Life Of Birds

To celebrate the centenary of the Migratory Bird Treaty Act, the first law for the protection of migratory birds promulgated in 1918 in the United States, the "National Geographic" has decided to dedicate the entire year 2018 to birds. In the January, February and March issues, "National Geographic Italia" has already told in many articles and insights the wonderful world of birds, capable of so many wonders that the existence of birdwatching seems right and inevitable, so much so that one wonders why has not yet become a school discipline (a discipline which, moreover, would give meaning to many trips).

It would be nice to discover, even at school, that the howling albatross, with its 3.5 meters of wingspan, spends 95% of its time in flight, covering the equivalent of eight round trips on the Moon. The young swifts, once they leave the nest, spend three to four years in flight without ever touching the ground: in the air they eat, drink, sleep. The birds of our cities and our countryside build their nests only until around noon, that is, until the twigs are still damp with dew, therefore malleable. Magpies, in addition to being able to recognize themselves in the mirror as very few other mammals (and apparently no other birds), perform real funerals for their companions, noisily gathering other magpies around the deceased and then completely silent for a few minutes. The irresistible long-tailed tit, on the other hand, build a sack-like nest lined with feathers and composed of lichens and cobwebs, capable of deforming as the many chicks of the brood grow.

And why, some will ask, should we know all these things? What is it for? We will try to respond with this reading path.

In the huge amount of books dedicated to this fascinating world, we have chosen some that can change our gaze, with binoculars or simply with the naked eye, perhaps from the window of the house while the birds eat the sunflower seeds that we left them for overcome the winter frost (remembering, if possible, to accompany them with a container full of water, and checking that it does not freeze).

Feathers and feathers

In his Winter Ravens, which we have already reviewed, Bernd Heinrich during a devastating snowstorm in the woods of Maine (which we imagine different from our recent Buran / Burian) asks himself:

How can the little bullfinches out there survive that I heard flying in the darkness yesterday morning? What happens to the even smaller rulers, to the creepers and to the gray tits? Where do crows take refuge on a night like this? How do they manage to hold on to branches? 

In a sort of remote scientific dialogue, Thor Hanson, a former pupil of Heinrich, answers in his illuminating Piume - The evolution of a miracle of nature (Il Saggiatore, 2016, 449 pp., Euro 22. Tit. Or. Feathers, translation by Allegra Panini), where he faces - from every point of view - the feathers and feathers of birds.

The feathers are a "horny formation of the skin characteristic of birds, consisting of a central axis, whose basal part (calamus) is inserted on the skin, while the remaining part (rachis) bears the banner, formed by many fringed lateral appendages", this is how the Dictionary Zingarelli 2018 defines them, where the "frayed lateral appendages" are barbules hooked together. They can be flight feathers and helmsmen (they are responsible for the flight), or they can be side feathers: they are the largest number and have a mainly insulating function, essential for waterproofing the body of the birds while keeping the humidity of the underlying feathers constant. The feathers have a thermal function and include semi-feathers, down, whiskers / bristles and filopfeathers and, generalizing, are feathers without rachis and banner.

If a human being can survive for no more than an hour in the cold water of the sea, a bird, with its much smaller size than ours, should survive a few minutes. So why, paradoxically, "water birds never get wet"? [Hanson, p. 201]. And how come, to answer Bernd Heinrich's question, birds weighing a few grams can survive temperatures as low as -50 ° C?

Their secret, it will be understood, is precisely in the plumage:

On average, the plumage of a passerine includes from 2000 to 4000 feathers (while the lesser swan can have up to 25,000) the vast majority of which are represented by the basal beards or the feathery appendages of the feathers, which are called hyporachids, or simply from duvet. The feathers suitable for flying, on the other hand, only number a few dozen. When tucked neatly underneath the weatherproof outline feathers, the feathers trap pockets of warm, dry air close to the skin and thus allow the birds to survive in colder climates.

The author accompanies us on a journey of discovery of the most microscopic secrets of feathers and feathers, showing us the absolute perfection of these wonderful products of evolution that have their roots in ancient fossils more than 100 million years and that today have many functions : aerodynamics for flying, insulating to protect oneself from water and cold, therefore reproductive aesthetics in males, with shapes at the limits of the imaginable (just think of the peacock's tail, composed of modified contour feathers).

We will learn about the ability that birds have to control every single feather during flight, how and better than airplanes with their flaps, ailerons and stabilizers (the swooping peregrine falcon reaches 390 km / h!), We will know part of the impressive variety of the 42 existing species of birds of paradise (Paradiseidae family) whose males, thanks to the extremely demanding selection made by the females, show off incredible plumage, as we can admire in this short video by BBC Earth.

But Hanson doesn't just reveal the secrets of feathers. Getting involved in the first person, with sympathy and great competence, he broadens the discussion to what feathers and feathers mean, and have meant over time and in many ways, for human beings. Starting from fishing, where we learn that building "flies" with feathers is an art that can give addiction to everything that still concerns the padding of goose feathers in winter jackets, pillows and duvets. Not to forget the fletching of Genghis Khan's nine million arrows ...

Whether it's feathers or feathers, these wonders are largely composed of keratin, the same protein that makes up our hair and nails (you'll agree, with very different results). Indeed, this property is also exploited for industrial purposes:

About five million tons of turkey and chicken feathers are harvested every year in the United States and conveyed to companies such as ConAgra and Purina with excellent profit. From boiled, dried and chopped penne you get a kind of high protein flour that is found in practically every can of dog food and even in cattle food. This flour, although it may seem a bit macabre, is also used to produce chicken food.

Well before this, however, as we know, pens were used for something else and for more than a thousand years they were the fundamental tool for writing, with all that this entailed for the purposes of human cultural evolution. Even today we use pens to write, even if they are plastic and are called “ballpoint pens”. But once upon a time they wrote with goose quills and dipped their quill, naturally hollow and perfect for collecting ink, in the inkwell. The engraving of the tip and the treatments to make the writing quills durable are very well described by Thor Hanson, along with his amused attempts to create working pens himself.

... Then, considering the city of St. Petersburg alone, we know that exports reached a figure of twenty-seven million pens a year. If we take into account the fact that only five usable feathers per wing can be obtained from each bird (corresponding to the largest primary flight feathers), it is not surprising that people have developed a certain familiarity with the taste of goose meat.

But of all the endless uses of feathers and feathers that Hanson recounts, one of the most surprising is this: apparently swallows love to play Quidditch!

In various species of swallows, what apparently began as a competition for the material with which to line the nest has turned into an elaborate ritual that many ornithologists interpret as a real game. When a suitable feather is found, couples or groups of swallows chase each other madly, performing incredible lunges and swoops while grabbing the feather several times in mid-air. Even an individual alone can indulge in this feather hunt, flying with such exuberance that it has prompted even the most rigorous scientists to think it is fun.