Tour to Neocene
In an antiquity people – a unique intelligent species on the
planet Earth – believed their world had been disc-shaped, and “the world’s end”
was meant as something self-evident. When it was found out that the Earth has
a spherical form, the concept of “world’s end” has not disappeared. It simply
became designating a kind of very far place, not similar to the habitual world.
Perhaps, from all places on the Earth Antarctica fits to this concept most of
all – it is the most southern continent of the planet. Even in Neocene epoch
it still remains rather rigorous place. And yet the unique life exists here,
not similar to that at the other continents.
Changes of flora and fauna are connected in addition to other circumstances with the location of the continent at the planet surface. And Antarctica shows this dependence most clearly. In Mesozoic era Antarctica was a part of huge southern Gondwana supercontinent. After its split this continent drifted to the south slowly, and has firmly taken its stand at the South Pole in Cenozoic. It had determined a nature of the continent in many respects. During the waves of global cooling the ice cover began forming, and at the end of Cenozoic it gradually closed the entire continent completely. Terrestrial life in Antarctica has almost disappeared, except for few kinds of tiny mites and insects, and several kinds of grasses and mosses. In some parts of the continent there were some more or less extensive ground patches lacking ice cover – these areas had been named “oases”.
During the Neocene warming the ice cover of the continent began melting actively, and “oases” had started expansion. The coast of Antarctica turned free of ice gradually, and at the exempted grounds life began expanding.
Glaciers have destroyed the primordial terrestrial fauna of the continent, and for a long time this continent had been populated only by natives of the sea – by penguins, gulls and seals. During the climatic cataclysms accompanied the change of Holocene by Neocene all of them have died out: the pattern of sea currents, on which the productivity of the sea depends, had changed too deep. In the subsequent epoch more and more extended oases of Antarctica had begun to be occupied at first by plants and insects, and then by birds. And once there had been a year when some terrestrial birds have not migrated out, but have remained to winter in Antarctica and have survived. But how many failures preceded this event? This is outside the confines of human knowledge…
In Neocene epoch Antarctica is still rather difficult place for a survival. It had shifted only a little relatively to its position in Cenozoic epoch. Only the edge of the continent directed aside of Indian Ocean had considerably shifted to the north. And at the most part of Antarctica polar day is replaced by polar night. But nevertheless the warm and humid climate of Neocene has affected a nature of this rigorous region. Summer in Antarctica is rather warm and sunny, and in winter the thick layer of snow falls, protecting terrestrial inhabitants from frost. Winter in Antarctic region even in Neocene epoch is featured in certain rigour: though the ocean smooths temperature contrasts and the temperature does not fall below 20 degrees below zero (compared to the temperature record of -88°С° fixed in human epoch it looks like tropical heat!). From ocean snow clouds come in regular way, and thickness of snow cover reaches two meters and more. Snow completely closes beds of grasses, transforming the Antarctic landscape to dull monotonous plain. In winter it is practically impossible to survive on the surface of Antarctic snow: strong wind literally blows off to the ocean every live creature that will fail to resist it. Therefore in winter the life concentrates under snow.
Vegetation of Antarctica is made mainly of sedges and graminoids forming endless meadows on plains. Undersized reedmace and cane grow at the wetlands. On the dry hills warmed up by the sun bushes up to one meter high dominate. And cold bogs around of the glacier are overgrown with carpet of peat moss. The vegetation of Antarctica of Neocene epoch has mainly American origin though separate species are closely related to South African forms.
The end of winter is the time of hunger for inhabitants of Antarctica: all insects that have failed to hide well enough are already eaten, and the significant part of seeds is already found. But in windless weather on snow warmed by sun the tiny insects – springtails – gather. These creatures eat everything brought by wind: dead insects carried away by wind from other continents, microscopic cold-resistant microalgae, the rests of plants. Colonies of these insects are similar to the ground pepper strewn on surface of snow. These insects represent the food source for larger inhabitants of the continent which dig tunnels in the thick of snow. Of course, these insects represent very poor meal, but someone is glad to find even this food.
On a surface of snow prominency appears, then breaks to some lumps, and from under it the small creature appears. It creeps out on the surface of snow, shakes the body and begins leaping fussily here and there, looking in sides. It looks similar to small rodent, but distinctions become quite obvious when at one jump this creature slightly opens… wings. It’s a bird, because mammals have not reached the coast of this continent. For fussy movements and small size this bird has got the name mousebird. For a white spot under beak this bird is named white-throated mousebird. It is a representative of the most numerous species of these endemic birds in Antarctica. In winter all mousebirds dig holes under snow, using strong beaks, and almost do not appear at the surface. But at the end of winter when it is not enough food for them, they appear on snow more and more often.
Having got out of snow, mousebird searches for a congestion of springtails. It is not afraid of predators: on snow-covered plains of Antarctica there are no creatures yet able to catch even this tiny bird. And it seems it is lucky: on snow it sees a spot of brownish-red color. It is not blood as it may seem, but a colony of unicellular algae. Having come nearer to the patch of colored snow, the bird notices with its keen eye a congestion of tiny randomly jumping creatures. Springtails are feeding, sucking out cells of microscopic algae. Mousebird, fairly yearned for the last some hours, begins devouring these insects greedily. Until springtails have run up, it managed to dull the edge of hunger.
Difficult season comes to an end gradually. There comes spring, and the sun rises above the horizon higher and higher every day. Snow begins melting and turns more and more dense. Mousebirds are compelled literally to drill it, renewing collapsing tunnels. But there and here there are thawed patches where small insects gather to get warm. Mousebirds also spend less time in their holes. They frequently get out of snow to get warm. Having fluffed up feathers, small birdies for hours stand on snow, greedy absorbing sun warmth. From time to time they move to have a snack of insects, but then return to favorite place. Bit by bit snow thaws completely and then the network of paths treaded out by birds in an autumn and in winter becomes visible. These paths frequently turn to streams via which melt water flows down to the rivers.
Marshes are overflown with melt water, and peat moss soaks it in, becoming similar to sponge. At this time marshland inhabitants try to leave moss to avoid sinking. One inhabitant of the moss escaping from flooding is a large beetle with an oblong body – moss leaf beetle. It had succeeded to emerge from safely wintered pupa before this moment, and is ready now to the first flight in its adult life. It is not afraid of snow lying in some places, and of rather cold weather. The beetle of black color with red legs creeps up on stalk of grass sticking out lonely and turns its back to the sun, having slightly opened its elytra. When its body has got warm enough, the beetle has stretched wings and has flied up. Its streamline body is adapted to resistance to bitter winds blowing from the central glaciers of Antarctica, and the beetle almost does not go off-course when gets in gust of cold wind. These beetles live in parochial zone of mossy marshes surrounding glaciers.
In spring lowlands appear completely flooded, and all their inhabitants gather on the heights overgrown with grass. The rivers of Antarctica are short and fast, therefore the high water comes to an end quickly. When refugees from lowlands return to the places they lived in, the efforts connected to breeding begin: time favorable for it is too short, and it is necessary to hasten. First courtship rituals at white-throated mousbirds begin: these birds have time to rear two hatches of nestlings for a summer season.
For courtship display white-throated mousebird males choose places at some height: they get on stalks of last year’s grasses. Every male keeps at the certain distance from neighbours and sees all their movements. Mousebird males begin courtship games at the dawn. They involve females by wing flapping. Thus bright pink spots on sides of birds become appreciable. Usually males know each other well enough, and the outsider bird joined the colony takes a place somewhere at the edge, at the eminences less convenient for courtship display.
Sometimes at the leks mousebirds of other species appear. The species closest to white-throated mousebird is necktied mousebird. This bird differs from white-throated mousebird in appearance – on its neck and breast not white, but black feathers grow. In the rest the colouring of these birds is similar: both specis have brown background color with short strokes on back. The sounds uttered by representatives of these species in courtship season differ greatly: birds do not understand signals of each other at all. Probably, not understanding because of it the importance of events taking place here, male of necktied mousebird appears casually at the lek of white-throated mousebirds. Usually these two species live in different places, but after a high water some birds still stray in searches of way home. Obviously, this male has simply lost the way. White-throated mousebird males are excited, and they are interested with the only problem – is the bird appeared at their lek a female ready to nesting. But the male of necktied mousebird is not only not-a-female, but it belongs also to completely different species. And the strain arising at the gathering of numerous arrogant males in the prime of life and deceived in expectations in addition, finds a natural exit: males of white-throated mousebird attack the stranger and peck it one by one. Impacts of thick beaks rain down on head and back of necktied mousebird male, while it gets away from the territory of lek. This aggression is quite natural: between close species of animals such relations always take place, if obvious mechanisms of distinction of insiders and outsiders had not been developed.
After a short chase and triumphal exclusion of a stranger white-throated mousebird males return to the former places and display goes on. Their aggression has found an exit, and they almost do not pay attention to the representative of one more species – to striped mousebird. This bird differs from white-throated one in body colouring in great degree: its whole body is patterned with cross strips forming excellent camouflage colouring. Female of this species runs fast beside to lekking ground, but only the nearest to it displaying male has reacted to its presence.
But the appearing of the female of their own species renders the immediate effect to males – they amplify the intensity of displays, begin shaking on stalks and clap their short winglets intensively, as if going to fly up. Female does not pay attention to younger ones perching at the edge of a colony: it favours more to large male which on the spot begins squatting, “bowing” in front of the female with wings lifted up. The pair is formed quickly, and male withdraws female to its territory. And its place at the lek another male occupies on the spot.
While relations between birds are not too firm yet, male does not let female to cross borders of its territory: he bars her way, if the female tries to break borders and to go out. At the male’s territory there is a convenient “apartment” – a last year’s hole. During the winter and especially after snow thawing it had sank strongly and is partly filled with dirt, therefore the pair begins renewing it. Birds dig the ground by beaks and throw it out by legs. When the pair is generated, the male’s aggression increases, and it attacks even birds of other species. Now the focus of its interests is a safety of nest and of the future posterity. When in its territory striped mousebird appears, male attacks it and drives away.
During several next days birds are busy in the nest constructing. They both scurry in thickets, gathering everything useful for soft litter. Grass leaves and feathers represent the best material for this purpose, and between neighbours sometimes fights for such finds inflame. And after that birds have an opportunity to add to the litter the bunch of down ripped out from the neighbour. Birds cover their hole with the found feathers and grass, keeping up any of their relatives of visit of it.
The sun shines for longer and longer every next day, and the ground gets warm. Rhizomes hibernating in the ground wake up and grasses start to grow roughly. Sedge, cotton-grass and various species of graminoids for some days reach the height sufficient to hide a hole of mousebirds and their clutch from an extraneous look. Clutch of mousebirds numbers three eggs, but after successful wintering they can lay four, and in some nests even five eggs. Parental cares take the most part of time of birds – in egg hatching at mousebirds both partners participate. When they replace each other, the freed bird takes a burden of duties on protection of territory. Birds carefully hide a nest location – when female comes to hatch eggs, male puts some leaflets and a bunch of grass on hole entrance, making it less appreciable. Male goes to search for food – he had stayed on eggs for the most part of night, and now he is very hungry. Having moved from the nest to the enough distance, it digs by legs vegetative dust in searches of insects and seeds which have casually escaped after winter.
In spring the sun warms up hill slopes, and it becomes warm, though at night frosts still return. There is a fair weather, and male, having gorged on, has a rest on the knoll open to the sun. Having warmed, it fluffs body feathers and lies on one side, having stretched legs. Eyes of mousebird male are semi-closed: it has a rest. But now it is a wrong time to lose vigilance: after the heat there come dangers. The shadow of wide-winged bird slides on the ground – it is a falcon grackle, the representative of the American family of grackles, returned from wintering. This bird has spent winter at Tierra del Fuego, but in spring falcon grackles fly to Antarctica among the first migrants. Mousebird male had been escaped from the predator by camouflage colouring, and also because it, strangely enough, has delayed. The shadow of bird had swooped over above it, and white-throated mousebird male is frozen, having nestled to the ground. When the terrible bird of size of a large daw has flied out, male jumps and hides in sedge thickets. The bird flies by again, but mousebird male has already disappeared in grass, glancing on the sky anxiously. When it already was going to leave the refuge, in the side rustle of grass was heard, then flapping of strong wings and the desperate squeak which has sharply broken. From grass one more falcon grackle flies up, holding in its beak killed necktied mousebird. Possibly, the bird lifelessly hanging in its beak is that strayed male which has not found the way to its home marshes. Having hovered above the plain, falcon grackle perches on bush. Having pressed dead body of mousebird against the branch, the bird eats it, looking in sides cautiously. This grackle is a male, it has yellow feathers around of eyes, and eyes are also yellow. Mousebirds living nearby will feel like not so cosy – male has chosen these bushes for nesting. It does not hunt near the nest, but all the same mousebirds will nestle to the ground when it will drag the next prey to the nest.
The beak of falcon grackle has bent down tip, and the bird quickly butchers the carcass of mousebird. After a short rest it flies up and in some hours comes back already accompanied by the female. She differs from the male in absence of the crest and in colouring of head which is entirely black at her.
Nestlings of falcon grackle develop for rather long time, and birds have time to bring up only one brood for summer. The couple of grackles immediately begins nest building. Male tears last year's leaves of sedge and uses them to plait some branches of bush as an inclined ring. It will be a basis of their nest. Some more twigs forming the dome are attached to it then. Male winds connected branches with strong sedge leaves, binding more new rods there. He founds a basis of nest, but approximately from the midpoint of the work female takes upon itself the leading role in building. Male only flies to the marsh to gather building material – sedge leaves and stalks of graminoids. Sedge leaf is tensile, and even after winter it is well kept, rotting completely only to summer. Falcon grackle male tears off last year’s leaf of sedge, perches on branch and begins tearing it to strips, using hooked bill tip. Having torn lots of leaf strips, he flies back to the nest. Here male ceremoniously gives the prepared building material to the female, and she intertwines it into the walls. The nest gradually becomes tighted and takes the final shape of sphere with an entrance looking like a short sleeve. Male gradually ceases to drag grass, and more often carries feathers and fuzzes in beak. It is a signal: the nest is ready, and in it eggs will appear soon. Though at falcon grackles there is only one brood per summer, survival rate of their nestlings is very high: they are among main predators of the continent. Mousebirds have two broods per summer: high fertility of tiny birds compensates high death rate from predators and weather conditions. Even if the first clutch is lost in the beginning of incubation, birds make it again and all the same have time to hatch both broods during the summer.
While falcon grackles are busy in the nest construction, at the couple of white-throated mousebirds nestlings have already appeared. They hatch blind, but covered with rich down. This is an adaptation to survival in conditions when spring frosts come to an end rather late, and autumn may begin too early. Mousebird nestlings are very gluttonous and grow fast, therefore parents should tinker a lot to provide posterity with the necessary amount of food.
In searches of insects white-throated mousebird female has gone to the marshland. Usually birds of this species do not inhabi such places: white-throated mousebird lives in drier areas, and in wetland areas necktied mousebirds prevail. But the main area of necktied mousebirds stretches closer to glacier edge, and on plains more or less stable populations of this species occur seldom. White-throated mousebird searches for forage: in wet marshy ground it is possible to find digging larvae of large tipulids and flies. In Antarctica these larvae replace earthworms absent here. Mousebird fills its craw with larvae and then begins digging moss by beak. It is possible to find something edible in moss, and the bird knows it. It buries head deep between stalks of peat moss, and soon takes out a grub of moss leaf beetle. This fat and slow creature wriggles languidly in bird’s beak. Adult beetles of this species are poisonous, but grubs are edible: they live secretively and hope more for density of moss, rather than for their own inedibility. It seems nestlings will be full for some nearest hours, and mousebird hurries up to the nest to feed them.
When mousebird runs away, moss cushion comes to life. Stalks in various parts of it move, and grubs with flat heads get outside – it’s posterity of moss leaf beetle. They have not reached the full size yet, and the most part of them perishes just at such age. When danger passed out, they continue their only occupation – gnaw tops of Sphagnum stalks.
The moss near to them moves, and from it the adult beetle of this species appears, shining is black elytra. For some time it doesn’t move forward, and then opens wings and flies up. From glaciers in the central part of Antarctica bitter winds blow, but this beetle is well adapted to such conditions. It has streamlined flattened body and very strong wings. The most part of the population of these bugs lives in wetlands stretched along the edge of the glacier.
One more week passes. Mousebird nestlings already open eyes. Due to plentiful forage they grow literally not from day to day, but from hour to hour. On their wings, backs and heads feathers begin sprouting, and the down gradually drops out in lumps. Because of it they look little bit shabby, but every next day become more and more active. They already begin creeping in hole on half-bent legs though poise hardly and fall quite often, trying to rise in full growth. But their appetite has remained the same, and parents are compelled to bring forage all the day round in fact. Nights become shorter and shorter: polar day will come soon.
The first day, when the sun does not go under horizon, marks the beginning of polar summer. This time is marked by occurrence of dense clouds of flying insects. Among them there are not only rather harmless flies and tipulids eating absolutely of nothing, though these are the most mass insects of the Antarctic summer. In Antarctica there are no herds of large herbivorous animals like at other continents, therefore bloodsucking forms represent more exception, than the rule here. But in rivers and lakes mosquitoes and midges have found very favorable inhabitancy, and they pay their annoying attention to inhabitants of this continent. Swarms of bloodsuckers hover above thickets, attacking any live creature which moves and smells like something edible. Falcon grackles hide by turns in their closed jack from these torturers while hatch their eggs. The bird free after hatching tries to fly up higher as soon as possible to prevent the attack of midges, and simply soars in sky for hours outside of their reach.
Mosquitoes willingly hide in holes where mousebirds nest. Here they find for themselves shelter and plentiful meal – fledglings of these birds. But not always their attack finishes successfully. When these insects attack mousebird fledglings, these ones shake up or simply peck off the mosquitoes from each other. It is a kind mark for their parents: fledglings become completely independent soon, and it will be possible to have a rest before a new nesting cycle.
When the time of frosts passed and there is a plenty of insects in air, the new wave of migrants moves to Antarctica from South America. In air there are flocks of birds with pointed long wings – Antarctic swallow-lookers have returned home. They are involved with appeared midges and other insects. It seems as if birds hasten to live: not has had time to have a rest after their travelling, males begin to build hanging nests characteristic for this species on tall stalks of grasses. Pairs at this kind are formed to one nesting season and break up when young birds become independent. Preparing for pair forming, male makes a framework of nest: having gathered some stalks of graminoids or sedges together, it suspends to them from below a loop plaited of grass leaves. Male begins courtship flight above this framework: uttering characteristic vocal trills, it makes circles in air, hanging on the spot from time to time and fluttering. Thus it fluffs feathers on crown, and its red “cap” becomes well appreciable from afar. Across the whole plain males arrange such flights, having settled in more or less regular intervals. They settle in larger number near lakes and marshes, where the insects which serve as food for them are more plentiful, and on dry plain neighbours only occasionally see each other. If in Antarctica terrestrial mammals like rats and mongooses would live, all nests of swallow-lookers would be destroyed in some seasons. But in relative safety of this isolated continent birds became much less circumspect in ways of nesting. A unique local predator really dangerous to small birds is falcon grackle. But birds protect themselves collectively against this enemy: attacking on it, they bang feathery predator by wings in head and seize its back by paws. Swallow-looker’s beak is tiny and this bird can not peck the enemy. But mouth cut is wide, and birds can even bite the enemy and pull its feathers out. Therefore falcon grackles not too frequently visit nests of swallow-lookers.
Female involved with male’s courtship flight first of all examines a basis of the future nest. If the place chosen by male and the nest framework are pleasant to female, she joins male. Pairing at swallow-lookers takes place in air, like at swifts. After pairing birds complete the plaiting of nest together. They work hard for many hours, dragging stalks and leaves, and eventually they make out a spherical nest with one entrance. Nest litter is made of down and feathers, which birds pick up in air. Swallow-lookers have no time for long courtship rituals: the season of insect flight is not too long, and for this time it is necessary to manage to bring up the brood. Therefore soon after building in nests eggs already lay. It happens sometimes, that female already hatches eggs while male still completes an entrance or a wall.
Swallow-lookers just have began brooding eggs, and mousebird brood – the first in this season – already leaves the nest. Young birds almost do not differ from parents, only here and there on their breasts and stomachs the rests of down stick out. Though they do not concede in the sizes to adult birds any more, the all the same still depend on parents. Therefore young mousebirds try to keep closer to them.
In grass the whole network of paths is treaded, on which these birds constantly run. Sometimes the brood of white-throated mousebirds meets congeners, or occasionally somewhere in the distance among grass striped mousebird flashes; it hastens to make way for the aggressive distant relatives. Tracks of mousebirds seem treaded randomly, but in fact they stretch along the richest and sprawling beds of sedges and graminoids, and birds can not worry to be noticed by anybody: only for any instants falcon grackles soaring in height see bird’s back flashed in grass. The brood of mousebirds wanders on the territory: young birds follow adults, having lined up. Male follows ahead and female moves sideways and behind a little: it looks at young birds, urging ones lagging behind. Birds search for food: from time to time adult mousebirds begin digging the ground by beak and legs and take from it a tipulid or fly larva. But while young birds follow them, adult ones will not manage to have a square meal: the successful parent is on the spot literally attacked by young ones. Having squatted and flapping scanty winglets, they open mouths wide, and their parents, obeying an instinct, give larvae to them. Within several days they will have to share food with young birds, but gradually these ones start to search for food by themselves. One young bird which hadn’t got food tries to find it by itself. Imitating its father, it is ineptly picking the ground. Its first attempt of searches of food is ineffectual – mosquito larva had flashed in the dug out hole and had disappeared from its field of view.
Other feathery inhabitants of Antarctica also search for food for themselves, but their prey is larger than any insect larvae. Falcon grackles flutter in height. In this feature they are very similar to small kestrel falcon – hence their name. Because these birds are predators, and fodder resources are limited, they strictly observe unseen borders of territories. Usually there are no conflicts between neighbours, and only sometimes a single bird, old or too young, breaks borders of breeding couple. In this case owners of territory in common drive the single one off, accompanying their attack with calls and menacing lunges. After such attack outsider bird frequently loses several feathers from wing or tail. When the infringer is expelled, grackles continue their daily cares: one bird returns to the nest, and another one flies to hunt. To middle of Antarctic summer in nests of these birds squeak of hungry nestlings is heard, and parents are compelled to hunt almost restlessly.
Falcon grackles track down mousebirds scurrying in a grass. It is enough for young or simply careless birdy to jump out on open place, and falcon grackle swoops down on it. The predator tries to kill prey immediately by impact of beak, or presses it down to the ground by paws and kills it.
Some more days passed. Young mousebirds have abandoned their parents and now are given to themselves. They learn searching for food independently, and the bird, which begins it earlier than others, succeeds in this occupation. But the care of an own stomach is some more half-affairs: having remained without parental care, young birds should protect themselves from dangers which at times have an unexpected appearance. Usually the death overtakes mousebirds on behalf of falcon grackle – one of the most important land predators of Antarctica. When in meadows numerous young and inexperienced mousebirds appear, these birds quickly exterminate about third of their number, bringing up their own nestlings.
The only rescues of mousebird are fast legs and camouflage colouring. But, generally speaking, these small birds are silly a little. Therefore they are not capable to distinguish the cunning and get in traps arranged by one more inhabitant of Antarctica. And there is not animal at all, but a plant dangerous to them.
One original inhabitant of Antarctica is bird-catching sundew, a carnivorous plant closely related to some South African sundews. It differs in large size, and insects not too strongly “interest” it as a top dressing. Various small flies and bugs involved with aroma and nectar of flowers of this sundew willingly fly to them for feeding. And with their involuntary help the plant arranges its traps. Nectar of this sundew has slightly intoxicating effect on insects. Insects, having tasted a fair portion of nectar, simply fall right under flowers, creep under them and do not fly out. When there is a large number of them, the trap is ready.
One young mousebird involved with an opportunity to have a snack quickly and without efforts, tries to reach insects. But road to them is blocked by long ribbon-like leaves of this sundew covered with sticky glands on pedicles. Having touched one such gland by tip of wing, the bird “guards” the plant on, though hardly feels what’s happened. But the plant begins the secretion of sticky juice actively. Mousebird is too young and self-confident, and it carelessly steps on leaf of sundew. Of course, one bird’s paw instantly sticks to it. When mousebird tries to free, it serves as a signal to attack for the plant. As if the spring, its leaf begins curling quickly, crushes and grasps tender mousebird, depriving it of the opportunity of movement. Leaf gradually curls harder and harder, and the bird quickly chokes in “embraces” of sticky green “boa”. When the bird’s contractions fade, the leaf secrets digestive juice, and body of mousebird is gradually dissolved. Nutrients are disintegrated and absorbed by the plant. During this process the leaf of bird-catching sundew literally exhausts itself: from it nutrients flow out, it shrivels and decays. In some days on the ground near the plant the rests of caught mousebird – feathers and some vertebrae – lay only. Near to plants of bird-catching sundew it is possible to notice frequently transparent or striped wings of dragonflies – they also are tempted with easy prey and get into the trap.
Dragonflies belong to dominant insect groups of Antarctica. It was simple to them to get to this isolated continent from South America after the ending of an ice age. And here they have found the new native land. Cold rivers and meadows of Antarctica became the center of speciation of these insects. Dragonfly larvae developed many ecological niches, and even have mastered those belonged to fishes earlier. And in the summer, when active flight of mosquitoes and midges begins, dragonflies undergo metamorphosis and turn to air pirates. Like shining arrows they fly through midge swarms and catch midges by spiky legs. However they become victims of insectivorous birds. Their most terrible enemy is swallow-looker, equal to many dragonflies in speed. Sparkling with oculate spots on long tail feathers, swallow-looker male flies above little marsh and catches a small dragonfly – one of numerous ones hovering above water. In heat of summer at the majority of these birds there is one care of paramount significance: to feed posterity. Having made a graceful turn in air, bird flies to nest. Having hung in air for one second, swallow-looker male clings by claws to an entrance. Having felt a push, nestlings quicken and open wide mouths. But there is only one dragonfly, and it at once disappears in the nearest mouth of nestling. The second nestling receives the lump of insects stuck together by saliva from parent’s craw, and the third and the fourth ones will come to wait while mum will return.
Swallow-lookers have their first and last brood in this season in their nest, and the breeding pair of mousebirds already started the second nesting cycle. Birds have carefully cleaned a hole, have thrown out the rests of the old litter teeming with parasites and have plunged again into parental cares, hatching by turns the second clutch in this season.
Across the plain deep stream with clear cold water flows. It is one of hundreds, and even of thousands of streams that begin in peat bogs or flow down from glaciers of the Central Antarctica in the summer. Its water is crystal-clear and cold. This is a fine place for breeding of insects. In Antarctic streams it is possible to find larvae of midges and local nonbiting chironomids. They breed in huge numbers here: mosquito larvae, being disturbed by anything, in large clouds jump out from silt, and midge larvae cover stones and underwater parts of plants like carpets. One species of Antarctic mousebirds has adapted to get food in water. It is a necktied mousebird, the close relative of white-throated mousebird. It is not able to dive and run on the bottom like dippers do, but has developed a special way of catching of these larvae. Necktied mousebird, dexterously jumping from stalk to stalk, moves far from the bank. Having chosen a place where the colony of midge larvae is seen, it moves on the stem nearest to it and moves down under water, seizing it by paws. The plumage of necktied mousebird is richly smeared with secretions of preen gland, and under water the bird looks silvery. Having inhaled at last, the bird quickly moves under water, and, not letting stem off, begins pecking small insect larvae quickly. When the inhaled air comes to an end, the bird rises, makes some breaths and dives again.
It is possible to find under water something larger than midge larvae. Mousebird is involved with movement at the stream bottom. Having gone down deeper a little, necktied mousebird sticks its beak into vegetative dust, and on the spot catches a dragonfly nymph trying to hide. Not wasting its force, it emerges like a cork, having let the stem off, and quickly gets out from the stream. With the impact against the ground it kills the nymph and tears it to some pieces. Having filled its craw, mousebird hides in grass: it has fledglings which have left the nest but still depend on parents.
Mousebird runs to its brood, being hidden from curious sights by sedge leaves. It hastens to the brood, being not suspected that it is bearing also danger to its posterity in addition to food. Falcon grackle, huge yellow-eyed male, has noticed this fussy bird, and now flies following it. In its mind this bird does not concede to crows, and the predator perfectly knows, where the bird gathered such amount of food may lead him. Mousebird runs out from sedge thickets and hastens to high cushion of one Antarctic graminoid. Here, between its stalks, four young necktied mousebirds hide. Having caught sight of the parent carrying food, they begin calling, thus showing to falcon grackle where it is possible to find easy prey. Predator falls upon grass bush where young mousebirds hide, but quick reflexes have saved tiny birds. Maybe, they are not able to fly, but they run excellently. While grackle flapped wings, having got stuck in grass, it had seen the several birdies jumped up in air high and immediately dived in grass. For those seconds when grackle folded its wings, mousebirds succeeded to get away. But hunting is not finished yet… Grackle has long legs, and sometimes it gets small prey by catching it up in run. At the wintering places in South America these grackles catch rodents in this way, chasing them in grass. Therefore grackle tries to overtake mousebirds in run. It has quite good chances: birds are young and still run not as quickly, as adults do. But mousebirds also have an advantage before the feathery robber: they are small and can run easily in places where the predator will squeeze hardly. Mousebirds hide in grass, intentionally choosing the thickest parts of it, but grackle does not recede. And mousebirds have one more trick in stock: they hide in sedge. Edges of sedge leaves are sharp and put unpleasant cuts, therefore the predatory bird recedes. Today mousebirds are lucky, but their life will not always be so successful. Once a predator would be lucky also, but not now. Therefore falcon grackle begins air hunt where it has a chance.
Swallow-looker nestlings develop quickly and leave nest in five weeks after eggs had been laid. But they not at once pass to independent flight, like swifts do, for example, but for about one week they are on parental care. In the beginning of second half of summer at the meadows of Antarctica it is possible to see broods of these birds perching on stalks of large grasses. Feathers on their wings and tails have not grown completely yet, therefore birds are not able to fly well. In case of an attack of falcon grackle young birds simply jump down in grass and hide there. But nevertheless falcon grackle still has a chance to prey them. It applies hunting tactics of hawks, attacking them from an ambush. The bird hides in bushes and chooses a brood of swallow-lookers perching as close, as possible. Having chosen prey, grackle rushes out of bush like a spring and tries to overtake birds before they will jump down in grass. Until the last second young swallow-lookers do not suspect about the danger threatening to them, and they hear alarm signal too late. One birds has delayed for some moments, and the grackle, flying above grass, has seized by beak the swallow-looker jumped down. Having shaken it up harshly, grackle kills its prey and flies up.
In reply to this attack in air the same events are played, that repeated for many times in other places and in other time: prey and predator change their roles. Having gathered to one numerous flock, swallow-lookers rush to the aggressor and attack it. Being alone, each of these birds would prefer to hide, but the number of congeners gives some impudence to them. They beat by wings the grackle carrying killed bird, and one swallow-looker even perches on its back and begins biting it, opening its wide mouth. Grackle shakes its head, makes sharp bends in air, trying to get rid of chasers. It hastens to bushes, folds its wings and dives into branches. Tender long-winged swallow-lookers can not continue their chase and fly out, having hovered for some time above this place.
When they fly away, falcon grackle appears from bushes. It managed to defend prey, and now it is an appropriate moment to have a meal. Having looked round, the bird instinctively beats its prey against the branch for some times and begins plucking its feathers. But fight for a meal is not won up to the end yet. When falcon grackle starts to tear meat and to eat prey, one more applicant appears. It not the congener, not a bird, and not a vertebrate animal at all. Very large Antarctic dragonfly with wings, looking as if they are smoked, expresses rather unambiguous interest to its prey. For the color and wingspan up to 18 cm it is fairly named as “black emperor”. Remarkable in its boldness, this dragonfly begins attacking the bird, trying to drive it away from prey. Falcon grackle tries to defend itself for any time and clicks its beak, but the dragonfly itself makes aggressive attacks, aiming its head and eyes. Being unable to constrain an onslaught of an insect, grackle recedes. Smell of meat attracts some more black-winged dragonflies of the same kind. Predatory insects eat the caught bird, from time to time flying up and hovering above the swallow-looker carcass. Grackle is cautiously mown on them, perching nearby. When on bird carcass only one dragonfly stays, bird musters up courage, takes its prey and gets away hastily in thickets of sedge. Having hidden from annoying persecutors, grackle begins eating greedy the rests of its prey. But the smell nevertheless gives it out, and one of these dragonflies lands on leaf next to the bird. However, it seems it will not come to expect more for a gratuitous entertainment: grackle swallows hasty the last piece of prey, then coughs, having choked with casually swallowed feather, and flies up – it needs to continue hunting.
The adult grackle can have a rest and a meal rather seldom: its nestlings have already left the nest and perch on its woven roof. They always have good appetite, and parents are almost constantly occupied with food extraction. When any parent lands on nest roof, juveniles literally attack it, eliciting for food. But their carefree time comes to an end, and soon young birds will be compelled to search for food by themselves. And they will fly out to wintering area quite independently.
Summer gradually comes to an end. The first sign of it is the sun, which for the first time for some weeks goes under, and day is replaced by night for a while. At this time it becomes especially appreciable that Antarctica is still at the South Pole – night is rather cold. Swallow-lookers perch on branches of bushes, and sleep, having nestled to each other in rows numbering some birds – it is warmer for them in this way. In the morning they feel themselves hungry, but they have not succeed to have a meal at once – insects still keep in grass, not having warmed up. Only after one more hour swallow-lookers succeed to catch them in amount enough to be sated.
Nestlings of the second brood of mousebirds have already grown up and can walk in hole. There are four of them – this year summer is plentiful, and female had laid more eggs, than usually. Having received from mum a portion of insects, they get outside to get warm in sunlight. Having fluffed feathers, they stand in patch of sunlight, having gathered in group and having slightly opened scanty winglets. Suddenly somewhere not far from them alarm call of one mousebirs is heard. Nestlings immediately protect themselves as they can: three ones bunch together and freeze, having dropped to the ground, and the fourth nestling had managed to rush to paternal hole and to hide there. They had done it just in time: above the grass falcon grackle flies by low, looking out for prey. It has not noticed these nestlings, and this time they are lucky. But it is not known, where and when the predator will succeed…
Flocks of swallow-lookers hover in the sky. From time to time falcon grackle appears in air, frightening them with its presence. But now it is not so terrible to them: young birds became completely independent, and now do not concede in speed to adults, and adults are not attached to nests near which the predator arranged an ambush sometimes. Swallow-lookers fly much faster than falcon grackle. It happens that flock of swallow-lookers, being numerous enough, may attack falcon grackle and frighten it off from its favourite site with their turns in air. Swallow-lookers do not like to risk in vain: nesting season has passed, and the instinct of self-preservation overcomes the parental one. Therefore they attack the grackle, only being completely sure in their own superiority.
Day by day weather becomes cooler. And there comes the day when on grass cold dew falls. It is a signal – there comes an autumn, and it is a time to take care of wintering. Swallow-lookers return here among the last ones, but fly out to the warm north the very first. They vanish literally in one night. There is no long parting with the land which is the only known one for young birds. There are no farewell calls, there are no long preparations. The sun simply rises once, and the sky is quite clean: birds vanished till the next spring. They are literally gone with the wind: having flied up, birds get in wind stream blowing from the pole. Using it, they quickly cross the ocean and reach South America.
Some more weeks passed. Swallow-lookers already catch midges above wetlands
off Amazon river and its tributaries for a long time, and in Antarctica life
becomes harder and harder.
Weather becomes colder and colder, and at night on grass unpleasant cold dew falls. Mousebirds of the second generation have already abandoned their parents for a long time, and the parental pair had broken up right after that. Young birds feed together for now, running in group in sedge thickets. It is not four, but only three of them now: one young mousebird had been caught by falcon grackle.
Autumn is a short holiday of life in rigorous and parsimonious Antarctica. It is a time of abundance of food when it is possible to find enough forage without efforts – berries, seeds and last insects.
When slanting sun’s rays fell upon withering meadows of Antarctica, the dry grass has begun to move, and from it moss leaf beetle appeared. This large beetle had emerged recently, and now it searches for suitable place for wintering. To fly up, it should get warm well in sunlight. For this purpose the beetle creeps higher on grass stalk, finding a warmer place. Time is needed to be warmed up and fly, and it seems, beetle has none of it: from under sedge leaves young white-throated mousebird appears, catches it and cracks by beak with a loud crunch. But instead of meal the little bird receives troubles only: red colouring of legs of this beetle warns that it is poisonous. Having felt its heat, mousebird began shaking its head to obviate it somehow, and then began pecking and spitting out the ground. It will be a lesson to it, and the death of one beetle will save some more of its relatives: the bird will remember a bright coloring of its legs, and the next time would cease to touch it. But it can happen so, that it will not have the next chance. During the unsuccessful tasting of the beetle it loses vigilance for some minutes, and it is a mistake. Somewhere in the side alarm squeak of one young mousebird is heard, and two more birds run by, and they are followed by falcon grackle running fast and having slightly opened its wings. It is young yet: predator has brown ordinary-looking juvenile plumage and beak lack of frightening hook at the tip. Eyes of the bird gleam yellow: it is young male, and when the maturity will come, magnificent yellow feathery “glasses” will grow at this one. But now it takes the first steps to position of a dominant predator of the Antarctic meadows, trying to hunt independently. Parents do not take care of it as intensively, as before, and sometimes drive it away from their prey at all; therefore the bird already should expect more for itself, than on scraps of parent’s meal.
In autumn young falcon grackles perfect their hunting tricks. Birds have found young mousebirds in grass, and now chase them, fluttering sometimes from one place to another to prevent their escape. Having formed a row, predators hunt mousebirds in front of themselves, gradually bringing together ends of their row. Mousebirds try to avoid it desperately, scurrying in grass and trying to break through the row of predators. One of them managed to slip under the legs of predator, and another had got in beak of young grackle, but had escaped, having left to it only a pinch of its feathers. Eventually one of these birds appeared surrounded. It unsuccessfully tries to run away, but predators have already closed their ring. Grackles do not let it out and attack it, trying to peck the bird trying to avoid their strikes. One by one they put mousebird some wounds by beaks, and, at last, peck it to death. But the result of hunting is too insignificant, and they have almost nothing to share. Probably, having understood it, young male grabs the tormented carcass and escapes at full speed to the nearest bushes, and other participants of start in pursuit of it, scaring away numerous mousebirds they quite could catch by themselves.
Day after day weather becomes colder and colder. Grass turns yellow and fades, insects gradually disappear. In one more cold Antarctic morning last “black emperor” dragonflies hang on yellow stalks of sedges. They turn backs to the sun, trying to be warmed in its poor beams enough to fly up. But their time in this season comes to an end, and from hunters they turn to prey. Falcon grackle has found them, and now it pecks dragonflies one by one, tears them and eats. The wind only carries away to grass their translucent wings.
In air only some small damselflies fly, but they are more carried by wind, rather than fly by themselves. It became too cold for them, and once in the morning they simply can’t fly up. But warm-blooded birds still live active life though for some of them weather becomes not too suitable. Falcon grackles one by one or in small flocks migrate to South America. Having crossed Drake Passage, they will spend winter in a pampas, hunting rodents and small opossums. But some birds still hunt in faded grass, trying to find mousebirds. The grass already lies flat and cannot hide even such small bird. Now even adult grackles wander in grass, as if recalling skills of driven hunt that had been practiced in youth, right after they left the nest. Birds stir grass hummocks, driving away mousebirds hidden there. Small birds run away, searching for escape in sedges, and everywhere at the plain their alarm calls revoice each other. Escaping from predators, they use one old, but well job-proved trick – sedge leaves still can cut legs of predator up to blood, and falcon grackle reluctantly pursues the birds hidden in sedge. When one grackle chases mousebirds, trying to overtake them, one bird escapes from it, having dived into the old hole. The predator does not notice its cunning, and walks by absolutely near to hidden mousebird which may be pulled out from the hole easily and eaten. Grackle noticed that some mousebirds whisked in sprawling hummock of sedge and now tries to expel birds from their refuge. It cautiously moves leaves apart by paws and beak, but mousebirds hides even deeper into the thickets. It doesn’t succeed to seize them – the edges of sedge leaves are rigid and make painful cuts. Having tormented itself for a certain time, the bird flies up and begins search for easier prey. And mousebirds, having convinced that danger is out, cautiously leave sedge and begin feeding.
Grackles are only temporary inhabitants of Antarctica, but mousebirds live here the year round. When last of these predators fly out, mousebirds can fearlessly scurry in grass, searching for seeds and the insects hidden for wintering. But their holiday lasts not for long: from polar glaciers the wind blows, carrying dull continuous clouds from which sleet falls.
Now the most dangerous inhabitants of this continent are only sea birds which do not leave sea coasts. Predatory bird-catching sundews have faded a long time ago and now do not represent threat for mousebirds, and sometimes birds succeed even to find and to peck large sweetish tuber of this plant.
But in winter two most terrible enemies which can overtake any live creature anywhere – these are cold and famine. Winter is a time when death rate among mousebirds reaches a maximum. No more than one third of the number of birds lived in late autumn will survive to the next spring.
Winter life of mousebirds is hidden from curious sights by thick layer of snow. In winter mousebirds will dig indefatigably a system of tunnels under snow, searching for poor forage. Going hungry, they will even peck corpses of the dead congeners. But sooner or later new spring will come, and those who can survive, will get a reward: their better qualities will be embodied in their posterity.
white-throated mousebird (Musornis leucofrons)
Order: Passerine birds (Passeriformes)
Family: Mousebirds (Musornitidae)
Habitat: grass and sedge thickets of Antarctica.
Picture by Arseny Zolotnikov
The Antarctic continent at the beginning of Neocene gradually
began to free of ice. Two factors had promoted it: the general Earth climate
warming and the movement of continent to the north: Antarctica had gradually
shifted towards Meganesia which had also moved to the north – to equator. At
northern coast of Antarctica free of ice shield the fauna of new terrestrial
species of animals began development. It is made of descendants of species managed
to get to this continent by air: of birds, insects and small spiders. Settlers
had arrived to Antarctica mostly from South America and Australia. At the sea
coast of Antarctica sea birds feeding on seafood dominate, but far from continents
the original empire of small flightless birds appeared; among them mousebirds,
feathered analogues of rodents, are most numerous.
Passerine birds had almost never lost flight ability. Perhaps, the unique exception had been New Zealand bush wren (Tavaresia) lived at small Stevens Island in Cook Strait and extinct in historical time. But in Neocene flightless passerine birds became much more diverse: in Antarctica the whole separate family of mousebirds had appeared. Tapacolo birds (Rhynocryptidae), which reluctantly flied but spent much time on the ground and run well and inhabited in Holocene epoch the far south of South America, had been ancestors of species of this family.
The most widespread species of family is Antarctic white-throated mousebird, bird about 10 cm long with long tail (the length of two middle feathers is equal to length of body and head). Body at all mousebird species has very strong constitution: large head, short strong neck, stumpy body and rather long legs. Head of white-throated mousebirds is equipped with strong crushing beak: ration of this species consists mainly of seeds of sedges and giant graminoids making grass cover of Antarctic Region. Mousebirds scurry dexterously under bushes of grasses on strong legs with well advanced toes and short claws, gathering seeds had fallen on the ground. They also are able to clamber and jump on stalks of graminoids, pecking ears. The vegetative food is supplemented with insects and their larvae.
Wings of all species of Antarctic mousebirds are not adapted to flight: they are rather weak and their primary feathers are short and have soft vanes. Wings of males are colored rather brightly from below: they are used in courtship displays. At males of white-throated mousebirds inner side of wings is bright pink.
Contour feathers of mousebirds are adapted to endure Antarctic winters. Feathers are very rich, their vanes are soft, and the down part of feather accounts about half of its length.
The feathering of mousebirds is colored modestly to preserve birds against predators attacking from above: the only predators of the continent are other birds. But each species has bright color spots and strips which help birds to identify representatives of their own species. At Antarctic white-throated mousebirds body has brownish background color with longitudinal yellowish strokes on back and wings, and on throat and chest there is an extensive area of white feathers shaded with dark brown feathers on edges. The beak of white-throated mousebird is colored brown, but males have narrow red strip on its basis.
In winter mousebirds dig with legs and beak extended burrows to the surface of ground and dig out withered leaves in searches of seeds and hibernating insects. Mousebirds living near the ocean coast leave from under snow in winter to peck a carcass of any sea bird dead from famine and cold.
Courtship displays at mousebirds begin in spring, when long polar night ends, but snow is not completely thawn yet. Males get on bushes of faded grass and display feathering, raising wings up and showing their bright inside. From afar it seems, as if in grass flame tips burn. Calling females, males utter loud courtship call – lingering high-pitched shrill. Females come nearer to thickets, not showing themselves so obviously, and answer appeals of males by silent abrupt sounds. Pair at these birds is formed to one breeding season, but for this time birds have time to make two clutches and to bring up posterity.
The clutch of 3-4 white eggs is hidden in shallow hole dug by the pair of mousebirds in common. Frequently they renew the found old hole. The entrance of nesting hole is disguised among bushes of graminoids or sedge. Near the nest mousebirds are very cautious; birds frequently reach the nest entrance in roundabout ways to not give away its location to probable predators. Both parents hatch eggs; nestlings appear in two weeks. They are covered with rich down, but are blind and helpless. Nestlings grow intensively; parents feed them for 3 weeks in nest and after young birds leave it, finish feeding for about one week. Right after the juveniles leave nest and become independent, the breeding pair begins new nesting.
Close species live in Antarctica:
Striped mousebird (Musornis fasciatus) is similar to white-throated mousebird in body shape, but its feathering is brown with yellowish cross strips. Beak of this species is short and wide: this bird eats mainly hard seeds of sedges and invertebrates with firm covers. Usually striped mousebirds eat beetles, but the populations living at sea coast may feed on crustaceans – sea kinds of scuds. Thus birds try to drive them off from water and to drive in grass where crustaceans can’t escape from chasing with the help of jumps.
At males on sides of head feathers are longer, than at females: during the courtship displays the male spreads them asides and opens like a fan, exaggerating visually its own size. Under male’s wings there are bright orange feathers. Males display them perching one by one on dried up stalks of sedge. Each male occupies the territory of about 20 meters in diameter, declaring its rights to it with the help of buzzing calls and demonstrations of wing insides.
Necktied, or black-bearded mousebird (Musornis melanobarba) is closely related to white-throated mousebird, but at the male of this species there is a longitudinal strip of lengthened black feathers on chest. In courtship displays male rises head up and such “beard” protrudes forward. Shaking head from side to side, male involves females.
This species lives in marshy plains near the Antarctic glaciers. Necktied mousebirds eat mainly insects, and can come into water of shallow bogs, searching for larvae of mosquitoes and midges. They are not able to swim actively, but go down under water to small depth, clinging by paws for stalks of canes. Holding the breath for some seconds, they peck larvae, and then unclench paws, emerging on water surface as if a cork. In winter, when it is impossible to find the necessary quantity of insects, they pass to vegetative forage, searching seeds under snow.
swallow-looker (Chelidopteron graminophilus)
Order: Passerine birds (Passeriformes)
Family: False swallows (Neochelidonidae)
Habitat: grass and sedge thickets of Antarctica.
Picture by FanboyPhilosopher
In Neocene the climate of Antarctic Region became much better,
than it had been before it at the end of Holocene. The significant part of continent
was released from the ice cover, and in these places life is plentifully developed.
Basically the vegetative cover of Antarctica is presented by various communities
of graminoids and sedges. But near to glacial board where there is an underground
long-term frozen ground, the zone of moss bogs alternating with heights occupied
by xerophilous grasses is stretched.
Bogs of Antarctica are the favorable place for breeding of various two-winged insects: midges and mosquitoes. The majority of them does not concern to blood-sucking species: Antarctica is not settled yet by large animals on which flights of winged bloodsuckers could be fed. But the largest local inhabitants, sea birds, constantly are exposed to attacks of winged torturers.
Such abundance of insects both with a relative rarity of local predators has made Antarctica a fine place for life of small insectivorous birds. While in Antarctica polar summer reigns, and the sun shines all day and night, insectivorous birds are eaten off and hatch posterity.
But boundless meadows and bogs of Antarctica are the paradise for elite: the continent is separated from other parts of the world by wide passages, and such situation will prolong still many tens millions years. Therefore only the most tireless flyer can get here. One of insectivorous birds prospering in Antarctica is the small Antarctic swallow-looker, in literal sense the master of high flight.
This bird of passage is the descendant of American species Scissor-tailed Flycatcher (Tyrannus (Muscivora) forficatus). The adaptation to active long-term flight had made the first rate flyer of this bird. Streamline body shape, long pointed wings and straight narrow tail testify to excellent flying abilities of Antarctic swallow-looker. Two border feathers in tail are very long and wide – with their help bird can make sharp turns in air, chasing insects.
Swallow-looker has short but tenacious paws. This bird can move on the ground, and even fly up from flat surface (for example, swifts can not do it), but nevertheless it feels like more freely in air. In flight birds can even have a sleep a little: at dreaming bird different sites of brain have a rest by turns, as at dolphins. Only birds hatching eggs in nest can fall asleep deeper.
The appropriate “hunting equipment” is necessary for catching insects, and ancestors of the swallow-looker have got it. At swallow-looker there is short and weak beak, but the mouth cut is very wide, coming over back edge of large eyes. Sight is sharp, almost binocular. The feature of visual perception of swallow-looker is the enhanced attention to tiny contrast objects (in this sense the bird is similar to frog at which the same feature is developed).
For catching insects swallow-looker has the adaptation increasing trapping abilities: original “beard” of thin feathers on edge of the bottom jaw. During the feeding bird protrudes these feathers forward, forcing midges down from vegetation by them.
The basic food of swallow-looker includes mosquitoes and midges plentifully breeding in bogs of Antarctic Region.
Male and female of this species well differ by colouring. At males head is covered on crown and nape with crimson-red feathers, well appreciable from afar. At the female head is smoky-gray. The body of birds of both genders is colored grey from above, and stomach is white. On tips of long tail feathers at swallow-looker black spots with iridescent dark blue oculus in the middle had appeared. Such spots help to distract attention of possible predator from vital parts of body of bird.
Swallow-lookers spend winter (in Southern hemisphere – from the end of May on the beginning of September) in South America: they reach northern borders of pampas and zone of dry woods. But they intend to fly to Antarctica late enough: it must pass some time for appearing of clouds of winged insects.
At once on arrival from places of wintering courtship rituals begin. Breeding rate at Antarctic swallow-lookers is insignificant: for summer there is only one hatch at them. It is connected with the short time of especial plenty of insects – only about two months till the year.
In clutch of swallow-lookers it happens 5 – 6 bluish-white eggs. Male and female hatch them alternately though the most part of time the female hatches eggs. At this time male protects fodder territory from competitors.
The incubating lasts about two weeks; nestlings hatch blind, covered with thin down. They quickly grow, and leave nest at the age of three weeks. At this time they are completely fledged, and only two feathers in tail and long primary feathers continue to grow. After leaving the nest the significant part of fledglings perishes from feathered predators of Antarctic Region. About one week parents finish feeding of fledglings; then parents abandon them and pairs break up. Young and adult birds form numerous flocks: it is easier so to defend from predators. At this time borders of individual sites, formed till the nesting period, disappear, and birds freely move above bogs of Antarctic Region, gathering for lodging for the night in dense bushes.
Antarctic swallow-looker departs to the wintering too early – at first signs of cold snap. From this time the amount of basic forage of birds, small two-winged flies, becomes insufficient for normal life of these birds. Flocks of swallow-lookers migrate very originally: at flight they rise in top layers of air, and fly ocean with fair wind.
grackle (Falconicterus antarcticus)
Order: Passerine birds (Passeriformes)
Family: Grackles, or American orioles (Icteridae)
Habitat: grass thickets of Antarctica.
The family to which this bird belongs is settled in New World from far north up to far south. Representatives of family eat both vegetative and animal food; therefore occurrence of almost completely carnivorous species among them is not so unusual event. Some species of grackles lived in Holocene had willingly eat the food of animal origin. In conditions of temperate climate of northern coast of Antarctica where predatory birds had not settled, one representative of grackle family – falcon grackle – had occupied their ecological niche.
Falcon grackle is almost completely carnivorous bird equal to young crow in size. It is an ecological analogue of corvine birds; vegetative food makes very small part of its diet. Predatory habits have left a characteristic trace in the shape of bird: beak of falcon grackle is wide and rather short, and has bent tip (it is a little similar to beak of butcherbird). Wings of bird are pointed and adapted to fast flight. Tail is long with small hotch at back edge. Legs of this bird are long and strong: tracking down the catch, in case of necessity falcon grackle may run fast on the ground.
This species has clearly expressed sexual dimorphism in colouring and size: male is larger than female, black with yellow back and rings around of eyes, and on its head there is a small crest. An iris of eyes at the male is yellow too. At females colouring is much more modest: background colouring of body is black, wings are rusty-brown, eyes are black, yellow feathers around of eyes are absent.
Like the most part of Antarctic birds, falcon grackle is a bird of passage. It migrates to the continent early, stays here for rather long time and returns to the wintering areas only at the time of first snowfalls. This species spends winter in South America (Tierra del Fuego), moving far to the north along mountain ridges.
The majority of grackles of tropical latitudes are polydins. But in conditions of rather poor resources of Antarctica falcon grackles became monodins: it permits the parental pair to feed up posterity successfully. The family is formed to one breeding season. Courtship rituals begin at once after the returning from wintering. The male takes a place convenient for nesting (usually in thickets of undersized bushes) and starts singing, involving the female. Voice of this bird sounds like loud single calls.
When in his field of view the “beautiful stranger” appears, the male behaves quite differently: he starts to tear blades of grass and leaves by beak, and skips back and forth in bushes, appealingly glancing at the female. If she likes the male and his possession, she accepts the torn blade of grass or leaf from his beak – it is a sign of readiness for nest building.
Falcon grackles have inherited building skills characteristic for representatives of this family. The pair of birds makes in branches of bushes spherical nest with short “sleeve” entrance of last year's grass and leaves of sedge torn to strips.
This species has rather slow rate of reproduction: per one year breeding pair has only one hatch of 2-4 nestlings. Female hatches white eggs within approximately 20 days. Male feeds her the whole time and also protects vicinities of nest. At this time it attacks on live creatures of any size approached too close to the nest. The bird swoops on newcomers with loud abrupt calls, trying to peck their heads. Also effective means of protection are to hit in enemies with feces as some species of small birds of Holocene epoch did it.
Nestlings hatch blind and covered with thin grey down. They stay in nest for about six weeks, and after leaving the nest parents finish their feeding for about one month. Birds of the first year of life have juvenile brown feathering and short straight beaks. Becoming mature they get typical colouring of adult birds, beaks become bent, and the grackles begin eating not only large insects, but also small vertebrates and carrion.
Long “childhood” permits to young birds to seize skills of hunting, observing for adult birds and playing. It is especially curious to observe how young birds from one or two hatches play “cat-and-mouse” with small local flightless mousebirds. Having driven out several tiny birds from thickets to open place, young falcon grackles surround them and begin driving back and forth, frightening them by cries and sharp attacks. Frequently quick mousebirds succeed to slip away from juvenile feathered predators, but later the hunting skills of young falcon grackles increase, and game gradually passes to true hunting.
Cannibalism, usual at carnivorous birds of Holocene – owls and true birds of prey – is rarity for the falcon grackle: only fledglings at lack of food may peck and eat the weakest bird in hatch.
By its habits the falcon grackle resembles the kestrel a little: tracking down its prey in dense grass, it frequently hovers in air, quivering its wings. Flight of this bird is fast and maneuverable. Sometimes falcon grackle hunts even fast flying birds of Antarctica, chasing them in air. If predatory birds of Falconiformes order put the solving impact to pursued prey with the help of back toe armed with large claw, falcon grackle forces down its prey in air by beak. This species may hunt on the ground, chasing mousebirds in thickets of sedge and grassess. Frequently falcon grackles may be seen solitarily or in small groups at the sea coast where these birds eat dead fish, gather mollusks and crustaceans. Sometimes falcon grackle steals eggs and nestlings in colonies of sea birds, and also eats corpses of adult birds and nestlings, acting as the original “sanitary service”.
leaf beetle (Antarctomela bryophagus)
Order: Beetles (Coleoptera)
Family: Leaf beetles (Chrysomelidae)
Habitat: Antarctica, moss fields near the glacier.
Picture by Alexey Tatarinov
In Antarctic Region of Neocene epoch at the areas, from which
the glacier has receded, rather dense vegetation had developed. It was made
of plants which seeds had been brought to Antarctica by winds from the nearest
landmasses: from South America and New Zealand. Here it is possible to meet
graminoids, sedges and some plants of other botanical families. But the very
first plants which mastered this continent and have reached the certain success
here were the mosses which have got to Antarctica as spores. These unpretentious
and slowly growing plants at one stage of formation of the Antarctic flora have
formed almost continuous cover on land free of glacier, avoiding only salted
coastal soils. Later, when floral plants have got accustomed at this inhospitable
land, mosses have receded to edges of the glacier, having formed around of it
a zone of mossy bogs. It is the most ancient ecosystem of Antarctica after clearing
of the part of continent of glacial shield. In these areas animals – the direct
descendants of the first settlers of Antarctica – had also kept. Among the first
colonists there was one species of leaf beetle whose larvae could pass to feeding
on the lower spore-bearing plants – mosses. It became an ancestor of Neocene
moss leaf beetle of Antarctica.
Formerly even Charles Darwin has noticed that at the islands constantly blown by strong ocean winds insects either fly very well, or do not fly at all. Moss leaf beetle from Antarctica represents a live illustration to this observation. It is excellently adapted to life in conditions of rigorous cold climate. Body of this beetle, as opposed to many representatives of its order, is narrow and long (length is up to 4 cm at width is only about 1 centimeter). Wings of moss leaf beetle are strong – this beetle is excellent flyer and can resist in flight to the strong winds constantly blowing from the Antarctic glacial shield. It has no reasons to be a slow homebody: fodder plants of this beetle – mosses – grow slowly, and it must migrate within the borders of narrow strip of cold moss bogs to breed and not to exhaust the stocks of forage.
Elytra of moss leaf beetle are covered with black bristles. Head and thorax at this beetle are also black. In general, black colouring and plentiful hair on covers are characteristic features for Antarctic insects. It gives them an opportunity to be warmed in sun rays easier and to cool down slower. On legs of moss leaf beetle cross strips of red color are appreciable – it is a warning to local predators that this insect is inedible: in beetle’s hemolymph bitter substances are accumulated. At males antennae are also colored bright red – it is a signal attracting females. Females of this species are larger and wider relatively to males. They are able to fly, but do it reluctantly – only for the sake of search of places for egg laying. They have strongly advanced olfactory receptors on antennae: with their help females find thickets of moss suitable for their larvae feeding.
Young beetles leave their winter shelters when snow already has almost melted. For approximately two weeks, while polar summer heats more and more, they feed on green parts of various plants, and then begin breeding. Males fly above wetlands intensively at any time of day, searching for females by smell.
Right after pairing female moves to searches of thickets of moss of the necessary species. Moss leaf beetles prefer feeding on peat mosses, but at lack of this food pass to other species of leafy mosses and even eat lichens. These beetles lay eggs in small portions of 10-12 ones at rather great distance from each other. During the summer female can make up to 10 such clutches with breaks in 3-4 days. Egg incubation passes quickly, that is promoted by long and rather warm polar day.
Larva is feeding on moss secretively. It keeps in vertical position between moss stalks, hiding inside a moss cushion in case of danger. Its sight is badly advanced, but sensitive hairs on head feel movements of air keenly, allowing it to define the size of moving objects around. The body of larva is colored green, because through transparent body cover contents of intestines is visible; head is black. By the end of polar summer larva grows to the length 5 cm and begins preparing to metamorphosis. Usually larvae of early hatches pupate and transform to adult beetles in the same year, and spend winter already at the imago stage. Larvae of late clutches winter as pupae, and adult beetles appear in spring of the next year.
sundew (Droserophyllum ornithivorum)
Order: Saxifragales (Saxifragales)
Family: Sundews (Droseraceae)
Habitat: marshlands of Antarctica.
Ecosystems of Antarctica had formed very slowly, and they are strongly impoverished in comparison with surrounding islands and continents. Not any kind of live creatures could overpass hundreds of kilometers above the sea to land on inhospitable cold continent. Even in warm Neocene in the center of Antarctica the vast glacier remains, influencing a climate of this continent. These two factors explain relative scarcity of Antarctic flora and fauna. But in such inhospitable and isolated world not numerous successful migrants have found a place for the life, deprived a competition and giving set of opportunities for evolution. In Antarctica some ecological niches appeared occupied by live creatures absolutely unexpected in such roles. As smaller predatory beasts have failed to invade this island continent, their place one interesting carnivorous plant of sundew family has occupied.
Bird-catching sundew growing on marshy soils of Antarctica is very large representative of its family. Usually sundews growing in marshes of temperate latitudes are very insignificant, and in tropics they are much larger. But in conditions of Antarctica, out of competition with predators of vertebrate stock, it became favourable to these plants to catch rather sizeable prey: large insects and even small ground-dwelling birds. So natural selection had caused the appearing of large species of sundew. Its ancestor most likely is one of South African species of sundews, whose seeds have got to Antarctica with the help of wind, or, less probable, with birds of passage.
Leaves of this species of plants are long, ribbon-like (the length of leaf reaches 50-70 cm at width of about 3-4 cm) on strong short leafstalks; they form the sprawling crown. On surface of leaf the main hunting weapon is located – glands on long pedicles, secreting viscous sticky liquid. If the small animal would touch such gland, from it the liquid is sprayed out, which at contact with air turns to similarity of rubber. Usually after such meeting with a plant the possible prey distracts for some seconds and can easily touch other sticky glands.
Such smart trap would be the useless adaptation if the plant is not skillful to pay attention of possible prey to itself. Large lilac flowers blossoming on long flowerstalks in the middle of the rosette of the plant involve many pollinator insects. And for some of them visit to the flower of sundew may finish not so good: nectar has intoxicating properties, and the insects not capable to neutralize its action by special enzyme lose ability to fly for any time. The insects drugged by nectar fall in the center of rosette lack of trapping leaves. For some time they creep under flowers, and then recover and fly out. But until this moment they just serve as bait for possible prey of bird-catching sundew. Small birds (more often local flightless mousebirds) and predatory insects involved with fallen insects get in trap. They try to reach helpless prey and are quite able to touch killing leaf casually.
Movements of the animal which has stuck to leaf serves as stimulant for a plant, and impels its hunting reaction. The leaf to which the prey has stuck curls into spiral, compressing the trapped animal in coils. More the prey moves, tighter leaf coils curl and more digestive juice is secreting. Eventually prey either is choked in “embraces” of this plant, or it appears digested alive by the enzymes secreted by leaf. Only rather firm parts – bones, feathers or chitinous shell – remain of it. Small prey like insects and spiders is also killed by bird-catching sundew with the help of alkaloids which are present in its digestive juice.
During the digestion of prey in leaf the irreversible physiological changes take place – there is an active outflow of organic substances to the stalk. After digestion of prey the leaf of this plant turns more and more flabby, as if it exhausts itself, and eventually dies off. But to replace it a new leaf quickly develops.
Flowers of bird-catching sundew serve not only for attraction of various animals to the plant. Their main function is reproduction. The pollinated flower develops to fruit – dry pod filled with tiny seeds. The fruit is moved then to the height of more than one meter on long pedicel and dehisces. Wind carries tiny seeds of sundew to new habitats. Due to the help of wind ancestors of this plant managed to settle Antarctica separated from other continents and to find the new native land here.
Nutrients from the caught prey are stored in stalk – large turnip-like tuber covered with the rests of dead leaves. In spring it sprouts on ground surface, grows thick and sometimes gives lateral shoots of which new rosettes form. Closer to winter roots drag it into the depth of ground, under the layer of vegetative litter where frosts do not threaten to it. The next season of growth new tuber is formed atop of last year’s one. In winter this sundew may “change roles” with local mousebirds – they willingly dig out and peck tubers of this plant. But it does not cause the great damage to sundew: if the main bud is damaged, plant will give some lateral sprouts.