Tour to Neocene
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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.
Bestiary |
Antarctic
white-throated mousebird (Musornis leucofrons)
Order: Passerine birds (Passeriformes)
Family: Mousebirds (Musornitidae)
Habitat: grass and sedge thickets of Antarctica.
Picture by Arseny Zolotnikov, colorization by Biolog
Initial 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.
Antarctic
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.
Falcon
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”.
Moss
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.
Herbary |
Bird-catching
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.