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A good ear, a good pigeon !

Posted on 06/02/2018, Author: HG/Phil


 

We never know enough about our birds. So let us look at this interesting new study that American biologists carry out. For 10 years these ornithologists have been working on this and they are still doing further research. They want to learn more about the ability of birds to detect barometric variations.

The integrated barometer

Several previous studies have already shown a change in attitude in some birds, including the pigeon, with significant barometric differences such as thunderstorm, storm, heat wave, etc. In the hope of better identifying and understanding these behavioral changes, two American biologists spent the past two years studying this phenomenon.

In order to carry out their research properly, they first had to ring different types of birds and chipping from songbirds to large seabirds to dozens of others, migratory birds or not. They also found many testimonies from people who lived in areas with severe weather: hurricanes, cyclones and even tsunamis. These extreme events have caused a very significant change in behavior in some animals, while others have not been affected, except that they have fallen victim.

From the collection of evidence it became clear that within the birds themselves the reactions were very different, depending on the species and ecosystems.

Let's keep it simple and see what happens at the arrival of a cyclone or a hurricane.

- Birds living in the trees seek shelter. They hook themselves firmly to a branch. They can easily stick to a branch in very strong winds thanks to the ability to close their toes, tenfold by the automatic compression of their tendons. They remain passive during the storm. We understand hereby that they just wait and see what will happen. They only come out of their sheltered place when the storm is over. At least for those who have been able to offer resistance. For letting go of the branch in such a strong wind is equivalent to a certain death.

 

- Seabirds are hit hard. Some species do not detect the storm and are confronted with it. Some birds were more than 500 kilometers away from their place of residence. Many died of exhaustion. One species in particular has shown that it can detect strong atmospheric pressure changes: The Jan-van-Gent. Birds that had a microchip and transmitters acted the same way as Hurricane Sandy approached the shore where they lived. They fled, followed the coast to the south and then turned to the open sea. The goal: to get around the hurricane, to find out. Then they made the opposite way, from a distance following the hurricane that was exhausted, to nestle themselves on their rock again. Pigeons are very sensitive to barometric variations. All studies have shown that they can detect them. But that ability differs according to various factors: important development or not of the middle ear, the feed, the state of the form, the time of day. Tests on adult pigeons showed a greater detection capacity when tested under artificial conditions.

 

Not all at the same time …

As we have just read, scientists have  shown that pigeons can detect barometric variations. We also know that it is due to an organ of the middle ear, an organ that we humans do not have. It is called the paratympanic organ. That is the internal barometer of our pigeons. Also many species of aquatic birds (and sea) have it. Because it serves just as well to detect the differences in air pressure. Do not dissect your pigeon to find this! It is located in the eardrum cavity and connects the eardrum with everything that forms the inner ear. It is bathed in a liquid to communicate faster the information that is detected by thousands of micro-cells on the wall. In short, these cells activate and transmit all information directly to the brain. Some of these cells are also found in people for whom they serve primarily for balance.

But let us go back to the pigeons! They all have this organ but yet they are not equal Some will develop more than others the possibilities of this paratympic organ. It is the liquid that makes the difference. He does indeed send ALL information during the flight: it is therefore a barometer and an altimeter, but also a rudder. The American study shows that the carrier pigeon can respond to a change of 10 mm, the equivalent of a difference in height of 10 meters. In Formula 1 we would call that a fantastic help in piloting. By detecting such small pressure variations, the pigeon immediately adjusts its flight. The role of the spinal cord is also crucial. As with all vertebrates, it ensures a good transfer between each organ and the brain. The studies have shown that a pigeon, if he survives a shock (predator, electric wire, obstacle), can be far less effective in his detection capabilities because of the non-visible damage of  the middle ear and the internal damage. The state of form is inevitably also important. A developed paratympic organ in combination with a state of optimal form, this is what distinguishes the 'top birds' of others, so that a pigeon follows the one course rather than the other because it has detected the storm that occurs, the corridor where the pressure will be the most favorable.

Let's not forget an essential factor in competitions: the mass effect. A group instinct is so strong in the pigeon that he comes to follow the others on each flight. Sure, he returns to the herd but he follows. During the races, the 'followers' no longer develop their own detection capacity. This explains why some "followers" often belong to the victims when their form is less. At that moment, unloaded by the platoon and self-appointed, his detection ability will no longer enable him to detect and anticipate. Either he flies lost, or simply follows another pigeon and falls somewhere in antoher colony, or he comes home only days later. For the latter, rest, care and no more flights until the form is up to standard again. Yet this will not be enough for a few ...

Also the role played by food should not be neglected: your champion must be able to handle the distance. The heavier the flight, the more energy he will need.

 

HOME SWEET HOME

Also an important factor during the races: the wind is the friend of the champions. Especially in the mouth. The body we are talking about is also capable of detecting the increase in wind speed and the increase or decrease in precipitation. In the face of extreme weather conditions, the pigeon can not do everything. Your champion is driven to go home. Nobody has a scientific explanation to date. However, it is this natural instinct that takes precedence over everything else. Certainly, he detects a meteorological difficulty, but he will make the choice of how best to confront him, because he wants to find his hen, his box, his home sweet home. Nothing is easy, despite such possibilities to anticipate events: the direction of the wind, this inexorable attraction of the loft, the crowd, the pigeon has to instinctively juggle with all these elements. We should not forget that for the long distance fatigue will strongly influence the natural capacities. However, it is precisely at these great distances that most metereological changes will occur and it is therefore important to deal with them. With how many changes does the pigeon has to cope during the flight from Barcelona to the loft? When you see that it sometimes rains with you continuously and is 4 degrees colder than with your friend who lives 5 km away and it is sunny there, imagine a 1000 kilometer race!

A concrete example is the Barcelona of 2017. When unloading already 22 ° in Catalonia (9h05 is too late !!) Between land and sea the start of the flight is easy to manage for the wind (west) less for the altitude. Some will circumvent the Pyrenean massif and others dare to fly over it. The biggest danger (but that applies to the whole flight), are the predators ... Then to the contours of the central massif. Between the coast and the first reliefs the changes in condition (wind, temperatures) are legion. The Rhône is lower, but it does not cool off the pigeons who, from leaving the massif, have to face a heat wave and still have hundreds of kilometers to go. The heat wave is an enemy. Stormy fronts pop up everywhere. The map of the storms on July 7 shows it: some corridors are spared. The pigeon must choose the right one. From the beginning all obstacles were already visible. The second half of the race is a complete catastrophe. The sun shines heavily and there is overheating. Even at 1000 meters altitude. On the ground we see temperatures above 34 ° in Burgundy, 36 ° in the Aube. New stormy fronts are approaching Belgium, new corridors to choose from. The classicrace of this year has undoubtedly been difficult and bad. Many will return in the days that follow and part of the contingent is missing ... Let's not hide this truth.

Falcon and  doping

In his fight, often lost, against the peregrine falcon or another winged predator, the pigeon can boast a highly developed paratympic organ. It uses it to detect weather changes and to adjust its flight to and from altitude. But bad news: the peregrine falcon also has a paratympic organ. And he is even hypertrophic! The peregrine falcon uses it for barometric changes (ascending flight thanks to the wind) but it is mainly for his skill in flight and the violence of the speed changes between the glide flight and the dive and sudden changes in direction when he follows his prey from behind, that he will benefit from this organ.  

Finally, Creagh Breuner, one of the researchers, collected blood samples from birds with this paratympic organ. Samples taken in periods without significant weather changes, others made 12 hours before a storm (snow for some, stormy for others). He himself had hypothesized that sudden drops or increases in atmospheric pressure could be a signal that caused an increase in glucocorticoid hormones. These are associated with stress and promote survival instincts. But no single sample revealed any variation in the level of corticosterone ... Unlike some people whose metabolism naturally produces too much testosterone or cortisone, this is not the case with birds. Let this be said!

Hupez.G.

 


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