3 ecological groups of birds. Ecological groups of birds by type of nutrition. VIII. Homework
Ecological groups of birds are distinguished on the following grounds:
- according to the nature of nutrition,
- by habitat,
- according to the nature of nesting.
Birds from different, sometimes distant from each other, systematic groups often fall into the same ecological group, since taxonomy is built on the basis of genetic proximity, degree of relationship, and common origin.
By habitat There are four groups of birds:
- Forest birds differ from other groups in that they have rather small legs, as well as medium-sized heads. Their neck is not visible, their eyes are on the sides.
- Birds of the coasts of reservoirs and swamps have a very long neck and long legs. They need them to get food in the swamps.
- Birds of open spaces are adapted to migration and therefore have very strong wings. Their bones weigh less than those of other types of birds.
- Waterfowl that live near or in water bodies. These birds are distinguished by a fairly powerful beak, which helps them feed on fish.
Ecological groups of birds by nesting sites:
- Crown-nesting birds build their nests, as the name suggests, in the crown of trees (orioles, zabliki).
- Bush birds place their nests near or in the bushes themselves (wren, robin).
- Ground nesters decide to place their nest directly on the ground (larks, pipits, buntings, waders).
- Hollow-nesting birds live directly in hollows (woodpeckers, tits, pikas, flycatchers).
- A group of birds, burrowers (shore swallows, bee-eaters, kingfishers), live in burrows underground.
Ecological groups of birds by food type:
- Insectivorous birds (tits or pikas) have thin, pointed beaks, thanks to which they can pull their prey off leaves or out of thin crevices.
- Herbivorous birds, including granivores (greenfinches) have a powerful beak thanks to which they can break through the dense shells of fruits. And the sharp ends of the beak help us pull out seeds from the cones of various trees.
- Birds of prey (eagle) feed on various small birds. They have strong legs with powerful claws, thanks to which they grab prey.
- Omnivorous birds (magpies) have a cone-shaped beak that helps them feed on different types of food.
In birds open spaces there are two directions in the development of adaptations. Some birds are adapted to move on the ground in search of food. Fleeing from enemies, they hardly use their wings, but quickly run away. Others, on the contrary, mainly use their wings to move and almost never use their legs. First group of birds lost the ability to fly and they suffered wing reduction. At the same time they have a strong the legs developed, the toes became shorter and the hind toe disappeared. All these signs are useful for running fast. An example of birds adapted to running are various types of ostriches, chickens, etc.
Second group of birds(daytime predators, owls, etc.) have improved wings, and their legs can retain normal development or even be reduced to a certain extent.
Birds of the forest They use all horizons of woody vegetation both for nesting shelter and for food. The legs of most birds, due to their arboreal lifestyle, are designed so that free fingers opposed to each other. This gives them the opportunity to cover branches on both sides. A number of bird species have adapted climb vertically growing trunks trees (nuthatches, pikas and woodpeckers). All these birds the claws of the fingers are very sharp and strongly curved. Woodpeckers and pikas also use their tails to climb., which serves partly as a support and partly for balance during the period of reclining the front of the body. Finches, tits and many other species of birds have adapted to climb branches and hang from below. By climbing trees, birds get their food. The minority finds food for itself using its wings. Thus, forest birds also show adaptation in two directions - in the development of legs and in the development of wings.
Among birds of prey distinguish:
- a squad of diurnal birds of prey that hunt during the day,
- a troop of owls hunting at night.
All these birds have powerful legs, which are armed with large, sharp and strong claws, and crocheted beak.
Daytime birds of prey They settle in steppes, deserts, forests, plains, and mountains. They do not eat plant food at all. Their food is animals, birds, fish and insects. Some types of predators catch live prey (falcons, hawks, eagles, buzzards, etc.), while others eat only dead animals (vultures, vultures, vultures).
Ecological features of swamps and coasts of small reservoirs very similar. Therefore, some bird species are common both to the banks of reservoirs and to swamps.
When obtaining food, some wading birds use predominantly kicks, other - wings.
In the first group of birds, the legs are characterized by a number of features:
- long,
- deprivation of feathers on the ankle joint (ankle),
- considerable length of the front toes, often connected by webs.
All these are adaptations to living in places with viscous soil and the presence of shallow waters. Waders, herons, cranes, storks, ducks, daytime raptors, seagulls, etc. live in swamps and on the shores of reservoirs.
Birds of steppes and deserts. Due to the fact that it is difficult for birds to hide in open spaces, in the conditions of steppes and deserts they have developed long legs and neck. Thanks to this adaptation, birds can inspect the area far away and see the approach of various predators. Birds of steppes and deserts walk a lot in search of food among vegetation, so their legs, as a rule, are well developed. Fleeing from danger, some birds of the steppes and deserts do not fly away, but run away.
To environmental groups by habitat (Fig. 180) unite birds that have the most characteristic adaptations (adaptations) to life in certain conditions, for example in forests, open spaces, reservoirs, their coasts, swamps. In this case, not only the structure, but also the behavior is taken into account.
Often the ecological groups of birds determine by nesting sites : crown nesters, shrub nesters, ground nesters, hollow nesters, burrowers.
Ecological groups of birds are distinguished and by food type : herbivores (including granivores), insectivores, carnivores, omnivores, carrion eaters.
Birds from different, sometimes distant from each other, systematic groups often fall into the same ecological group, since taxonomy is built on the basis of genetic proximity, degree of relationship, and common origin.
Birds of the forest. Most modern birds are associated with forests. Everyone knows our forest birds: tits, woodpeckers, thrushes, hazel grouse, black grouse, wood grouse, well adapted to life in forests. They have short, rounded wings and long tails. This allows the birds to quickly take off and maneuver between trees.
Among forest birds there are herbivores (granivores), insectivores, predators and omnivores (Fig. 181).
Depending on the nature of food, birds have differently developed beaks and limbs. So, insectivores tits, pikas, wrens, warblers They have thin pointed beaks that allow them to get insects from crevices in the bark, grab them from leaves, and remove them from the scales of cones. Sharp claws and long fingers allow these birds to stay on branches.
Granivorous birds – greenfinches, bee-eaters, grosbeaks. They have a powerful beak, which is used to split the dense shells of fruits. So grosbeak successfully breaks the strong fruits of bird cherry and cherry. Sharp ends of crossed beak crossbills allow them to deftly extract seeds from pine and spruce cones.
Large forest birds - hazel grouse, black grouse, wood grouse– spend a lot of time on the ground. With strong legs armed with large claws, they rake the forest floor, selecting seeds of plants, insects, and earthworms. With strong beaks they bite buds, young shoots of trees and shrubs, and feed on juicy blueberries, blueberries, and lingonberries.
They have a typical appearance for forest birds magpie And goshawk(Fig. 182): relatively short rounded wings and a long tail. These birds maneuver beautifully among forest trees and have nimble flight. However, due to the use of different foods, their legs and beaks are developed differently. Hawk – predator: its prey is various small birds. With strong legs armed with powerful claws, the hawk grabs its prey and dismembers it with its curved predatory beak. The magpie has a small cone-shaped beak, which helps it eat a variety of foods (be omnivore ): collect fruits and seeds from the ground, grab insects, worms, a large beetle and even catch a small mouse.
Birds of open spaces They live in meadows, steppes, and deserts. They spend a lot of time on the ground, looking for food among plants. They have strong legs and a long neck, allowing them to detect enemies at great distances. One of the typical representatives of the steppe regions of our country is bustard(see Fig. 179, 6 ). This is a large bird weighing 15-16 kg, feeds mainly on plant foods. Possessing a protective coloring, it often hides among vegetation, becoming completely invisible. The nest is made on the ground, in areas of virgin steppe. Brood type chicks. Due to the plowing of virgin steppes, the number of bustards has sharply decreased, and it is included in the Red Book of Russia.
Typical birds of open spaces are ostriches.
Waterfowl They swim well, many dive. They have a flattened, boat-shaped body, webbed feet, and legs set far back. They move along the ground, clumsily waddling, with a duck's gait. The plumage is thick and has water-repellent properties: the feathers are prevented from getting wet by the secretions of the coccygeal gland, with which the birds thoroughly lubricate the plumage. Representatives of waterfowl – ducks, geese(Fig. 183) , swans.
A typical representative of waterfowl - mallard duck(see Fig. 179, 9 ), feeding in shallow water. Along the edges of its flattened wide beak are horny denticles . When the jaws are not fully closed through the lattice formed by the teeth, the ducks filter the water, leaving food objects in the mouth: crustaceans, insect larvae, small fish, vegetative parts of plants. The mallard feeds at shallow depths. Sometimes, lowering its head into the water, turning over and exposing the back of its body from the water, it collects food from the bottom and strains it. Mallards make nests on the ground among plants. The nest is lined with its own downy feathers plucked from the chest and belly. There are 8-14 eggs in a clutch. Brood type chicks.
Birds of the coasts of reservoirs and swamps They live on the banks of reservoirs and in swamps and have many common structural features. They have long thin legs and neck, a large beak (see Fig. 179, 5, 10 ). In swampy places, their body, raised high above the ground, does not get wet. They feed on frogs, fish, insects, worms, and mollusks. Moving through swamps and coastal shallows, they use their beaks, like tweezers, to grab prey. These are storks, herons, waders. Many of them nest on the banks, not far from the water, others make nests in trees. Storks have long lived next to humans. People take care of them by creating platforms for nests.
Seabirds – guillemots, puffins, gulls– form bird colonies on steep cliffs. They are adapted to hover over the sea surface (Fig. 184).
Ecological groups of birds according to feeding methods. A peculiar group of birds that forage in the air - swallows And swifts(Fig. 185 and 180, 1 ). They spend almost their entire lives in the air, hunting for insects from morning to evening. They have long sickle-shaped wings. The beak is small, and the mouth opening is huge, the corners of the mouth go behind the eyes. With their mouths wide open, they catch flying insects, while the size of the oral funnel is increased by the bristles located at the corners of the mouth. In good dry weather, insects rise high above the ground, and when air humidity rises, the wings of insects get wet and they fly low above the ground. Swallows and swifts follow them, so the flight of swallows and swifts predicts the approach of rain.
Predators have common characteristics (Fig. 186 and 180, 3 ). They have large, strong legs armed with sharp claws and a hook-shaped beak. They have such signs diurnal carnivores birds, owls and even shrikes, related to songbirds. The prey of many predators are small animals, which they look out for from great heights, flying over the fields. Other predators catch small birds, feed on fish and large insects. Birds of prey fly beautifully, among them there are those that soar for a long time, for example buzzards, eagles And vultures. Falcons chase prey in the air, and then, diving on it, can reach speeds of up to 300 km/h. They have sharp, crescent-shaped wings that enable fast flight.
Ecology of Birds The geographical distribution of birds is extremely wide. They populate almost the entire surface of the earth and penetrate north to the Pole. The number of nesting bird species on Rudolf Island (Franz Josef Land - 81°51/N) is 8. During the drift of the icebreaking steamer "Sedov" at 82°N. w. Little auk, puffin, three species of gulls, and guillemot were seen. On Grant's Land between 82 and 83° N. w. Snowy owl, tundra partridge, snow bunting, several species of waders, tern, skua, eider, long-tailed duck and brent goose nest. Employees of Russian drifting polar stations have repeatedly observed birds such as snow buntings and seagulls in the North Pole area.
In the extreme south, as recent observations of Soviet Antarctic expeditions have shown, birds penetrate even into the interior of the Antarctic continent.
The vertical distribution of birds is also quite significant. Cassowaries in New Guinea are found at altitudes of up to 2 thousand m above sea level. Gulls and terns in highland Asia were observed at altitudes of up to 4,700 m above sea level, and vultures - at an altitude of 7 thousand m. Even hummingbirds in some places are common up to an altitude of 4-5 thousand m. On the other hand, some seabirds (eiders, cormorants, penguins) when obtaining food, dive into water to a depth of 20 m.
The wide distribution of birds and their presence in very diverse, often unfavorable living conditions is understandable if we take into account a number of progressive features of these animals. Thus, birds, most of which have a constant and high body temperature, can withstand a variety of environmental temperature conditions relatively easily. It is especially necessary to keep in mind the perfection of reproduction, in which the eggs develop in relatively constant conditions of the nest (primarily temperature).
Possessing the ability to fly, birds can relatively easily overcome obstacles that are impassable for most other vertebrates (including mammals). The ability of birds to move quickly allows them to inhabit areas where existence is possible only in a few months of the year, and to fly from these areas, sometimes over vast distances, to places where living conditions at a given time of year are more favorable. The colonization of arctic and boreal spaces by birds is in the vast majority of cases associated with the indicated biological trait of birds.
From the above, of course, it does not follow that the possibilities of distribution of these species are unlimited. Although birds are able to tolerate very diverse temperature conditions, the importance of the temperature factor in the life of birds is enormous. The northern limit of the distribution of insectivorous birds is ultimately determined by temperature conditions, since at low temperatures there are few insects, that is, food; In addition, the short period of insect activity during the year does not provide the opportunity to feed the chicks. Temperature conditions greatly determine the distribution of plant species with which birds associate as a source of food or shelter. The indirect effect of temperature on the life of water and wading birds is of great importance, since cold temperatures cause freezing of the soil and water bodies where these species feed.
Research by V.V. Stanchinsky and P.V. Serebrovsky has established that the northern limit of the winter distribution of mallard ducks, mergansers, sea and tufted ducks, and goldeneye coincides with the January isotherm of -4° C. The -2° C isotherm determines the limit of the winter distribution of some loons, grebes, whooper swan, pintail duck, woodcock, snipe and some others. Mass wintering of waterfowl, herons, and waders is limited by the January isotherm of +3° C. It should be taken into account here that low temperatures sharply increase the body heat transfer of birds. Thus, a bird the size of a sparrow at 22° C emits 1339 kJ per hour, and at 14° C it is already 4166 kJ. Increased heat transfer naturally causes an increased need for food, and the possibility of obtaining it at this time, on the contrary, is reduced.
The direct importance of humidity for the distribution of birds is relatively negligible. This is understandable, since the structure of the skin reliably protects the bird’s body from drying out and getting wet. Only unusually long cold rains can have a detrimental effect on the body condition of birds. First of all, species that do not have a coccygeal gland suffer, whose plumage therefore easily gets wet. Such are, for example, bustards and little bustards.
The indirect value of humidity is incomparably greater. During droughts, the area of reservoirs and swamps is reduced, animals and plants that serve as food for birds such as ducks, waders, marsh hens, etc. die. Increased humidity, often associated with heavy clouds and low temperatures, disrupts the normal functioning of many species of plants and animals. Plant seed production decreases, many insects become inactive, and their reproduction is reduced. As a result, feeding conditions for birds deteriorate. Increased precipitation often leads to flooding of nests and death of eggs and chicks. It is curious that birds, after the death of their nests, begin nesting again.
Light conditions are essential in the life of birds. This can be seen from the fact that the vast majority of birds lead a strictly diurnal lifestyle. Reducing the duration of the daylight hours makes the existence of many birds difficult, as it reduces the possibility of obtaining the required amount of food. It should be taken into account that the length of the day decreases in the autumn-winter period, when the need for food increases due to lower temperatures. As a result, the gap between the need for food and the ability to obtain it becomes so large that many species are forced to migrate south, to longer day conditions. It is characteristic that often birds, flying somewhat to the south, do not leave the boundaries of their characteristic landscape zone, and although the temperature conditions do not improve, the longer daylight hours provide the opportunity to collect the required amount of food here. Apparently, the winter migrations of tits, tap dancers and a number of other birds are largely connected with this. On the other hand, there is an opinion that the flight of a number of species to the north in spring for nesting is associated with relatively short days in tropical latitudes.
The sensitivity of birds to a lack of light varies significantly among different species. Here are some data characterizing the critical minimum illumination, expressed in lux (i.e., in units of illumination created by one conventional international “candle” from a distance of 1 m with perpendicular incidence of rays over an area of 1 m2): finch - 12, flycatcher - pied - 4, cuckoo - 1, field thrush - 0.1.
Excess lighting has no negative meaning. In the Far North, where the sun does not set for several months in the summer, nocturnal bird species do not suffer deprivation and easily switch to a diurnal lifestyle. Such are the white and hawk owls, the tiger-footed owl. Moreover, it is the continuous daylight that makes it possible for a number of birds to breed in the Arctic during a very short summer. It has been noted that feeding of chicks in some species is carried out around the clock (guillemots), while in others - with a very short break in the middle of the night (passerines). As a result, the period of development of chicks in a nest in the Arctic is shorter than that of the same species, but in more southern latitudes. Apparently, development occurs faster in the young after leaving the nest.
There are relatively few specialized nocturnal birds. These include eagle owls, owls, and kiwi. However, some nocturnal species also hunt during the day when there is a lack of food, for example, the short-eared owl and some owls. There are species that lead a crepuscular lifestyle. Such are nightjars and some herons.
Ecological groups of birds
Due to their wide distribution, birds have adapted to very diverse living conditions. As a result of this, various ecological groups of birds arose, characterized by their attachment to certain habitats, using certain food and developing, to one degree or another, unique adaptations for obtaining it. The system outlined below is based, on the one hand, on the connection of birds with the environment (forests, swamps, ponds, etc.), on the other, on the nature of food and methods of obtaining it. It must be borne in mind that the overall diversity, and most importantly, the depth of adaptations to life in various environments in birds is much less than in all other terrestrial vertebrates. Thus, among birds there are no species that live only in water (like, for example, cetaceans, some tailed amphibians); Birds have not adapted at all to life in the soil (like, for example, moles among mammals). In terms of analysis, the birds remained a very monotonous integral group.
Bush-forest birds
A particularly large group of species whose nature of connections with the forest environment is very diverse.
1. The most specialized group are tree-climbing birds. They forage for food in trees (or bushes), and here they also make nests on tree branches or in hollows. In connection with foraging in trees, the paws are strong, usually with curved claws; Many birds (for example, woodpeckers, nuthatches) have two fingers directed forward and two back. Woodpeckers have a tail, the feathers of which are hard and elastic, and serve as a support when climbing. When climbing, parrots use their beaks to grab onto branches.
By the nature of their diet, bush-forest birds are insectivorous, fruit-spermivorous and nectarivorous.
Examples of insectivorous birds are woodpeckers, which destroy bark and wood with their strong chisel-shaped beaks, extracting insects and their larvae. Pikas, nuthatches, and whirligigs, which have a thin and long beak, get food from crevices and cracks in the bark.
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