In the world of birds.
The similarity of ecological preferences of these groups of species led to the similarity of morphology: small size (up to 10 cm in modern species), short and rounded wings, long strong legs, thin pointed beaks for catching small invertebrates, protective coloration of plumage (see mimicry). Birds from New Zealand are distinguished from true wrens by short tails, reverse sexual dimorphism in size (females are larger than males), a clear tendency to lose the ability to fly in conditions of a shortage of terrestrial predators, an unusually fluffy integumentary plumage, as well as a number of structural features of internal organs. Many of these traits are rare, if not unique, among passerines. This is a prime example of how habitat change affects island species that have lived in complete isolation from mainland fauna for millions of years.
The reasons for the unusual characteristics of New Zealand wrens became clear after studying their DNA. It turned out that of all the passeriformes, which now make up more than half of the entire world avifauna, it is the New Zealand wrens that are the branch of the evolutionary tree that separated the earliest - according to the most recent data, presumably at the beginning of the Eocene. For this reason, modern taxonomists often distinguish these birds in their own suborder. Acanthisitti. Such a separate taxonomic position makes the New Zealand wrens a valuable object for a variety of molecular and morphological studies that can explain many aspects of the life and evolution of birds.
Of the seven species of the family that met the first people of New Zealand about 700 years ago, only two have survived to this day. The most numerous of them is the shooter ( Acanthisitta chloris), which received such an unusual name due to the similarity of its patronizing colors with the uniform of the New Zealand infantry riflemen. Males and females of the arrow are well distinguished by color: the back and top of the head in males are monochromatic green, in females - olive in dark and light streaks. In addition, females are distinguished by a slightly more upturned bill tip and a slightly longer rear toe claw. The current range of the species is both the large islands of New Zealand, North and South, and a number of smaller adjacent islets. The clutch consists of 3–5 eggs; Both parents take part in building the nest and taking care of the offspring. Arrows are found mainly in wooded areas; due to their limited ability to fly, they cannot cross vast open areas, as a result of which they are especially vulnerable to massive tree felling, which fragments the species' range.
The second modern species of the family is the rocky New Zealand wren ( Xenicus gilviventris; see photo above). It inhabits the alpine and subalpine belt of mountains in the western part of the South Island; in the North, populations of the species - probably representing a separate subspecies - have died out in historical time. The usual habitat of this bird is more open locations with bare rock outcrops, often covered with low shrubs. Sexual dimorphism in coloration is less pronounced: males are predominantly green on top, females are brownish. Comparatively large, closed nests with an entrance from the side of the bird are built from dry grass and twigs with inclusions of feathers from other birds. There are usually three eggs in a clutch. Like the shooter, both parents take care of the offspring. The total population of the rock wren does not exceed 15 thousand individuals and tends to decrease; The species is listed in the IUCN Red List as Vulnerable. The main threat to rocky New Zealand wrens comes from persecution by invasive mice, rats and stoats.
The closest relative of the rock wren was the New Zealand shrub wren ( X. longipes), which was distinguished by a darker color of the top, a predominantly gray abdomen and slightly longer legs. The range of this species until the last century was not inferior to the range of the shooter, dividing into three geographical races: X.l. stokesii lived in the North Island, nominative X.l. longipes- on the South X.l. variabilis- on Stewart Island and a number of adjacent small islands. The successive invasion of New Zealand by several species of rats, as well as mice and stoats, led to the extinction of all three subspecies during the 20th century. The northern subspecies was last seen near Lake Waikaremoana in 1955, the southern one in 1968 in the Nelson Lakes National Park. Following a rat invasion on the last stronghold of the Stewart subspecies, Big South Cape Island, the New Zealand Natural Resources Conservancy launched a desperate rescue operation, transporting six individuals to the rodent-free island of Kaimoho. Unfortunately, a small population of birds could not gain a foothold in a new place: after the observation of a pair of shrubby wrens in 1972, birds of this species were no longer seen.
Three more relatively large (up to 30–50 g) species of the family could only survive until the time when the islands of New Zealand were colonized by the Maori natives. This is a long-billed New Zealand wren ( Dendroscansor decurvirostris), as well as two species of large-footed wrens, which until recently stood out as an independent genus Pachylpichas- northern ( Xenicus jagmi) and southern ( X. yaldwyni). The subfossil remains of these birds testify to their more pronounced adaptation to the terrestrial way of life and to a complete or almost complete refusal to fly. The latter, probably, was the reason for the extinction of these species: around 1280 AD, New Zealand was colonized by the Maori natives and their unwanted companions, the Polynesian small rats ( Rattus exulans). It is unlikely that tiny wrens aroused great gastronomic interest among people who preferred larger game, such as flightless ostrich-like moas ( Dinornithiformes), exterminated over the next few centuries. But for rats, small birds and their nests have become desirable and easy prey, because over millions of years of evolution in isolation, they have not developed any means of protection against terrestrial mammals. The first European colonists did not find either long-billed or large-legged wrens in New Zealand.
The last, seventh species of the family is the famous Stephen shrub wren ( Traversia lyalli), who lived on the tiny island of Stevens (or Stephens) in the Cook Strait between the North and South Islands. The legend about the disappearance of this bird is widely known (see The cat that destroyed an entire species of birds). However, in reality, this story is somewhat more complicated, but, alas, no less tragic. Archaeological finds eloquently testify that up to the time of the settlement of the Maori, the species was common on both large islands of the archipelago. The invasion of Polynesian rats led to the extinction of this bird everywhere, except for a single island, which the malicious rodents could not penetrate. But with the appearance on Stevens of the first colonists of European origin, the island was inhabited by other predatory companions of man - cats. The cat of the first keeper of the newly built lighthouse, David Lyell, in the summer of 1894, began to bring the owner "trophies", in which he quickly recognized something interesting for science, after which he handed over the carcasses to local naturalist Walter Buller.
Unfortunately for a rare bird, Tibbles - that was the name of the cat - did not act alone. Old documents from the early settlers of Stevens show that in February of the same 1894, at least one pregnant cat was released onto the island, which clearly managed to survive and successfully raise offspring. A few years later, the island was literally teeming with alien predators: Robert Cathcart, the new lighthouse keeper, reported on his own destruction of over a hundred feral cats in 1899 alone! However, a smaller concentration of fluffy killers was enough for a small, practically incapable of flying bird: the last information about a meeting with this wren dates back to August 1895. Subsequently, Stevens, by the way, lost both cats, purposefully destroyed by local services for the protection of natural resources by 1925, and the last primary forests reduced to the needs of local residents.
In the bottom line, we have the following picture. The family of birds, endemic to the island archipelago, has been reduced to two species during two waves of settlement by humans and synanthropic species of mammals, and one of them is in a vulnerable position. In some cases, their habitat has been destroyed, in others it has undergone significant anthropogenic transformations and, without the investment of serious forces and material resources, cannot be restored to its original form again. The environmental legislation of modern New Zealand is one of the most stringent in the world, but a significant proportion of the resources of the country's profile organizations is spent on correcting the mistakes of previous generations. One of the most destructive of them is the introduction of numerous species that were not previously characteristic of the archipelago. The same problem is a key one for many other tropical and subtropical islands, which to this day harbor the remains of pristine flora and fauna that are fighting for survival against hordes of alien invaders.
In the photo - a rocky New Zealand wren ( Xenicus gilviventris). Photo: © Robin Bush from nzgeo.com
Pavel Smirnov
The situation around the Great Barrier Reef continues to deteriorate and threatens to turn into the biggest disaster in human history. reCensor remembered when the ecology was still in a state of emergency due to human actions.
Scientists believe that, despite all the efforts of environmentalists, in the near future the world's largest coral reef is threatened with destruction. More recently, experts have noted that more than 50% of the Great Barrier Reef in Australia is at the stage of death. According to updated data, the figure increased to 93%.
The formation of such a unique natural formation occurred about 10 thousand years ago. It includes almost 3 thousand different coral reefs. The length of the Great Barrier Reef is 2.5 thousand kilometers with an area of 344 thousand square kilometers. The coral reef is home to billions of diverse living organisms.
In 1981, UNESCO recognized the Great Barrier Reef as a protected natural wonder. However, in 2014, environmentalists began to notice that many corals had lost their color. It should be noted that similar changes have occurred in many coral reefs around the world, so scientists initially thought that this was a standard anomaly. But after a few months, it became clear that the number of bleached corals was growing exponentially.
Terry Hughes, head of the James Cook University Center for Excellence in Coral Reef Research, said coral bleaching almost always leads to coral death. “Corals can be saved if the bleaching rate does not reach 50% percent. More than half of the Great Barrier Reef's corals currently have bleaching rates between 60% and 100%.
Environmentalists have been sounding the alarm for several years now, as the death of corals will lead to the disappearance of the entire ecosystem. Coral bleaching occurred in several stages. In 2015, there was the largest wave of bleaching, but scientists believe that the largest extinction is yet to come. “The reason for this is climate change associated with global warming. The temperature of the waters in the oceans has risen greatly, as a result of which the corals began to die. The saddest thing is that we do not know how to counter this problem, so the extinction of the Great Barrier Reef will continue further, ”the scientists state. 
Also, one of the reasons for the extinction of corals is the catastrophe of a large industrial tanker that occurred in 2010. As a result of the collapse of the tanker, more than 65 tons of coal and 975 tons of oil fell into the waters of the Great Barrier Reef.
Experts are confident that this incident has become an irreparable environmental disaster. “In the modern world, a trend has formed that leads to the fact that due to extremely careless human activities, almost all animals inhabiting our planet will die. Even the death of the Aral Sea cannot be compared with the destruction of the Great Barrier Reef,” notes Professor Terry Hughes.
Most of the largest environmental tragedies occurred in the XX-XXI centuries. Below is a list of the 10 largest environmental disasters in history, information about which was collected by reCensor correspondents.
One of the largest incidents that caused serious damage to the environment is the crash of the Prestige oil tanker. The incident happened on November 19, 2002 on the coast of Europe. The ship got into a strong storm, because of which a huge hole was formed in its hull, more than 30 meters long. Every day, the tanker carries at least 1,000 tons of oil, which is thrown into the waters of the Atlantic. In the end, the tanker broke into two parts, sinking with all the cargo stored on it. The total amount of oil that entered the Atlantic Ocean was 20 million gallons.
2 Bhopal Leak methyl isocyanate
In 1984, the largest toxic fumes leak in history occurred. methyl isocyanate in the city of Bhopal. The tragedy caused the death of more than 3 thousand people. In addition, another 15,000 people later died as a result of exposure to the poison. According to experts, the volume of lethal vapors that ended up in the atmosphere amounted to about 42 tons. It is still unknown what caused the accident.
3. Explosion at the Nipro plant
In 1974, at the Nipro plant, located in the UK, there was a powerful explosion, followed by a fire. According to experts, the explosion was so powerful that it could only be repeated by collecting 45 tons of TNT. 130 people became victims of the incident. However, the biggest problem was the release of ammonium, resulting in thousands of people admitted to hospitals with vision and respiratory diseases.
4. The largest pollution of the North Sea
In 1988, the largest accident in the history of oil production occurred on the Piper Alpha oil platform. Damage from the accident amounted to US$4 billion. The accident caused a powerful explosion that completely destroyed the oil platform. Almost all the personnel of the enterprise died during the accident. Over the following days, oil continued to flow into the North Sea, which is now one of the most polluted waters in the world.
5. The largest nuclear disaster
The largest environmental disaster in the history of mankind is the explosion at the Chernobyl nuclear power plant, which occurred in 1986 on the territory of Ukraine. The cause of the explosion was an accident in the fourth power unit of the nuclear power plant. The explosion caused the death of more than 30 people.
However, the most terrible consequence is the release of huge amounts of radiation into the atmosphere. At the moment, the number of people who died as a result of radiation contamination in subsequent years has exceeded several thousand. Their number continues to grow, despite the galvanized sarcophagus that sealed the exploded reactor.
In 1989, a major environmental disaster occurred on the coast of Alaska. The oil tanker "Exxon Valdez" hit the reef and received a serious hole. As a result, the entire contents of 9 million gallons of oil ended up in the water. Almost 2.5 thousand kilometers of the coast of Alaska were covered with oil. This accident caused the death of tens of thousands of living organisms living both in water and on land.
In 1986, as a result of the tragedy at the Swiss chemical plant, the Rhine River was forever no longer safe for swimming. The chemical plant burned for several days. During this time, more than 30 tons of toxic substances spilled into the water, destroying millions of living organisms, and polluting all drinking sources.
In 1952, a terrible disaster occurred in London, the causes of which are still not known. On December 5, the capital of Great Britain plunged into caustic smog. At first, the townspeople took it for ordinary fog, but after a few days it did not dissipate. People began to arrive at hospitals with symptoms of lung diseases. In just 4 days, about 4 thousand people died, most of them children and the elderly.
9. Oil spill in the Gulf of Mexico
In 1979, another oil disaster occurred in the Gulf of Mexico. The accident happened at the Istok-1 drilling rig. As a result of malfunctions, almost 500 thousand tons of oil spilled into the water. The well was closed only a year later.
10. The crash of the oil tanker "Amoco Cadiz"
In 1978, the oil tanker Amoco Cadiz sank in the Atlantic Ocean. The cause of the crash was the underwater rocks, which the captain of the ship did not notice. As a result of the disaster, the coast of France was flooded with 650 million liters of oil. Due to the crash of an oil tanker, tens of thousands of fish and birds that lived in the coastal region died.
TOP 10 largest environmental disasters in history updated: July 7, 2016 by: EDITION
Recently, a round table "Birds and people: invisible threats and real dangers" was held in Moscow, in which domestic and foreign ornithologists took part. Scientists discussed the problem of the rapid decline in the species diversity of birds around the world. And their forecasts are not comforting - the extinction of birds can lead to the death of mankind.
The extinction of various bird species has recently acquired a global character and has significantly accelerated the pace. In many ways, the fault for this lies with man and his intervention in the life of nature. But there may be other factors as well. In any case, the mystery of the death of red-winged troupials (which many mistakenly took for blackbirds) last December, scientists have not disclosed. But we are ready to predict what a sharp reduction in species diversity can turn into - an avalanche-like jump in evolution. And there's not much to be happy about. New species will adapt already to modern man. But whether he will adapt to them, scientists strongly doubt.
Over the past 500 years, 154 species of birds have disappeared on the planet - one in 65. It seems to be not so much, if you do not take into account that in recent years the rate of extinction has only accelerated. Today, 1,200 species of birds are on the verge of extinction - already one in eight of the currently existing ones. And as it was stated at the round table “Birds and people: invisible threats and real dangers”, the closer to large metropolitan areas, the worse the situation. If in the Moscow region every third species of birds is listed in the Red Book, then in Moscow itself - every second.
This situation is typical for the whole world. For example, in the Delhi region of India until the beginning of the 90s, about three thousand pairs of birds of prey lived - kites, vultures, vultures. But suddenly their population began to decline sharply: in seven years it fell 20 times, amounting to only five percent of the previous number. Local ornithologists were literally amazed by the catastrophe that broke out. Moreover, India is characterized by a careful attitude to all living things, and even more so to birds. Turns out it was the cows. More precisely, not they themselves, but the medicine diclofenac, which in the early 90s in India began to treat livestock. It is difficult to say how effective the treatment was. But when the animals did die, they became the prey of birds of prey and, unwittingly, the cause of their mass death.
Today, the use of such a drug is prohibited in India, but who knows what enterprising humanity will invent next time, especially since pharmaceuticals are developing at a rapid pace. But even without toxic chemistry, a person in one way or another "poisons" the life of birds. According to American scientists, annually up to 170 million (!) birds die due to collisions with electrical wires. True, some good news has recently appeared: Russian ornithologists from Ulyanovsk have invented a fairly inexpensive device that allows them to protect birds from high-voltage damage. So, perhaps soon this figure will become less.
Recently, in addition to wires, radar towers for mobile communications have also appeared. So far, scientists are not ready to say what exactly their appearance threatens the environment. But it has already been noticed that after the installation of such a tower, the birds stop nesting in this area, apparently moving to another place.
In general, the problem is precisely in the decrease in species diversity, since the number of birds itself is not decreasing, but some, on the contrary, is increasing. For example, pigeons. Residents of many cities have long been accustomed to this bird as part of the landscape. And some consider it almost their civic duty to regularly feed the birds. What should not be done in any case, Professor of Zoology at the University of Delhi, Dr. Kumar, is sure: “By feeding pigeons, a person first of all feeds his ego. He does not know what is necessary for this environment, he does not understand that he is interfering with the biosystem and thereby planting a time bomb.
Russian ornithologist Vladimir Galushin also strongly discourages picking up chicks that have fallen out of their nests. “Most birds in the Moscow region have psittacosis and these viral diseases can be transmitted to humans, especially children,” he warns. Moreover, in captivity, the chick will still die. So ill-conceived human intervention in bird life, even with the best of intentions, can be harmful to both one and the other side.
But the greatest fear of Russian scientists is precisely the decrease in the diversity of species. According to Viktor Zubakin, head of the Russian Bird Conservation Union, this trend may serve as one of the signals for the beginning of an avalanche-like evolution of species. “The fact is that the more species of birds or animals, the more stable the ecosystem. And with a stable ecosystem, evolutionary processes slow down. As soon as the balance is seriously disturbed, uncontrolled processes of the emergence of new species begin to occur,” the scientist says.
For the first time, domestic paleontologists Zherikhin, Rautian, Ponomarenko and Eskov, who studied abrupt changes in flora and fauna in the Mesozoic and more distant eras, came to the idea of an avalanche-like evolution for the first time. Its meaning is this - when the leading groups of animals in the ecosystem die out (for a variety of reasons), a rapid evolution immediately begins among representatives of those species that lived on the periphery of the community and previously occupied very narrow ecological niches. So, for example, the extinction of dinosaurs immediately opened up the possibility for mammals to enter a large size class and form ecological forms of large herbivorous creatures and large predators. And the extinction of Mesozoic marine reptiles made possible the emergence of large marine mammals such as seals, cetaceans and sirens.
If we talk about birds, then this was the case with them - this group appeared in the Jurassic period, but it was quite highly specialized. The Jurassic birds were mainly piscivorous divers, like modern cormorants and penguins (since this particular niche was not occupied at that time). And the way to insectivorous forms was closed to them for a long time - small pterosaurs (Pterosauria) like rhamphorhynchus (Rhamphorhynchus) did this in the Jurassic. However, as soon as they died out at the end of the Jurassic period, insect eaters among birds immediately appeared, and the most diverse ones (after all, the diversity of insects themselves was already huge at that time). And the final extinction of pterosaurs in the middle of the Cretaceous added new jobs for birds - predators, soaring fishermen (like albatrosses and gulls) and scavengers.
Since such a violent explosion of the diversity of forms among a previously highly specialized group happened very quickly (by geological standards, of course, because it took millions of years), scientists called such evolution an avalanche. The role of the pebble that launched it was played by the extinction of Rhamphorhynchus (according to the assumption of paleontologists, the birds were not directly related to it - they were supplanted by representatives of other groups of pterosaurs). However, whatever one may say, after their sudden disappearance, most of the current species of birds appeared.
This suggests that the situation, in principle, can be repeated. The extinction of some leading groups of birds in our time may well cause an avalanche-like evolution of some other species of flying creatures, for example, bats. There will be species that can fly during the day, because they will no longer have competitors among birds. And although bats do not do this now, mainly not because of competition from birds, but because their leathery thin wing has no protection from sunburn, but the complete absence of competitors can lead to the fact that advantages will be received. mutant individuals with more "sun resistant" wings. And instead of crows and swallows, red-haired vespers will sit on the wires (that is, hang upside down), and compassionate grandmothers will feed plump and lazy fruit bats, imposingly crawling through city squares. 
Only bats can't sing and are unlikely to learn it.
For humanity, such processes do not bode well, Viktor Zubakin is sure: “The current animal world is much older than man, and the latter, in the process of its evolution, adapted precisely to it. And those species that may appear soon will already be adapting to modern people. And what we will get as a result is hard to say, but most likely nothing good. If we illustrate this with a hypothetical example of diurnal bats, then in their person people will get a new numerous peddler of rabies (there is such a sin behind them), which will be difficult to fight. It is also possible that new species resistant to both chemical and radiation exposure will appear. Therefore, it is not surprising that the scientist has great doubts that humanity, in turn, will be able to adapt to new neighbors on the planet.
In the meantime, it is in the power of people to maintain species diversity artificially - for example, in special reserves. By the way, an important point: in the 1990s, several specially protected natural zones arose in Russia every year. And in the 2000s, when the financial situation in the state seemed to have improved significantly, only two such reserves were opened. In reality, according to scientists, several dozen more are needed. In any case, the fate of birds concerns a person directly. According to scientists, humanity will not survive if birds begin to die out en masse. True, people as a species in this case will disappear earlier.
