with Prof Adrian Craig
From old speculations, and observations of birds in other places when they are not at their breeding sites, we now have many different approaches for describing their journeys. In particular, individual birds may be tracked throughout the trip, which has produced some very surprising and exciting results. These will be especially important in conservation as both their world and ours continues to change.
Welcome to everyone that’s attending tonight from right across the world we’ve got people from the USA from the UK from Portugal and Europe and all over um we’ve got some from Africa but most people are from South Africa um in this talk welcome and a special mention to the Das
Cross Bird Club which is Adrian’s Bird Club as well as my Bird Club um this is the coastal Branch they logged into our webinar on a big screen in the hall so welcome it’s good to have you tuned in I’m Lynette Redman and I’m coming to you live from
Greson in South Africa this webinar is being recorded and it will be posted on our YouTube channel the learn the birds channel in a few days time please post any questions or interesting comments in the comment section below and Adrien will answer your questions now we have a very special
Guest speaker Adrian Craig I’ve known Adrian for many years um we’ve been in the same Bird Club and Adrian’s Adrian is a real bird expert he knows his stuff he’s a retired professor of zoology and he spent his working career lecturing at roads University here in South
Africa Adrian has given many talks to bird clubs and school groups and other clubs and he’s even done a webinar for learn the birds last year on honey guards and honey hunters and it’s on our YouTube channel if you want to see it it’s it was an extremely interesting
Talk I learned so much about honey guides um Adrian’s research has always focused on African birds and it’s involved field studies Museum specimens and studies um of historical reports of birds and apart from his s formal scientific Publications he has written many popular articles for birding magazines he’s contributed to handbooks
Such as the birds of Africa as well as the handbook of the birds of the world so he’s very well-published Adrian tonight your talk is about such an interesting topic bird migration and where do the birds go I know long ago people used to see the birds vanish when the weather turned
Cold and they had no clue where they had gone and suddenly they arrived back in spring so there were all sorts of theories people really didn’t know so we really looking support your talk over to you Adrian right thanks very much for the introduction Lynette and welcome to
Everyone I would like to focus on just two topics tonight looking first of all at where these Birds go this map which you see here comes from an old edition of National Geographic and it focuses as one would expect on Africa in the Center showing particularly the sort of African and
Asian roots and giving some idea of the diversity of birds that undertake these long Journeys every year so tonight I’d like to try and deal briefly with some idea about where the Birds Go in particular about what we’ve leared about what individual birds are doing on these trips and then look a
Little bit about navigation how they find their way because this is an interesting example of the way in which science sometimes fumbles along gets stuck goes down blind alleys and very often advances are related to developing new techniques new skills but also new equipment which enable us to do different
Things first of all just sorry we’ve skipped a bit a reminder of migration in Birds is a return trip between the breeding area and the non-breeding area this gets us away from the problems with Seasons winter and summer because some birds of course move within the same hemisphere
So it’s not necessarily a change of season but some birds move extraordinary long distances and it’s a return trip undertaken by the same individuals there are other animals which migrate and interestingly some of these are even insects here we have movements that occur across the Indian Ocean involving dragonflies where dragonflies from India
Pass over islands in the Indian Ocean and land up in East Africa and later other dragon flies not the same individuals take advantage of different wind patterns to cross back from Africa to India but the birds we’re going to be dealing with of course it’s the same individuals and
They may make many Journeys during their lives so first of all a little bit history we have all heard of some of the early observations by for instance lenus who was famous for developing the naming system that we still use for animals and plants now lenos was a very distinguished
Botanist his particular area of experties was the Flora of lepland in Scandinavia but he had veryy strange ideas actually about bird migration below bl’s picture you can see a collection of barn swallows and many people in Europe were of course familiar with barn swallows because they often
Nest on buildings around people and they would have seen them for the last time probably flying low over the water collecting insects before they set off on migration and then they would disappear and suddenly would reappear again the following spring so lenus actually supported the rather bizarre
Idea that these birds dived into this into the water hibernated underwater and then reemerged again the following year now this doesn’t make a great deal of sense in biological terms but it’s to say he was a much better botanist than he was a zoologist at the same time that lenus was
Suggesting this rather bizarre explanation for the swallows another botanist Michel adanson spent several years in senagal in West Africa he was a very fine botanist he has the bab tree ad ins Sonia named for him and he was clearly a very good naturalist unfortunately he doesn’t seem to have been particularly interested in
Birds in his book on his years in senagal he devotes just eight pages to dealing with the bird life he also collected shells and he spends more than 40 pages talking about his shell collection but just in passing he noted that the swallows and the European Bea
Which he knew from France were present in synagogue during precisely the months they were absent from France and his conclusion was that these were clearly the birds from France who had migrated southwards to Africa and were present there during the time when they were absent from their breeding
Sites this would all of course have been in the same hemisphere because it was still north of the equator some of the first direct evidence came in the 19th century this unfortunate stalk shown in the left in a contemporary illustration in the right actually the museum specimen which is
Still in the rosock museum in Northern Germany this bird got shot with an arrow very large arrow and somehow managed to fly all the way back to Germany it was then duly collected as a curiosity and ended up in a museum but comparing the arrow to material that had been collected from
Africa by anthropologists people concluded that this stalk had been in the Sudan which was where arrows of this type were used by local people so there was some direct evidence of where individual birds might actually go but the first big breakthrough came with bird ringing which was established in Europe in
1899 in 1948 the first birds were ringed in South Africa and it depends on a unique ID number assigned to a particular bird and obviously International Co collaboration by different ringing units and this goes far beond Beyond normal International interactions during period for instance when South Africa did not
Officially communicate with Russia this was many years ago under the previous um apartate government every year the Russians sent a large file of South African ring Birds recorded in Russia to the British Museum who then forwarded it to South Africa and the South Africans reciprocated by the same route and when official
Relations were reestablished after 1994 one of the first things that happened was that Russian ornithologists invited South Africans who had ringed many Russian migrants in South Africa to join them on a field trip in the breeding grants from an individual point point of view we can use color ring combinations to identify individual
Birds this requires the use of several Rings if you’re going to ring large numbers of birds and there are problems because the colors fade over time and the birds can lose one ring which then makes their combination ambiguous so what has proved very much more successful being what we call alpha
Numeric rings as you can see on this little bird it has a single letter in this case the the ring is not very well positioned but if your eyesight is good you can work out that it says S6 so a single number and a single letter and these can be read through a
Telescope and with modern photographic equipment they can be photographed so this has been highly successful because in Europe there are many people who go out with powerful telescopes to watch birds and they can then record sightings of individuals but the St tends to focus attention on where the birds start out
And where they fetch up but not about the root in between so he has the bond swallow which has as you can see a huge breeding range across North America and Eurasia the North American birds go south to South America the Eurasian Birds Go South into Africa into tropical
Asia and the australasian region including Northern Australia the diagram to the right shows ringing records for European swallows found in South Africa Africa and we can see that they come quite a lot from the UK where there’s very active ringing community and where the chances of birds
Being found is quite high but also over a very wide range of Europe and right out into Siberia there are birds which have moved between the eastern part of the range and South Africa before I go any further and before anyone thinks that I have taken a lot of
Rather good bird photographs I’d like to pay tribute to my friend and colleague War tton seen in the bottom corner of this picture War has very generously over many years allowed me to use any of his slides to illustrate these sort of talks as you will see he’s a very fine
Photographer and the great majority of the pictures of birds which are I will show here were taken by him and absolutely none of them were taken by me another bird for which ringing gave us first clear indication of dramatic differences between populations was the white stalk here it soon became clear that
There were two distinct groups breeding in Europe there were Eastern stalks who flew eastwoods and then through over the Middle East down the Nile Valley and these were the birds who fetched up in eastern and southern Africa and there are Western stalks who crossed primarily at the stets of jaala the narrowest crossing
Point some of them actually stop off in Spain some go to North Africa but the birds which turn up in West Africa come from this population and it soon became clear that this was an inherited characteristic that Eastern stalks their offspring would always migrate along the Eastern route stalks because of their
Style of flight the way they saw avoid Crossing large areas of water because then they have to Flap actively and it’s much more efficient from their point of view to so without using much Wing movement and this works only over land so they minimize water Crossings as far as
Possible now once we had satellites circling the earth it became possible to prepare tracking devices which would transmit information to satellites initially these were relatively heavy the idea at that time was that there should not be more than 7% of the bird weight they were costly and then there are
Additional charges for downloading the data from the satellites so this was an expensive activity it was only RAR engaged in where there were considerable conservation issues at stake so the European stalk which at one time showed dramatic population declines over much of its range in particularly in Western Europe was an
Obvious focus of this there was also the problem that you could only use these on relatively large birds so here on the left we have an early example of tracking a stalk from its breeding site in Germany to Africa you can see the line going down as was indicated in the earlier
Diagram through the Middle East down the Nile Valley and then to Southern Africa and it’s starting to return at that point the equipment failed but later there was more success I’d like to talk briefly about a particular stalk known as princessin which in German is little
Princess this name was given to it by the local school girls and she became quite famous I met Dr cartz Who had worked on this particular project for many years at a conference and we got into conversation and his map showed that previous year princessin had spent her
Bit of her summer near a town named Mosel Bay in South Africa so I pointed out that I’d actually been born in musel Bay and he was tickled by this and photographed me next to the poster and subsequently kept me updated on her movements now we I mentioned earlier how
We have eastern and western stalks concession was an easn stalk so she followed the route you see there but her partner was a western stalk and he went to Spain in the non-breeding season so consequently he had a much shorter trip to get back to the nest side pression became a bit of
A TV personality she had been formed both in Germany at the nest and in South Africa and when when she was due back that year 2002 they sent a TV crew to the nest site to await her arrival they were rather surprised to find that clearly
Her partner had got Bor waiting for his regular mate to get back from Africa and he had a new female on the nest and a clutch of eggs had been laid so they waited in suspense to see what would happen when Princess returned turned well there was a tremendous fight the
New female was driven off the eggs were thrown out and a rather chasten male accepted back his original partner and they successfully raised the clutch of eggs again so here we can see tracking records for princess she died in 2007 her body was found with all equipment in the preate in South Africa
And it’s thought she died of natural causes there was no indication of a collision or anything else she had been tracked for 21 years at that point now the blue dots on this map show her Southward migration and you’ll see that she followed the expected route where she went out over the the
Middle East down the Nile Valley and then spent quite some time in the Sudan even drifting across the Central African Republic then headed south again spent some time moving about between Zimbabwe Botswana and Namibia and then finally headed south to South Africa so she spent significant amounts of time in a
Number of different countries where she wasn’t just in transit and and clearly this is important in terms of conservation we need to know where these migrants are going and where they are spending time and it’s become clear that individual birds follow quite a consistent route and tend to make stopovers often quite
Lengthy stopovers in the same regions which are presumably familiar to them they no good foraging areas and so on then when Frisian headed home she did this much more rapidly and directly you can see from the dates there refer to her Homeward northward migration to the
Breeding area she left South AF in South Africa on the 3rd of March by the 3rd of April she was in the Sudan and by the end of May she was back on her nest site so much more direct route and this again seems to be typical of the pattern for many migratory
Birds heading to the non-breeding areas they often make extended stopovers in different places but when heading back to their breeding sites they tend to fly more rapidly and more directly with much less stop over time another bird which is big enough to be suitable for satellite tracking is bird
Known as godwit which in southern Africa is not an especially common migrant visitor on the map down below you can see the hatched areas show the breeding range of the godwood which is right across Northern Eurasia and then into Al askan and even are close to the Canadian
Border so very wide range of tundra areas in the extreme North then the non-breeding range is in part just in Western Europe not that far but also all along the western coast particularly of Africa Red Sea and as you can see all around uh the Asian coastlines and in Australia and New
Zealand and the Australians and new zealanders were particularly interested in the migration route of this birds and more recently has been satellite tracking of this species so here we see what happens in the birds going north and you can see there were two sites in New Zealand where birds were fitted with
Appropriate packages and one in Australia and all of these birds headed north the Australian birds more or less due north and they made an extended refueling one would say stopover in the Yellow Sea region on the coast of China so this is clearly a key area for the
Species because they refuel at that point in both cases the Australian and New Zealand Birds they stop over very little before they reach the Yellow Sea region they’re flying over regions where there are islands but in many cases they’re making extended direct flights godwits are not
Able to land on water so they can only land where there is a coastline and dry well Wetlands available to them the Australian birds shown in blue then head north into Northern Siberia to their breeding areas but the birds breeding the birds coming from New Zealand are
The Alaskan population and they then fly straight across the Northern Pacific to their breeding grounds in Alaska what is much more dramatic though is when these birds fly south the godwits from Siberia again go by the Yellow Sea region and straight South to Australia the birds from Alaska however
Fly straight across the Pacific to New Zealand following these Birds by S satellite tracking has shown that some individuals will fly for 11 to 12 days nonstop because there is nowhere to land there are only a few scattered islands and these don’t have very much to offer until they reach a larger
Section of Coastline so they will cover more than 11,000 kilometers nonstop flying fairly steadily but covering about 1,000 kilomet a day and you need to get your navigation right because if you miss New Zealand the next landfall is Antarctica which is not where you want to be unless you’re a penguin and
Fairly specially equipped for conditions there certainly not if you’re a godwit so this showed that different populations can show very dramatically different patterns of migration the Yellow Sea region is important for both populations at certain times of year but for the other population only for the New Zealand population only on Southwood migration
On Northwood migration rather there’s also been some satellite tracking in Africa walberg’s Eagle is a small Eagle which comes in two color phases beautifully illustrated by this slide by wari you do find pairs which are pale phase and dark phase they don’t appear to have any particular preferences for which color phase they
Made with and this was a study done by combination of namibian and German scientists where they looked at Birds breeding in Namibia and here the pattern was of a much more rapid migration so going north the this particular bird left its nest site at the end of March in 1994
By mid April it was over it had passed the Congo River and was over Congo brazal and by the end of April so virtually five weeks since it had left Namibia it was in its non-breeding region which was Northern Cameroon Northeastern Nigeria and adjacent Chad where it’s spent its time
In quite a narrow belt it then headed south again in mid August or late August really 19th of August first date and by by the end of September again about 6 weeks travel time it was back on its nest site in Namibia where it remained for several
Months so in this case the bird was spending relatively little time at any of the stations on route and it went pretty directly following exactly the same route in a very narrow band on both Northwood and Southwood migration there are walberg’s eagles over a wide range in southern Africa we
Even had a pair who must have overshot and turned up for the first time ever in the Eastern Cape nested here for a few years then unfortunately only one Bird returned and since then that Nest site seems to have been abandoned so there we have some examples of very spectacular Journeys but
Journeys which show very different characteristics in different species so what about the smaller birds a possible technique there employs measuring day length this uses little devices called geolocators these are very small they weigh less than half a gram and consequently can be used really on very small birds they’re also much
Cheaper than a satellite tracker the downside is that you have to retrieve it to download the data these are effectively little computer chips one might call them which are recording sunrise and sunset times along the Route so you do have problems when they are flying under completely overcast conditions you may not get
Recordings on certain days and you’re then basing their location locating the bird on a map by records of day length at different latitudes this means that the location accuracy is limited it’s not as precise as GPS measurements and so on and it’s worst near the equator where day length
Differences are very small and it’s also often not good at very high latitudes but it has provided some very interesting information here we have a little 25 G bird the Eurasian whea and this has a very interesting breeding distribution as you can see on the map the brown breeding range includes
Alaska and a little bit of extreme western Canada then there are populations on Greenland and bits of Eastern Canada and then a huge range across Eurasia right across to Siberia the bearing Peninsula joining Alaska but all the records of non-breeding birds are from Africa and most of the records come from
Western and Eastern Africa it’s one which only occasionally Strays South into southern Africa so this is quite a contrast to the map for instance for the barn swallow where the North American populations head due south to South America whereas the Eurasian populations head south to Africa and
Asia so so the question arose what what are these populations doing and here geolocators were used and came up with an extraordinary result the birds from Alaska seen on the extreme east of this picture on the right hand side of the map they fly all the way across the
Bering straet and right across Eurasia most of them fetch up in Eastern Africa but the birds from Eastern Canada which is where they got a few tracked fly across the North Atlantic to the British Isles and then head you South and most of them fetch up
In West Africa a few do move to other parts of Africa now we’ve known for a long time that many migrants particularly small birds wordss which lay up stores of fat show a very marked Circ anual rhythm in their behavior and this means that if you’re keeping these birds in a
Laboratory under constant conditions they show periods of what is referred to as migratory restlessness or tunua the German term is often used in the literature at appropriate times of year and they also go through a phase of laying up great loads of body fat prior to migration so their whole physiology
Changes they eat extra and store it as fat some small birds actually double their body mass before they leave small birds can actually do this they can carry very large amounts proportionately of extra weight whereas large birds can’t so Eagles can’t fly off with small children
Uh the prey is too heavy they can kill quite large prey including small antelope in many cases but they can’t carry these off that’s just a sideline so if you put Canadian birds and Alaskan birds in the laboratory and then observe them over their annual cycle you find that the
Canadian Birds go through a pH days where they will fatten up in preparation for migration but the Alaskan birds don’t so there’s a basic physiological inherited physiological difference between these populations the Alaskan birds are flying over land effectively all the way except for very short sea Crossing so they’re feeding as they go
Whereas the birds which are crossing the North Atlantic have to lay in supplies for the sea Crossing here’s another example this is a little bird which I came across an interesting paper on it and I’ve never actually seen it but it really does look like something which uh a child was asked to
Illustrate and given a pot of paints and they try to put as many colors as possible on the bird very beautiful little seed eating bird and as you can see very small bird now in North America there are two breeding populations eastern and western the Western population is the
Larger the Eastern population is in trouble from a conservation point of view because the areas where the birds breed are along the eastern coast which is heavily populated lots of habitat change and they’re then flying south to Florida where you can see the brown areas on the right hand side of the
Screen where some of them drift into the Caribbean but these are also areas where major habitat changes and so on are underway so the Eastern population is declining yeah geolocators were again used and these showed very clearly that two populations move in quite different ways and there appears to be absolutely
Minimal interchange between the two areas which is also supported by ringing daughter so looking at the Western population the birds from Arkansas seem to head more or less due south along the Gulf of Mexico and then fetch up in the breeding areas the non-breeding areas along the yakatan
Peninsula um from southern Mexico into adjoining countries Honduras and so on but the birds from a bit further west from Oklahoma will fly to Northern Mexico and there they hit a favorable period if they get their timing right of monsoon rainfall where there’s lots of food for them they undergo complete mol
At this point so they replace all of their plumage so have an extended stopover before they then head Southeast to the main non-breeding area so once again the important areas are in this case the breeding areas for some of the population this molting area in northern Mexico where they have an extended
Stopover and then the non-breeding areas over a much wider range and along the peninsula they were quite lucky here they used 500 geolocators so that’s still a considerable outlay I can’t resist showing another picture of this extraordinarily colored bird and they recovered a quarter of
Them which is is quite good going I read of a very sad study in Germany where a small warbler they had identified a population where there was very high return rate of birds to their breeding site and they decided this would be a good population to use geolocators on they used 100
Geolocators and they retrieved three so a very poor result from which you can’t make any very convincing deductions now this story of the Woodland king fisher involves War Teton very directly this pair of Woodland King Fishers had nested for several years in a nesting log outside his Cottage in a
Place now known as Modi moly in South Africa shown on the map the coloring used on this map is unfortunately not not very distinctive but the interesting facet here was that the male and female were marked with geolocators and they both came back the following year to their nesting log the
Geolocators were retrieved the data downloaded and it was shown that they had both flown more or less due north but the male had gone to the South Sudan and the female to the Central African Republic so although these birds were a pair who had bred together for several
Years and came back to breed together again they didn’t spend the non-breeding period in the same area at all and appear to have moved quite independently while on migration now a little detour to consider how birds find their way they don’t of course have access to maps and navigation
Systems although the cartoon there of the homing pigeon studying a road map does show that when homing pigeons were followed in the UK they found that many of them actually didn’t fly in a straight line to get back to their home Roost poop they actually followed the roads so they were using
Convenient visual cues we need to distinguish between two terms here one is orientation orientation means just determining a Direction You orientate towards the sound to actually navigate you need to plan a route from A to B and this requires a map and a compass so you need to be able to
Determine where you are where you’re heading and plot an appropriate route so what cues might Birds use because Sailors have for a long time Ed sightings the seon for instance of sun and stars to determine their position this was the first focus in looking at how migrants might
Find their way now quite a lot of the early research was done using homing pigeons because they’re readily available and well known but of course homing pigeons are not true migrants but it emerged that yes they can use sun and stars for their basic orientation but they can’t use them to
Navigate they although they make allarm for changes in time of day the position of the sun and stars they don’t use this in a way that enables them to determine their position on a map so they lack the essential element which is a very accurate clock which was a key in human
Navigation at se so people wondered do birds use magnetic fields and this is to me always a particularly interesting example of the way in which science sometimes fumbles along and often needs a new approach new equipment new techniques to find the right answer in the 1940s there were
Some tests done on homing pigeons and they were tested in strong magnetic fields the thinking being well the Earth’s magnetic field is a weak field if birds can detect weak magnetic fields you should get a much clearer response to a strong magnetic field thinking of how human instruments would
React and they got no response so the conclusion drawn was well they don’t detect magnetic field so we’ll go on and look at something else uh one of my favorite books is a book called the Haka guide the Galaxy which I hope many people have read it’s
A sort of laugh art aloud book there are many passages which are hilarious ridiculous and improbable in the extreme but there’s a famous section there where the great comp computer is asked to answer the question solve the mystery of life the universe and everything and at the
Appointed time they report to the great computer which replies 42 and everyone is app ped and says but what use is that to us and the computer replies perhaps you should have thought more carefully about the question and this is often the case in science one should think carefully about
The question so the question actually posed here was do pigeons detect strong magnetic fields and the answer was no they do not detect strong magnetic fields but the question hadn’t been asked do they detect Earth strength magnetic fields so some years later the European Robin was studied and there are populations which
Are migratory they’re able to show very conclusively that these migrants altered their orientation in Earth strength magnetic fields when North and South for instance were reversed they then flew in the opposite direction in a laboratory situation where they didn’t have access to Sun or stars and this was the only cue available to
Them they then had a look at pigeons again and did the obvious experiment where they sent pigeons out with little brass metal collars or magnets attached to them and they found very interesting phenomenon that the birds with little brass non-magnetic colors they orientated just as well sunny days and overcast days they were
Unaffected the birds with magnets attached to them became were fine under sunny conditions but became as the bottom diagram shows completely confused under overclass conditions so when they didn’t have the sun available to them they had to switch to Magnetic orientation and then the magnet interfered with the system
The question then was how do birds actually detect magnetic fields and they found some magnetite little iron crystals in the beak of the pigeon they thought oh well that’s the answer and then over the years they tested a number of different small birds which could be conveniently tested in the laboratory
Here we see some examples from North America from Europe and from Australia all of which proved to orientate in the same way and presumably using the same equipment but then some experiments with the silver eye little Australian bird better known as a white eye to many of
Us showed that under red light these birds became disorientated and they suddenly asked the question well why does light affect magnetic orientation and then earlier there had been some suggestions from theoretical physics and chemistry that photopigments might be affected by magnetic fields then they looked again also at
The pigeon bits of magnetite and realized these weren’t connected with the nervous system in any way that suggested they were providing useful information so they went back to the visual system this went back quite a long way 1978 theoretical physicists had written a paper suggesting that the pigments in
The visual system could be affected by light energy and they proposed what they called The Radical pair hypothesis that two different states were possible and the Magnetic forces would determine which state was established in these pigments and it was all based on some highly mathematical calculations sort of
Things which might frighten off um the average biologist so even though the paper was intitled ways in which the title indicat way in which living organisms might detect magnetic fields it probably wasn’t taken very seriously by most biologists who didn’t read it because it’s in the wrong place there
Was no biological evidence people questioned the sources and there’s this famous idea in science known as oam’s razor where they say you should select the simpler explanation rather than the more complex one so everyone went for something easier this amusing illustration by one of the people involved in these studies simply pointed
Out that if you’re dealing with an unstable system uh fly for instance Landing on a a block which is tilted could affect so small energy impact could well have a dramatic effect and here we have one of the people who is written very extensively and whose writings I could recommend to
Anyone who wants to follow up on this area H mortson he’s a Dane who’s currently working in Germany and he went to a new took up a new Post in Germany having worked elsewhere and he had a research station these little wooden huts and they were testing once again European robins and
They found that magnetic orientation these birds was being completely confused and they realized after some tests that this was due to a radio station which was not too far away in the town so radio waves which of course are electri magnetic radiation on the same Spectrum ultimately as light and other
Things that these were affecting the behavior of these robins and only once they insulated these Huts did they have no interference with their experiments by this time investigations of the nervous system of birds had progressed to level where it’s possible to record in very fine detail in live Birds without damaging
Them in well you do have to apply a little very fine electrode but the bird is not being seriously injured or inconvenience because brain tissue itself doesn’t feel pain so you can record from individual nerve fibers and they found an area which is rather un imagina labeled cluster
N and the input of cluster n comes in from the optic nerve from the ey and you can both chemically and electrically disrupt nervous input to particular centers only temporally and you find that if you do that if you vent input to Cluster n your magnetic orientation Falls away they can
Still use the star Compass or the sun Compass so you’re not knocking out that side of the visual system but if cluster in is not receiving information magnetic orientation falls out they’re also working in collaboration with colleagues in Russia who working with European re Warblers the first population they were
Working with was just near Moscow these birds would be flying towards Northern Scandinavia which was their breeding area so they then moved these birds thousand kilometers to the East and clearly to get to their breeding areas they would now need to correct for this displacement and they wondered would
They be able to do this and sure enough they were and after quite a lot of work they found that there is another magnetic system which is responding using information on this East West displacement so a map system the input comes from a different nerve and different brain areas are
Involved if you disrupt the input on this trial nerve magnetic compass works so North South directions the sun compass works the star compass works but they don’t make this adjustment for East West displacement and this is still an ongoing area so anyone can follow up on this and
Sure enough in the European Robin has just a diagram of an eye which you can see in any doctor’s surgery showing the input of light and they found that there is an appropriate protein which is most abundant in the migration season and is found in the cones in the retina of
Robins so just to recap about the magnetic field 1944 you had experiments with strong magnetic fields and the results were negative and temporally they concl scientists concluded that birds weren’t using magnetic information 1965 experiments with Earth strength magnetic fields included oh actually they are in 1978 this radical pair mechanism was
Suggested by theoretical physicists the idea that phop pigments would be modified by magnet but in 79 they found magnetite in the beak of pigeons and thought oh well this is probably the sense area but in 1993 it showed that light of different wavelengths influences magnetic orientation then synthetic Chemists in
The laboratory showed that photopigments do indeed respond to Magnetic effects in the way that the these physicists had predicted 30 years previously and then re-examining the beaks of pigeons they realized that these iron crystals there were unrelated to magnetic field detection there was no no nervous input then they found again that low
Power radio waves disrupt magnetic orientation and they were then able to demonstrate that photopigments found in birds are actually responding the way the physicists and the chemists had predicted but then a little later they found the second system for longitudinal displacement East West displacement which is is still under study
So new ideas new theories things which are neglected and then become relevant and a very long and convoluted story now just last year seem to be going a little over time here I hope everyone has a drink in hand and time to listen there was a review in a journal called
Orthological applications by main lead author was ion so you can find this online if you want to and they were looking at global positioning system GPS uh as opposed to what they call platform transmitter tags PT they looked at a series of birds less than 500 GRS which were
Not available for the usual were not subject of the usual um satellite transmitter sets they found 92 studies which met all their requirements notice only four of these in Africa and only seven were in the southern hemisphere the other three were in Australia they then looked at the success
Rate GPS where the actual tag was recording the information you had to get it back these are very small tags they can be one gr or but the in the retrieval rate is less than 20% so not a very good outcome where the GPS tag is transmitting now this can be transmitted
To cell phone Towes other fixed stations on land there was a much better success rate but this is restricted to areas where you’ve got enough receivers so where you’ve got good cell phone coverage you can can use cell phone tows but naturally many of these birds are moving over areas
Where receivers are not necessarily available so you’re going to have lots of gaps the best results were from the trans platform transmitter tags which are sending the signal to the satellite and it then has to be retrieved from there the platform transmitter tags are becoming quite small but there are
Extras in terms of sometimes solar panels and so on and an Tenny so they are still not entirely suited to very small birds and particularly because they are arguing on the basis of comparative studies that the limit should be around 3% less than 3% of the bird’s body mass
Now let’s just have a quick look at two spectacular examples which one of which is Southern African one of which I acquired from this paper Australian banded STL is one of these waders that nests in very arid areas they had platform transmitter tags 5 G which were fitted to a 300 G
Bird these birds nest in the most arid areas of our Australia the redder the rainfall is highly variable and unpredictable and it’s also very dry they found that over a period of three days one bird moved over 2,000 kilometers and you can see they are moving from coastal areas out into
Central Australia to areas where rain has fallen and suddenly breeding opportunities become available so very interesting situation the flamingos in Africa we have some ringing daughter which for a long time LED people to conclude that with the greater flamingo in the upper picture which has a pale
Ball and dark tip below is the Lesser Flamingo which has a dark red uniform dark red B is a slightly smaller bird great flamingos were thought to have three main areas in Africa East Africa number three West Africa number two one is the northern population and Southern
African and it was thought that there was probably relatively little interchange between these lesser Flamingo has populations in a more restricted area through eastern and southern Africa along the coast of West Africa and also population in India we had some indic ation from ringing results that there is actually interchange between these
Populations but much more interesting data became available from satellite tracking Lessa flamingos these birds were marked in southern Africa in South Africa and one bird in particular flew almost immediately to mosm Beek so flew East and then went to Madagascar and spent two years on Madagascar so this
Confirmed what we have long suspected about flamingos that they don’t necessarily breed every year that they have may have long intervals between breeding episodes and you can see there are very extensive movements through southern Africa from this another bird which has been examined is the black Harrier which is very much a
South African endemic there’s a small breeding population up in Namibia the reddish points on the map here indicate areas where the first bird Atlas which was concluded in 1995 um showed the birds to be present much more often than the current bird Atlas which started around 2003 so suggesting that there’s a population
Decline so once again GPS tags here using fixed stations like cell phone tars were imployed we found a wide variety of patterns some birds remained in the west coast area which is where birds were caught and marked at their breeding sites but a number of them moved very far east past lutu
Into quaz Nal and other areas there so not only are they exposed to potential problems around their breeding sites where habitat change fir because they’re ground nesting Birds the wrong time and wind farms are a problem they’re also exposed to wind farm areas which are being established
In many other sectors of the country so once again from conservation point of view knowing where these birds are going at different times of year and how to best try to assist these populations is a major factor so let’s think about what will happen in the next few years uh
Naturally technology is advancing all the time tracking devices to actually follow from daytoday small birds will undoubtedly be readily available in the next generation of biolet for the next generation of biologists then there’s a question of climate change can birds adapt will they be able to modify the timing of
Migration breeding to match what is happening to the habitats that they are using will some population stop migrating that is also a possibility if conditions become uniformly warmer Birds who stay at home will actually come to outnumber those who are traveling and which birds will go extinct
For me tracking devices to follow the sort of small birds I’ve worked with would be fascinating we for instance would be very interested to know what swallows do on a day-to-day basis on migration and the little bird down there is an example of a that’s a Wood Thrush a window
Casualty which is one of the factors which has an impact on many birds obstructions which we have put up in their environment and which affect them in different ways and cause high mortality are a very important element in population changes so I hope that I’ve thrown out a few
Novel stories there which you can follow up for yourselves and if we have any time I’ll be happy to try to answer any questions thank you thanks Adrian that was extremely interesting I’m going to definitely look up some of those leads that you posted here um your first question from Chris
How do godwits fuel their extended FL to New Zealand well they they do lay up fat fat is very good fuel so these birds do lay up very heavy fat stores and what we found for most birds where they’ve looked at the speed of flight is that there is a particular
Speed of flight where the bird will be be most comfortable and will be using least energy and that in fact seems to be the speed of flight that migrants typically use so they they’re not going too fast or too slow obviously they want to go fast enough to cover the distance
Within their their fuel range and they do seem to settle into uh the most economical speed they some birds also but I’m not sure that godwood do this some birds also fly temporally high so they can use the jet stream at high altitudes the downside of that is
That oxygen is less readily available at high altitudes so they tend to do this for brief periods and then drop down to lower levels again thanks Adrian okay your next one uh from Lawrence it’s quite a long one one of the South African roosting sites for bar
Swallows is at Mount Morland close to King Shaka International Airport over 10 years ago I installed Some Noise monitoring equipment at Mount Morland and 18 other sites which was intended to keep track of aircraft air aircraft noise but also to study the impact of aircraft on the migratory Birds does
Adrien have any daughter to reflect a reduction of the barn swallow since King Shaka international airport or the impact of environmental noise and pollution on the migratory patterns I I don’t I do know that birds are are affected by environmental noise an area that I have followed a little is
The question of urban birds actually modifying the times that they sing and even the frequency of song in relation to the noise environment that they experience so they certainly react to that with barn swallows there have been changes in the root sites that are used so that they certainly do shift Roost
Sites for reasons which are not always obvious to us thanks and Lawrence also asks has any concrete evidence been found regarding effects from 5G and 10A on Birds no we as I say the evidence that that electromagnetic radiation of various types like radio waves and so on does affect their orientation systems
But this is quite localized and we’ve known in the past that there are for instance magnetic anomalies surrounding large or deposits so there are geographical sites where migration orientation is also disrupted by these but fortunately that seems to be quite a local effect the general pattern with
Orientation seems to be that they use visual cues as far as possible and the Magnetic system is used to establish their initial responses to the visual cues and then used as a backup when visual cues may not be available that’s interesting and then Colin asks Birds obviously lose water through
Respiration how do longdistance nonstop migrants deal with this well a lot of them migrate at night and particularly in the case of migrants in Africa coming south from Europe when they’re flying over the Sahara they migrate at night and if they’ve lost too much water they all haven’t got enough
Fuel they stop over at oases in the Sahara and spend periods resting in the shade and refueling before they continue so yes it’s it’s it’s a very real factor for them and they can be quite severely affected by bad weather conditions sort of Wind Drift which may carry them out too far
And then they are losing losing water at at too greater rate okay and Angela says what was the German word for migr migratory restlessness ohua it’s z g u n r u h e and it is a word you’ll often find in the in the literature
Now okay and Peter asks which bird does the longest annual migration uh conventionally that’s considered to be the Arctic turn yeah because many of them breed well north of the arctic circle and a large part of the population then spends their non-breeding season South of the Antarctic Circle so they are reckoned to
Do about 20,000 k a year okay um Mark bridgeford said Bartel godwits for about seven years our summer quack counts indicate that numbers in plate have gone from five Birds to well over I think that’s a 100 this year can you suggest just any reason for this dramatic increase in these migratory
Birds these are bartail God withs at PL at PL yeah from five to 100 over 100 yeah there are shifts in in populations I know with the cly sandpipers it was shown many years ago that their populations visiting South Africa were very dependent on things like liming Cycles in their Siberian breeding
Grounds so when there are lots of lemmings the Predators like thetic foxes don’t uh don’t eat as many ground nesting bird eggs as in other years so when Lemmings are in short supply many nests are destroyed by the groundbased Predators but I don’t know with the godwords it would be very interesting to
Know which population these represent whether it’s a shift from birds from other areas that are starting to visit southern Africa rather than a previous stopover point but uh I really there may be people in Europe Who would know the answer to that yeah that’s fascinating that um dramatic increase in
Numbers okay Angela says the idea that pigeons use roads was very interesting would something like this have evolved with Humanity since we’ve been making paths and constructing roads for thousands of years also do we know of any other human-made markers that birds use for navigation well they certainly use lots
Of visual lose particularly over short distances so homing pigeons are typically flown over areas close to their to their home coups and they certainly are using mainly visual markers under under those conditions so they would be using any kind of landmarks both Rivers streets uh buildings even they probably
Use conspicuous towers and so on and mountains valleys not only geographical features but also definitely things that we’ve added to the landscape yeah what absolutely astounds me is how a small little swallow can come back come back to the exact same Garden to the exact same nest that
It um nested in last year you know that the GPS the navigation systems are so excellent well I think the navigation system gets it to the general area and I think then it homes in by simple visual cues for for the last bit of it so and
Also memory it must remember you know from last year where it was and yeah okay Colin who asked about the godwits and the water he’s saying um those long um migrations from Alaska to New Zealand where they don’t stop over and drink water um I think you said it it spent 11
Days in the air nonstop migration so um is it true that they their body organs sort of um eat themselves as it were during migration and then they to feed up again we know that for summer some of the other waiters I’m not sure if it’s been
Demonstrated for the godwit but I know for some of the waiters from Europe before they depart the gut actually shrinks it reduces quite dramatically in length and this reduces their body weight and then the gut regrows when they stop and start feeding again so yeah there are in some cases at least
Major physiological changes and we know from hibernating animals that they’re able to reduce oxygen blood flow and so on input to particular areas of the body so they maintain the crucial areas and effectively neglect other areas temporally just keep them at ticking over level as it were and I’m sure that
This physiologically is happening during migration that key key areas respiration and blood flow to the muscles are being prioritized as opposed to blood flow to many of the internal organs and so on yeah and they also shut off half their brain and sleep you know they have like
Catnaps yes um if anyone wants to read a really fascinating book about bird migration there’s one called A World on the Wing by Scott beeden saw it’s a new book that I’d got at my local Bookshop I just couldn’t put it down it was so extremely interesting I’ve written it
Here in the comments if you if anyone wants to try and find it okay the next question Peter asks do Arctic turns fly nonstop which species flies the EST nonstop the the longest non-stop flights we know of are definitely the god Woods because the Artic turns can land on
Water and they are quite they don’t fly along the open ocean they do hug the coastline so they are feeding in coastal Waters as they go along so they are certainly stopping quite frequently yeah I’ve seen arctic turns at Cape receip so they they do stop over um on their way down to
Antarctica okay Elizabeth asks do you have any information about how the war in Ukraine is affecting migration of European species all the bombing and all that well I think birds birds would avoid areas where there’s lot of disruption and also air pollution obviously from the the bombing they would make small deviations which
I’m sure they can accommodate I don’t think there are any major stopover areas there because that’s quite early in the in the migratory system but many years ago over Israel the Israelis actually had a big project investigating migration because you do get concentrations of large birds things
Like Pelicans Eagles and so on passing over and this is important both for commercial and military aircraft so there there has been in the Middle East a very for a number of years very good monitoring system of major pulses of migration through the region to and then informing aircraft of
The altitudes at which these birds are flying so they can be redirected to to avoid them um talking about Israel there’s a bombing there as well at the moment and it’s quite an important migratory rout K Rosie asks have you seen any evidence of migratory Birds anticipating changing weather patterns to avoid um
I’ve got something over here hang on I’ve got something over there to avoid indeed use weather to Aid migration they they certainly do they do take advantage for instance of wind conditions so favorable winds to help them so if they you’d obviously want a Tailwind in those circumstances and
That’s they they certainly make use of that or will stop off and stay over under unfavorable conditions but they’re not they’re not always successful they’re are many records of birds landing on ships out at Sea which suggests that groups have got driven seriously off course and that the ones
Who landed on the ship are are the lucky ones that the others have already come to grief so bad weather conditions can be quite disastrous for migratory populations uh Lawrence your comment about the rose ringed parakeet they’re not migrants they were introduced they were escapes from a probably from a cage
And they’ve the population’s built up so yeah they’re not migrants um okay last one Rosie says there was some work being done suggesting that sexual organs diminished in Readiness for migration to non-breathing areas not being required and aiding weight to a migratory bird fascinating idea has Adrian heard about this
Research oh that that that’s that’s very common in seasonal breeding birds for instance our local Cape Weavers the testes in a male will be about 12 mm long in the non-breeding in the breeding season and they will shrink to a diameter about 1 mm a few months
Later so yes that happens in migrants but also in many many other seasonal breeding birds and the same the same pattern in the female males that actually in the non-breeding season if you are examining one of these birds a road kill or anything you may find it
Quite difficult to be able to identify the sex organs oh that’s fascinating yeah that’s the end of the questions um Adrian that was really fascinating thanks so much um there lot of people saying thank you for your talk it was absolutely fascinating I’ve learned so much thanks Adrien thanks everyone for
Attending yeah we we hope to get you back to talk on some other topic again Adrian well be available sure good okay thank you everybody bye