|Titre||La migration des oiseaux|
|Dernière mise à jour||04 January 2010|
The migraton of birds
We have seen a lot of linnets, quite a few meadow pipits, some spring wagtails, we were lucky and saw a small peregrine falcon late this morning, so that was fine, and yes that's about all this morning, some swallows too but it was the end of the wave, so that's really only a few. In general the birds, we count them when we are sure that they are passing over the water, in general when they are passing over the water they don't turn back, it is truly that they have the urge to migrate. There is no doubt about the fact that they are not going to turn and do a big circle. There, that's a group of sparrows, but they don't migrate, they are resident, they stay here.
At the start of each autumn, if you come at dawn to Aiguillon Point, opposite La Rochelle. You will find a handful of men and women equipped with binoculars and telescopes observing meticulously and with wonder, the passing of the migrating birds.
They are there because it is a privileged place as Lucien Grillet tells us.
It is only the passerines that we watch, the passerines, - the little birds that look like a sparrow. The passerines come from the north of Europe, from the north and from the east of Europe and they migrate towards Spain and Africa by following the coast. So why here? This is the place where the sea is narrowest; the branch of the sea is least wide. This point goes into the sea and opposite there is a similarl point which goes to the north. So the birds, these birds don't like crossing big stretches of sea. They prefer seeing the land when they are going south. So that's why it's been noticed that the birds concentrate here, the birds coming from the north concentrate while going south. Perhaps it is easier to find the way while going along the coast, perhaps, but in the end we don't know. We have noticed that the coastal strip, that's the place where we see most migrating ones. Some come from the very north of Europe, from the north of Norway, from all of Scandinavia, from the British Isles a bit, and then from the east, from the east of Europe, from Poland, Germany, going towards the south-west, so they arrive here to fly together towards the south of France, right, the south west of France.
It is not especially the temperature which stops them from spending the winter here, as we have a quite clement temperature, but the shortage of food. Insects and especially seeds. Already the birds which live in the north of Europe can no longer live there in winter because, right away it is dark up there and then with the ice and the snow the ground is covered, so the seeds are inaccessible, the insects are all right but the seeds are in accessible. So why do they not stop here since there is certainly quite a lot of vegetation and there is never any snow? Well the mass of birds which arrives from the north would be much too many to find enough to feed itself, so it is forced to fly further. Some stop; but the majority leaves for Spain and Africa, no doubt about it.
Lucien is here for pleasure - he has been watching the migrations now for 60 years. Although a member of the League from the Protection of Birds, his observations and those of his colleagues also have a scientific goal.
So, that's... ten years that we've been doing it, we've been conducting this study. So the interest naturally is to have the knowledge about the period of migration of difference species and then especially for a few years the variation of the population. And unfortunately we have noted that some populations are down considerably. The linnet, for example, we started counting in 1993. And in 1993, a good year for migration, we counted here 132,000 linnets which passed over. And in 2002, 40,000. That is an enormous fall. And at the same time as that, there are methods to count the birds in spring, this study has taken place all over Europe and all Europe has observed a clear reduction in linnets. We estimate 45% fall in the population.
For him, there is no mystery about the cause:
Agricultural practices. With the disappearance of insects for the swallows, and the disappearance of the weeds which the linnets fed themselves on. With the use of herbicides, there is a pile of weeds which have been disappearing, which have been becoming quite rare and it is really the seeds of these plants which feed these birds.
And for the ornithological richness of the area, the consequences are very serious:
I think that the swallows are going to disappear. Because there aren't any more insects, there are very few insects. You can see the evidence for example on the windscreens of our cars, it used to be that when I drove far, I had to clean the windscreen every day because there were insects stuck on it, now I still drive quite a lot and I clean it about once per month. Well that's the evidence that there aren't any more insects and the swallows are suffering a lot from this state of affairs. Each female swallow lays five eggs; once five eggs, five chicks, five little ones fly off; today five eggs, five little ones hatch, and two fly off. Instead of doing several clutches as in other times, the swallows used to do two or three clutches. Today there is one or two clutches, but never three. Because there is not enough to eat, the swallows don't have enough energy to lay a second or a third time. The reduction is catastrophic and here people from all over note that 30 years ago they used to see the swallows concentrating before the migration. We used to see flocks of several tens of thousands of them and now instead of seeing a few thousand of them, there's fifty or a hundred, and so it is a species which is going to disappear probably from our area.
The LPO (League for the Protection of Birds) is fighting for changes in agricultural practices but without any real hope of winning their case.
Well, we would welcome a return to a reasonable use of herbicides, preferable biological herbicides and practices, biological ways of using them avoiding the use of herbicides and insecticides. We can write about it, that's all, but our weight is very small.
Not all of the birds are suffering. For the sea birds the trend is the opposite:
You have the gulls - the sea gulls all these sea birds, you have a bird called the cormorant which is multiplying in a remarkable way. Why? Because for about twenty years there are a lot of fish farms everywhere. So the cormorants eat the fish. Thirty years ago the cormorants used to migrate to Africa. About thirty years ago, when they got started, they organised fish farms everywhere in Europe, everywhere, everywhere, everywhere, the farmers in particular dug pools for irrigation, they took advantage of them and put fish into them. So the cormorants saw that there were plenty of fish so they stopped migrating. So migration entailed a lot of mortalities, a lot of winter deaths. So for thirty years now there is no more winter death. So there you are, they multiply and it is not because they are protected because in other times, they were not protected, but that's how the population started to grow. Now they are protected and the fishermen say: "it is because they are protected". No. It is because they are living well. They are really multiplying. And the gulls are the same, the gulls live on household waste, and for twenty years the waste has grown everywhere, so the gulls are doing well.
The concerns for the future do not spoil the pleasure of the moment however. At Aiguillon Point, you can see tens of thousands of birds getting ready for the journey to the south. They repeat again and again a beating chorus whose origin is survival instinct.
They flock together for one reason... mainly for safety. The birds are always afraid of predators; whilst predators only take away a few of them, in the end it's an inherited fear and a big flock of birds is less susceptible to predators than a bird on its own. Whilst the flock of birds is quite compact, there's always one or two who escape, who get away from the group; if a predator is following it, a hawk or a falcon, these are the two, they'll get it and not the tight group. You must know that in a flock every bird does the same thing as the one ahead, but it is not exactly the same. We see that in flight. The starlings for example. In a flock of starlings you have this flock of starlings which makes circles in the sky which makes big... well the first goes this way, the second follows the first, the third etc, but there isn't a leader.
There is also the pleasure of hearing the bird-song:
The birds have many ways to communicate. There is singing, right away, the passerine, the mating song which is the call, the male sings; right away it is only the males who sing. So the male sings to attract the female and also to mark out his territory. From the moment that a bird sits on this post and sings that means that the territory around this post is his and that other males do not have the right to come in. That's one thing, that's the song. There is the rallying cry. So the birds in flight make a little cry to the others who are in the flock, not to get too far away from one another. There is the alarm call, when birds are at ease, if a predator appears a bird of prey or a hunter, the birds give out an alarm cry and everyone takes off. An alarm cry by the way includes other species. One species raises the alarm but the other species understand the alarm cry and leave too.
The migration season lasts three months:
So, I am going to take it in chronological order, because each species migrates at a definite time. We start in the month of September, seeing the swallows going, well spread out, and the wagtails, spring wagtails, then we have the linnets, at the moment, it's the song linnets which are on their way, next it will be the meadow pipits, the meadow pipits are very Nordic when they arrive, some even come from Iceland, you see, there are many of them that come from the north of Norway. So these birds will be passing here from the beginning of the month of October. Then it will be the goldfinches, then the chaffinches, tree finches and then the linnets and at the end, the thrushes, thrushes, which too, the thrushes come from the very top of Europe, so the very north of Scandinavia, and the Baltic states, even Siberia.
For Lucien and his friends, the observation of the migrations is carried out very enthusiastically.
From the start, it is a pleasure which I've had for a very long time. For more than sixty years. Then I've always loved watching the birds here, for me the migration is a quite extraordinary phenomenon which I love coming to see. You see thee birds leaving for far away which come back from far away to the same places as when the birds leave to winter in Africa, when they come back to reproduce, they reproduce in the same places. Each individual bird finds his place, so I find that, it's magic.
$Id: 2003_10_act.htm 69 2010-01-03 22:00:00Z csshab $
With questions or for more information, please contact Alistair Mills (firstname.lastname@example.org)
Updated 04 January 2010