In order to understand everything, ornithologists were invited to the construction site. On how the main birds work, read the first part. And now we will analyze the answer to question number 2.
Will the birds come across a skyscraper?
How the birds see
Bird sight is different from human. Their eyes are more perfect. Acute vision is a question of survival of birds, so evolution has taken care of this.
The eyes of birds are more human in relation to body size, their lens changes shape more quickly and more strongly. In many species in the organs of vision there are special devices that facilitate survival in flight conditions.
For example, "binocular vision" allows them to evaluate the distance well. Those who fly in the absence of light, have increased twilight vision – in the retina there are more "rods", although fewer "cones".
The eye of a long-eared owl. More sticks – fewer cones. Photo Suren Manvelian from here
In seabirds, like seagulls, improved vision in the conditions of fog. In general, it is believed that birds see a better person in 4-5 times!
So do birds see a skyscraper? If you see it, then be sure that they see it even better.
A tower from the height, as it is customary to say "bird's flight". In fact, this is not true – the main stream of birds goes on elevations of up to 100 m. In any case – the tower is visible to them well
Nevertheless, it's too early to put a blessed point.
The problem of glass
The problem of glass does exist. Moreover – it is in third place among the anthropogenic factors in the number of cases of bird deaths. On the first – motor transport. On the second – death from the paws of domestic animals – cats and dogs. Even if your furry friend has hunted only for Whiskas all his life.
It is necessary for him to get used to a little in the yard, he will be a mortal danger for the birds. Watch out for the pets.
But back to the glass. What's wrong with him? It's like air. The worst case – the enfilade from the windows – seems to the birds that this is a walking way.
In such cases, the bird can see the possibility of a through passage. Photo
The second of the most dangerous options – solid glass walls of houses – birds can lose their orientation by flying into such glass jungles.
Glass jungle. Vancouver. Photo from here
A point skyscraper with well-defined contours is not dangerous from this point of view – birds understand that there is something wrong and it's better to fly over the structure.
Photo by Oleg Popov
Observation data confirm this – despite the fact that the façade is more than half ready, the collision of birds with
"… The construction of the building to an altitude of about 300 meters now does not change the situation with flying birds. Sloping glazing also has no effect on birds … "From the technical report on operative ornithological monitoring of Lakhta Center for April-June 2017.
And what about the stories about birds hitting skyscrapers? For example, in May the Internet flew around the news about a case involving the death of 400 winged in Galveston, Texas.
A light trap
Concerning such cases – and this is precisely the emergency situation, not the usual practice, ornithologists have different versions. Priority is a light trap.
A light trap operates under conditions not just bad, but nightmarish visibility. In Galveston on May 16, storm raged – it was raining, a strong wind blew, then the night fell on the city … A good dispatcher in this weather will not drive the strip to the strip. But birds can not cancel flights, alas, no one. A brightly lit point skyscraper – apparently the only thing that was clearly visible in those conditions and the birds moved towards him as a refuge. The result is sad.
Three birds surviving in Galveston. Photo
Stories about the light trap – not one thousand years.
The problem of lighthouses has existed for a long time – not only seafarers were hurrying to them, but birds too, only the latter were often broken. By the same scheme, only with a happy ending are meetings of birds and ferries in the sea. Feathered during the flight through the large water spaces quite often cover with a brightly lit steam, however, this time the light trap really turns out to be a refuge.
What should I do about this problem?
Ornithologists advise the owners of the skyscrapers to muffle the light, and better – and at all do without lighting during the migration period and especially – in bad weather. In Canada, scientists suggest dimly highlight the building in green. It sounds kind of strange – how the most natural – green – can scare away birds? But feathers well distinguish natural green and artificial green illumination. Apparently, just because the real green they saw a lot and understand the right and wrong shades. Anyway, these are the conclusions of the scientists.
That very skyscraper One Moody Plaza from Galveston – after the incident the illumination was turned off for the time of bird migration. Photo of the Popmechanics from here
In addition to the light trap, a number of cases can be explained by other versions. For example, a magnetic anomaly.
Why do birds return home? Gastuknik, who remained nesting in the Lakhta area, flew thousands of kilometers not somewhere abstractly "to St. Petersburg." He flew to a particular place, exactly where he had a nest.
Every bird flies to his home. Screen. Source
The first thing that birds do when they become independent – are resettled from their parents. It is an instinct that protects from intra-family ties (and genetic weakening of offspring) and the instinct dictating expansion to a new territory is the same one that drove people from Africa to settle into all suitable islands and continents. Young birds are building a nest in a new place, since then they have returned to the same place. It's a house, literally.
Next year these storks will arrive here
And now the question. How do birds know where to fly to return? Maybe they somehow remembered the road? Scientists conducted experiments – specially rejected the birds from the course. The youth returned unmistakably to the direction, and experienced birds flew as if on a navigator – to a specific place.
There is no exact explanation for this fact so far. Someone thinks that birds remember the way – they fly along the stars or along the guides, which serve as river beds, mountain ridges, etc.
Perhaps the birds also know how to distinguish between the constellations and orient themselves on them
But there is a version that evolution has given birds a more reliable way – they can somehow navigate the magnetic field of the earth. It's almost like a built-in compass.
This version also explains a certain number of unexplained cases of bird deaths when they massively break up about a building or cater for cars – the cause may be magnetic anomalies (so-called magnetic storms).
But back to Lakhtu. While problems with bird migrants are not observed. Birds fly about their business, skirting the site. The builders erect the building. Ornithologists continue to observe. Designers develop a special highlight for the period of migration – not bright, only to denote the contours of the tower, not attracting birds. And the Lakhta Center has a new symbol – a bird.
The author of the sketch is Daria Kuznetsova
Thank you for your help in presenting the materials of the specialists of the Faculty of Biology of St. Petersburg State University