populations of reed
57:27warblers
57:28uh using declination would be a
57:31solution.
57:32And
57:33for many other birds, too. But I agree
57:37that there are
57:39places on Earth where this is not a
57:41solution and where birds need to use and
57:44other migrating animals need to use
57:47other
57:48cues.
57:50And we really did an experiment.
57:54We
57:55in autumn this time
57:58we changed declination. And what does it
58:00mean to change declination?
58:03Also in in in Meric coils.
58:05We just rotated the north.
58:08We only rotated the horizontal component
58:11of the magnetic field
58:148 by 8.5 degrees towards the left.
58:18Anticlockwise. Because we have uh
58:22uh 5 degrees and a half in Rubachi.
58:25And if you just rotate uh
58:28uh
58:30uh 8.5 degrees, you have minus 3
58:32degrees. And it will correspond It's a
58:36It is a coincidence. But it will
58:38correspond an existing location.
58:41The vicinity of the town Dundee in
58:43Scotland have has exactly the same
58:46inclination and intensity as Rubachi.
58:50But they have a different declination.
58:53So So in other animal societies, birds
58:55that might have polarity compasses, how
58:58would you distinguish between an animal
59:00that's using a polarity compass and
59:02declination?
59:04In this particular
59:07uh In this particular case, I'm not
59:10speaking of compass at all, but you see
59:14uh
59:16If you have a technical compass,
59:18uh how do you know which end is north
59:21and which end is south?
59:25Based on polarity, right? No, it is
59:27based on the fact that someone has
59:29painted the north end. Oh, it's okay. If
59:32you have if you have just a needle
59:35not painted by anyone,
59:38it will just point downwards
59:41and in the northern hemisphere, it will
59:43be so it will be it will be oriented
59:45along the north-south axis.
59:48But and and you will know that in the
59:51northern hemisphere,
59:52the
59:53axis which is pointing downwards is
59:55north.
59:57When you go to Australia,
59:59you have the same compass, the same the
1:00:01same needle,
1:00:02and the
1:00:04end which will be pointing downwards
1:00:06will be pointing
1:00:08towards
1:00:09south. So,
1:00:11only painting one end of the needle
1:00:14makes it a polarity compass.
1:00:17Nah, I'm not so sure about that. I mean,
1:00:20if if you have a single magnetite
1:00:21crystal, it will have a polarity and so
1:00:24it it for for that that's like painting.
1:00:26It depends on on how the
1:00:30the biophysics of the of the crystal
1:00:31would give you it there would be a
1:00:33difference if you change the polarity
1:00:35this crystal would change by 180° and if
1:00:37it's attached to something inside the
1:00:39cell Then then yes, you would definitely
1:00:41Then then then yes, then yes. certainly
1:00:43possible but I think your question went
1:00:45in a different direction. I think that
1:00:47what you are saying is that of course
1:00:49now we are changing here the magnetic
1:00:51field 8 and 1/2 degrees
1:00:53counterclockwise.
1:00:54So, the compass response of these
1:00:56animals should now be shifted by 8 and
1:00:591/2 degrees. That's of course far below
1:01:01the resolution that we have in the in in
1:01:03the
1:01:04In animal phallus, you can never you can
1:01:05never detect it.
1:01:06You cannot detect it. Okay. So and so if
1:01:09your response would be 8 and 1/2
1:01:11degrees, it would just be a compass
1:01:13response but And then the needle will
1:01:15tell you it's not 8 and 1/2 degrees.
1:01:16Yes, I mean the the adults I mean these
1:01:19are the
1:01:20uh
1:01:21directions shown by adults and juveniles
1:01:24at the capture site uh all they were all
1:01:26tested in the capture site, but in the
1:01:28ambient field
1:01:30and they were oriented towards the
1:01:32uh
1:01:33west-southwest, which is their normal
1:01:36migratory direction in autumn in our
1:01:38era. And when we magnetically display
1:01:41when we change declination
1:01:43uh or magnetically displace them to
1:01:46Scotland, where they have never been,
1:01:48adults responded by changing their
1:01:51direction by 150°.
1:01:55Uh you can see that I mean, this is
1:01:58obviously not a compass response because
1:02:01uh compass response would have been only
1:02:038.5° and undetectable in the mm
1:02:07in in Emlen funnels, and juveniles were
1:02:10perfectly disoriented,
1:02:12which uh which is interesting because
1:02:16I mean, if they were
1:02:19only relying on their
1:02:22compass and clock, they would be
1:02:25expected not to respond at all.
1:02:28And it seems that even though they were
1:02:31migrating for the first time in their
1:02:33lives, they had some expectation
1:02:36what uh declination should be.
1:02:40And adults, they have not been in
1:02:44Scotland before because the Baltic uh
1:02:48reed warblers do not migrate through the
1:02:50British Isles,
1:02:51but they most probably had experienced
1:02:55negative declinations in Africa
1:02:59during their previous migration. And
1:03:01from declination, they could tell that
1:03:05they are
1:03:06either far in the west or in the south,
1:03:10but intensity and inclination obviously
1:03:14were wrong for a southern location.
1:03:17So, uh
1:03:19it suggested a western location and
1:03:21reorientation towards the
1:03:22east-southeast.
1:03:24I'm a bit confused about the
1:03:26declination.
1:03:27How can you use that? Because I mean the
1:03:29angle between the geographical north and
1:03:31the magnetic north. Now, if you're in
1:03:32northern Canada, then the difference is
1:03:35big and then it's useful. But if you're
1:03:38talking here about this about difference
1:03:40in Revathi 5°
1:03:43and in Scotland it's minus 2°, so 7°.
1:03:46Then you assume that they are able to
1:03:48detect both the northern star rotating
1:03:52stars, I guess, and or sunset or
1:03:54something from geographical information
1:03:56and the magnetic compass to within a
1:03:59very high precision. So, it will I mean
1:04:01except expected very accepted very
1:04:04you know, polar regions, this is a very
1:04:07very small difference. Well, I The point
1:04:10is shows that it's it's perpendicular to
1:04:12the intensity, but it's a very very
1:04:13small signal. I agree. Well, I do assume
1:04:17that they are able to use their
1:04:19compasses
1:04:20with a precision of around 1° or better.
1:04:24Because I would argue that
1:04:28compass with an uncertainty of 10-15°
1:04:32would be as useless as no compass at
1:04:34all. But the parabola that Henry was
1:04:37showing us is is not 1° precision. It's
1:04:39worse than that. Okay, but there are
1:04:41many many factors going into those ring
1:04:43recoveries. This is of course that a
1:04:45bird only flies 10 m/s. So, on most days
1:04:48at the height they are flying, the winds
1:04:50are stronger than their flying speed.
1:04:51So, they of course affected by winds.
1:04:54They you are of course there is a
1:04:55distribution in the individual birds
1:04:58inherited direction. So, they are not
1:05:00all inheriting 212°. I think that's
1:05:03unrealistic.
1:05:04Likewise, the but it's probably not much
1:05:07spread there either.
1:05:08And then of course there are the
1:05:11the mistakes you are making. There are
1:05:12many many things that go into the ring
1:05:14recoveries, which does not mean that the
1:05:17sensory system in principle cannot
1:05:19detect the very specific direction.
1:05:21Because if you look at the star, if you
1:05:24ask you to go out, even though you don't
1:05:26need to use it, you have to point to the
1:05:29North Star. Once you know the geometry
1:05:31of the North Star, your precision is a
1:05:33degree. I mean, no problem. I mean, it's
1:05:35very easy to do.
1:05:36What I would say is that, you know, that
1:05:37then the variation in the ceiling cost
1:05:39of population could be due to kind of
1:05:41individual differences. This just points
1:05:43to me again the importance of tracking
1:05:44individual animal, you know, with GPS
1:05:46and seeing if they are going straight
1:05:47within 1 degree. I mean, this would be
1:05:49the answer.
1:05:50No, but they will not because there are
1:05:51all kinds of other factors that will
1:05:52throw them off course.
1:05:53This would be this indication of how how
1:05:55good
1:05:57like an up an upper limit on how good it
1:05:58can be. Yes, please. So, are you
1:06:00planning to do the opposite, like change
1:06:03the declination by changing the star
1:06:05pattern?
1:06:06That would be the obvious experiment,
1:06:07right?
1:06:08Uh well, in order to change declination
1:06:11by changing the star pattern, I need to
1:06:13go to a planetarium. Yeah, or use like
1:06:15the simplified version with the lights
1:06:18that hand the drill.
1:06:21That's a very logistically challenging
1:06:23experiment. Hand-raising enough birds to
1:06:25get significant results of something
1:06:27like that is a huge challenge
1:06:29practically.
1:06:30And I I am also I can say that I'm more
1:06:34cautious than Henrik about artificial
1:06:37patterns. I want to I as long as it's
1:06:40possible to work under the real sky, I
1:06:42really want to do that. I'm not
1:06:45Did you try to to put some
1:06:48shield for overcast to create an
1:06:51overcast, so that they cannot see the
1:06:53stars?
1:06:55Uh well, in these experiments, we were
1:06:57specifically looking at the effect of
1:07:00declination, whether whether
1:07:03uh
1:07:04changing declination would change the
1:07:06situation.
1:07:07And
1:07:09And uh therefore, we tested them under
1:07:11open skies.
1:07:13And
1:07:15And without without milky glass.
1:07:18Uh Yeah, but to see whether it's really
1:07:21declination, you need to exclude the
1:07:24possibility to detect the magnet
1:07:27geographic north. Yes. Yes.
1:07:29the geographic north, you can detect it
1:07:31only if you Yes. Yes. Yes, certainly.
1:07:33You need celestial cues.
1:07:35So, it would It would be really nice to
1:07:38show that if they cannot see the stars,
1:07:40they are disoriented or oriented. There
1:07:42is There is another logistic problem.
1:07:45And the problem is that you need to
1:07:47deprive them of the view of the sky not
1:07:50only during the test itself,
1:07:53but also throughout the period of
1:07:56keeping them because they may detect
1:08:00that they
1:08:01are They may decide that they are
1:08:03displaced towards the west
1:08:06before
1:08:08before actual
1:08:10uh
1:08:11test.
1:08:13And move and decide to move towards the
1:08:16east-southeast and then maintain this
1:08:19east-southeasterly direction on the
1:08:21basis of the magnetic compass, which is
1:08:23available to them. So, the So, in order
1:08:26to do this, I would need to keep them
1:08:30uh to keep them without access to the
1:08:33sky to the view of the sky throughout
1:08:35the experiment after the magnetic
1:08:38displacement. And then the problem is
1:08:40that specifically reed warblers,
1:08:43when they don't see the sky for a long
1:08:45period of time, they stop being
1:08:47oriented. We have tried this, and we
1:08:50know that if you keep them
1:08:52uh indoors for a long period of time, so
1:08:56for 5 days, 3 day Well, 3 days maybe not
1:09:00yet, but for 5 days, 7 days, they're
1:09:02disoriented. Well, indoor I can
1:09:04understand, but I I don't think if you
1:09:06put some
1:09:08opaque glass or dark or
1:09:12plastic, whatever.
1:09:14In order that to to simulate overcast. I
1:09:16mean, not not to show them the stars.
1:09:19Or a screen, whatever. I mean, you you
1:09:22then you have really the evidence that
1:09:24it's declination. It's a matter of
1:09:27declination. Because then they cannot
1:09:29detect the magnetic the geographic
1:09:31north. I agree. I agree. I still think
1:09:34that even in this experiment, it could
1:09:36only be declination because it was the
1:09:38only parameter that we changed. But
1:09:41because there was no other parameter
1:09:42changed
1:09:43except of declination. But I agree that
1:09:47it will be possible to put uh
1:09:49uh to put milky glass on top of the
1:09:52Emlen funnel, but I'm afraid that this
1:09:54the results would be would be not
1:09:56necessarily conclusive of this
1:09:58experiment, but we can talk about it
1:09:59later.
1:10:00Because I
1:10:01have no time, and I need to skip large
1:10:04parts of my talk, but I just wanted to
1:10:07emphasize that magnetic maps are used
1:10:10not only by the birds.
1:10:12There are some nice data showing that uh
1:10:17loggerhead turtles that uh I mean, and
1:10:20these are hatchling loggerhead turtles
1:10:22that uh
1:10:24need to stay within the North Atlantic
1:10:26gyre, and when uh people in
1:10:30from uh North Carolina simulated
1:10:34magnetic conditions at different
1:10:35locations uh of the uh of the North
1:10:38Atlantic gyre, the uh
1:10:41uh hatchling turtles responded by uh by
1:10:45uh
1:10:46swimming in the direction that would
1:10:48keep them within the gyre and not being
1:10:51transported to
1:10:53the North Atlantic, where they would
1:10:55die.
1:10:56There are also
1:10:57data
1:10:59uh on green turtles that responded in a
1:11:03predictable way to the magnetic
1:11:05displacement
1:11:06in similar experiments. There there is a
1:11:09recent paper on eels that well that are
1:11:13claimed to
1:11:15uh
1:11:16respond uh
1:11:18respond uh
1:11:20by swimming to into different directions
1:11:22to
1:11:23uh
1:11:25uh to magnetic displacements.
1:11:28There are also data suggesting that
1:11:30newts
1:11:31uh use a magnetic map and these results
1:11:34are
1:11:35truly impressive and unexpected because
1:11:39newts never move beyond 1 to 3 km
1:11:43and magnetic map varies
1:11:45uh on a spatial scale and much greater
1:11:48spatial scale. So, I mean the results
1:11:51are here, but it is very difficult to
1:11:54imagine how these animals could have
1:11:57developed a magnetic map
1:11:59uh
1:11:59given the spatial range of their
1:12:02movements.
1:12:03And there are also data with uh spiny
1:12:06lobsters
1:12:07uh and again
1:12:10again these animals that at least that
1:12:13don't move that much were also able able
1:12:16to
1:12:17respond uh in a predictable way. And I
1:12:20can say that
1:12:22it is not it is more than just one bit
1:12:24embarrassing that we bird people
1:12:27obtained relatively good evidence for
1:12:31migratory birds using
1:12:34uh
1:12:34using magnetic map after turtle people
1:12:38have obtained their data because the
1:12:41first
1:12:42suggestion that uh birds may use a
1:12:45magnetic map dates back to 1859.
1:12:49It was only a suggestion back then,
1:12:52but it took us
1:12:54more than 150 years
1:12:56to provo- to produce uh experimental
1:12:59evidence,
1:13:00and people working with other groups of
1:13:02animals were faster. So, it's it's a bit
1:13:05embarrassing, I should say.
1:13:07And uh then there is another thing, and
1:13:09the thing is that uh
1:13:13uh magnetic map is changing.
1:13:15And this is one reason why uh and then
1:13:19and then there is a question of
1:13:21precision of the magnetic maps.
1:13:23And this is an example
1:13:26uh
1:13:27of uh a turtle that needs to get back to
1:13:31breed on the Ascension Island.
1:13:33And with turtles that breed that lay
1:13:36their eggs
1:13:37uh
1:13:38on the coast of of the continental
1:13:41coast, it might be less of a problem
1:13:43because if when they return after 25
1:13:46years
1:13:47to lay their eggs, they would be just
1:13:49shifted by say 100 km or 150 km, well,
1:13:53it's not too good, maybe, but it's not a
1:13:56disaster.
1:13:58And for a turtle that lays its eggs
1:14:01uh on a small oceanic island,
1:14:04uh it will be a disaster, but it will be
1:14:06not able to find uh
1:14:08its uh its island.
1:14:10And this is uh a map that shows uh
1:14:14magnetic isoline that runs from Brazil,
1:14:17where these
1:14:18turtles
1:14:20uh
1:14:21forage and spend their time,
1:14:23and uh this is the uh situation in '85,
1:14:28and this is the situation in 2010.
1:14:31And now, after 25 years, the isoline
1:14:34does
1:14:35doesn't uh cross the island any longer.
1:14:38It has shifted.
1:14:39However, people have uh
1:14:42uh
1:14:43modeled
1:14:44this situation, and they assume that
1:14:48if there is a water-borne odor plume
1:14:51that emanates from the island, the
1:14:54uh
1:14:55uh the isola- the magnetic isoline would
1:14:58be still sufficient
1:15:00not to hit the island, but to hit this
1:15:02plume.
1:15:04And in this particular case, it would be
1:15:06a solution, but it would then mean
1:15:09that a turtle needs a two-step
1:15:12navigation
1:15:13because it would not be able to find the
1:15:16island on the basis of its memorized
1:15:20magnetic parameters alone. It would need
1:15:23It would only able to find the more or
1:15:25less general vicinity.
1:15:28And uh
1:15:29with a spatial resolution of the
1:15:32magnetic map,
1:15:33I want to
1:15:35show you this paper, this review. I came
1:15:39into orientation and navigation from
1:15:41ecology. I did my PhD on the polar
1:15:45ecology of migrating birds and identify
1:15:48myself
1:15:49as a bird migration person with a
1:15:52special emphasis on orientation
1:15:54navigation.
1:15:55And because of that, I'm I know a couple
1:15:58of papers from the field of ecology and
1:16:01I think that
1:16:02that spatial scaling
1:16:04is very important not only in ecology,
1:16:08but also in the study of animal movement
1:16:11and orientation navigation.
1:16:13And uh what we did recently, we looked
1:16:16at the
1:16:17uh at the uh data of how magnetic
1:16:22parameters vary over time. There are
1:16:24very nice uh data sets freely available
1:16:28to anyone from the magnetometric
1:16:30stations.
1:16:31They measure since '91.
1:16:34Uh and they measure the magnetic field
1:16:36every minute.
1:16:38And we took I won't go into details, but
1:16:42uh
1:16:42this is an example of a data from a
1:16:45Nurmijärvi station not very far from
1:16:48Helsinki.
1:16:49And you can see
1:16:51how it varied from 191 to 2015.
1:16:56And uh
1:16:57these are uh fluctuations between
1:17:00minimal and maximal minimal and maximal
1:17:02values.
1:17:03And this is And this is total field
1:17:05intensity.
1:17:06And variation is not negligible, and our
1:17:10analysis I won't go into much details,
1:17:13but our analysis shows that a pied
1:17:16flycatcher
1:17:17that uh
1:17:18imprints or remembers magnetic
1:17:21parameters somewhere in southern Finland
1:17:24that would try to return on the basis of
1:17:27the magnetic information alone next
1:17:29spring
1:17:3020 because of the There is also, as you
1:17:32can see, there is also a trend.
1:17:35Uh
1:17:36which is maybe less of a problem for
1:17:38birds, but is a problem for long-lived
1:17:41animals like turtles.
1:17:44Uh and uh over
1:17:46uh
1:17:4725% will return within
1:17:50-20 -8 km, which is means that they will
1:17:54not reach their destination. They will
1:17:56need to
1:17:57fly a little further, and 81.1% will
1:18:00return to within
1:18:02uh
1:18:0326 km. And it's a bit different in
1:18:06different parts of the world because the
1:18:08migrate the gradients are
1:18:11more steep or less steep, but uh even
1:18:14assuming perfect measurements of the
1:18:16magnetic parameters,
1:18:19uh
1:18:20no animal will be
1:18:22will be able to navigate with a pinpoint
1:18:25accuracy.
1:18:26They must and uh in real world,
1:18:29certainly,
1:18:30uh they cannot remember the value
1:18:33perfectly, and they cannot measure the
1:18:35value perfectly. I mean, this was the
1:18:37best case scenario with uh
1:18:41uh with
1:18:43uh
1:18:44uh good magnetometer and perfect memory.
1:18:48And in reality, uh living animals will
1:18:51be worse like uh than that.
1:18:53And it will mean it will mean that uh
1:18:57uh that they need something else. They
1:18:59will They would They would be able to
1:19:01find the area.
1:19:03It will be varied between different
1:19:05areas, but as a rough approximation, 50
1:19:07km by 50 km.
1:19:10And within this range, they will need to
1:19:13use other
1:19:15navigation systems. And it might be
1:19:18landmarks, not necessarily visual.
1:19:21And if uh if I'm breeding on the
1:19:24Curonian Spit, it's fine because
1:19:26Curonian Spit and Curonian Lagoon have
1:19:28very distinct topographical features.
1:19:31But birds
1:19:33uh are also, for instance, pied
1:19:34flycatchers, they show very high uh
1:19:37degrees of uh fidelity to their breeding
1:19:41areas in the center of Siberia. And I've
1:19:44flown into that area, it's just forest
1:19:47everywhere.
1:19:48So, topographic feature if you uh if you
1:19:51have found and they and they and they
1:19:53are site faithful.
1:19:54And uh if you have found
1:19:57uh a square 50 km by 50 km,
1:20:01uh
1:20:02it will be a challenge. They will need
1:20:03something else. It might be olfact-
1:20:06olfactory map, this I don't know, but it
1:20:09cannot be magnetic map alone. It is
1:20:12it is uh ruled out on the physical
1:20:16grounds. We cannot do anything. I mean,
1:20:18the the uh
1:20:20uh geomagnetic field is as it is. And
1:20:23neither we nor birds can change it.
1:20:26Uh
1:20:28So, that would imply then that any
1:20:29attempt by engineers to create an
1:20:31alternative GPS system based only on the
1:20:33magnetic field of the earth. This dude
1:20:35is failing. Uh at least you won't be
1:20:37able you won't be able to drive a car
1:20:40with with such a navigation system.
1:20:42Uh it might be it might be better than
1:20:45nothing,
1:20:46but it will definitely not allow you to
1:20:49drive a car or uh which is maybe not a
1:20:54too bad a thing, it will be it will be
1:20:56not precise enough to to be used for
1:20:58military purposes. Because then you will
1:21:00hit
1:21:01some
1:21:03some targets 50 km from their intended
1:21:05target, which is which is not okay in
1:21:08the more in the modern warfare.
1:21:10Uh
1:21:13Yeah, yeah, yeah, some 70 years ago they
1:21:15thought it was okay.
1:21:17Uh
1:21:21Uh Okay. Uh
1:21:24I I'll go very fast through the uh end
1:21:28of my talk.
1:21:29Uh
1:21:32This is the idea of clock and compass
1:21:34concept.
1:21:36Uh and uh it is a paper published by Ebo
1:21:39Gwinner and Wolfgang Wiltschko some
1:21:41nearly 40 years ago, where they showed
1:21:44that garden warblers hand raised in
1:21:46southern Germany,
1:21:48they show in Emlen funnels they showed
1:21:51orientation
1:21:52uh
1:21:54consistent with uh with the directions
1:21:57that their free flying conspecifics were
1:22:01taking in the wild at the same time. So,
1:22:03in early autumn the birds were oriented
1:22:06towards the southwest when uh Central
1:22:08European garden warblers were flying
1:22:11towards the Iberian Peninsula or
1:22:14uh Morocco mm in uh in the in the first
1:22:18part of autumn, and after that when uh
1:22:22their free flying conspecifics were
1:22:24crossing the Sahara towards the
1:22:26uh south
1:22:28Uh, the birds were doing the same in
1:22:30Emlyn funnels and it was the paper that
1:22:33helped shape the clock and compass
1:22:35concept saying that
1:22:38juvenile birds that migrate for the
1:22:40first time in their lives have no idea
1:22:42where they are. They only have a compass
1:22:45which tells them
1:22:47where to go and maybe clock is not a
1:22:50very good bird, I would say a calendar
1:22:53that tells them that
1:22:55you have 10 days to go this direction
1:22:57and then
1:22:58And that's fine. But there is there are
1:23:02some data sets
1:23:03that suggest that maybe some birds
1:23:07uh,
1:23:08do know where they are.
1:23:11This is a study in thrush nightingales
1:23:14done uh, some 15 years ago by Swedish
1:23:17colleagues
1:23:18who were able to show they did not use
1:23:22orientate uh, they didn't test
1:23:23orientation of these birds.
1:23:25But uh, birds but thrush nightingales
1:23:29inexperienced uh, migrants
1:23:31that were um, that had uh, the magnetic
1:23:34conditions along their migratory route
1:23:36simulated
1:23:38also down to northern Egypt they uh,
1:23:42deposited more fat
1:23:44and the interpretate than birds that
1:23:46remained in the
1:23:47in the magnetic field of Sweden and the
1:23:49interpretation was that uh, they were
1:23:53aware of the fact that they had to cross
1:23:56the Sahara.
1:23:57And uh, it's certain it's also a
1:23:59question. I mean, if you are
1:24:02non-experienced migrant how do you know
1:24:05when
1:24:07when the easy parts ends
1:24:10and you are going to cross the Sahara or
1:24:12the Gulf of Mexico and you cannot go on
1:24:15low fuel.
1:24:17Yes?
1:24:18I think there is one important
1:24:20distinction of that experiment
1:24:22uh, is that this may be an inherited
1:24:25signpost. Like an inherited value to
1:24:29switch a behavior. It doesn't have to be
1:24:31a magnetic This is exactly This is
1:24:33exactly what I'm going to say.
1:24:35Sorry. Uh, so that, uh, it does not need
1:24:39to be a detailed map. But it might be
1:24:43inherited knowledge
1:24:46of a beacon or a signpost
1:24:48that all we could call it a rudimentary
1:24:53rudimentary magnetic map or magnetic
1:24:56information which is used
1:24:59for
1:25:00for navigation, but not really a
1:25:03position-finding mechanism.
1:25:05There is a more recent study
1:25:07uh, in northern wheatears that had
1:25:10not exactly the same results, but, uh,
1:25:14the wheatears that, uh, remained in the
1:25:17in the magnetic field, uh, of
1:25:20Wilhelmshaven in, uh,
1:25:22northwestern Germany,
1:25:24they showed more migratory restlessness
1:25:27than the birds that had, uh, their, uh,
1:25:30their, uh, journey
1:25:32uh, magnetically simulated. And the
1:25:35interpretation of the authors is that
1:25:38these birds were aware of the fact that
1:25:40they were behind the schedule,
1:25:42which assumes that they do have a
1:25:45schedule.
1:25:46Which magnetic, uh, conditions should
1:25:49they meet in what parts,
1:25:52uh, of their of their first, uh, maiden
1:25:55journey.
1:25:57So, uh,
1:25:58it is highly unlikely that the birds or
1:26:02any other animals can inherit a magnetic
1:26:04um,
1:26:05magnetic map because, uh, the magnetic
1:26:08map of your parents is clearly outdated.
1:26:12It's outdated even for birds, but for
1:26:14turtles it's definitely outdated, badly
1:26:17outdated, so you are not you do not want
1:26:20to listen to
1:26:23to Beatles music anymore if you are if
1:26:25you are young.
1:26:26Uh maybe maybe you do, but uh it's it's
1:26:30outdated.
1:26:31Uh but uh
1:26:34Uh but there might be some magnetic
1:26:38information that is inherited and which
1:26:40helps for instance to prepare for the
1:26:43difficult part.
1:26:45And the take-home messages are that at
1:26:47least some birds use a geomagnetic map
1:26:50for long-distance migratory navigation.
1:26:53These are sea turtles and probably
1:26:55other animals do the same.
1:26:58Uh so it's not limited to birds.
1:27:01Uh in birds, navigation-related magnetic
1:27:04information is transmitted through the
1:27:06trigeminal nerve.
1:27:08This is the embarrassing part. We don't
1:27:10know the receptor,
1:27:12which is which is bad.
1:27:14Uh
1:27:15geomagnetic field alone cannot be
1:27:18responsible for the navigation with the
1:27:20accuracy which is known for migratory
1:27:22birds. There there must be something
1:27:24else.
1:27:26And uh magnetic map needs to be learned
1:27:29individually and you in every
1:27:31generation, but some inherited signposts
1:27:34or beacons may exist.
1:27:37And with this, I would like to
1:27:41uh thank you for your attention and also
1:27:43to thank So, my feet are on the Kuril
1:27:47spit and my head is in the vicinity of
1:27:49Moscow.
1:27:51Uh and I'd like to people with whom I
1:27:53have collaborated, some of them,
1:27:56and these are the ones with whom I have
1:27:59collaborated
1:28:00most.
1:28:01So, thank you and

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