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Evolution of big birds in the Savannah

MANY people believed that, after creation the Earth’s surface was covered by water and there was no any living thing on it, about 3.5 billion years ago to make life possible on Earth, the almighty God accumulated the water mass in one place and named it ocean.

Ocean and sea is what scientists today are using the word Biosphere to represent the liquid mass which occupies the largest portion of the Earth, It’s believed that Biosphere came after the decrease of hot waves from the core centre which is also known as Asthenosphere and this lead into the emerging of Lithosphere or dry land with fertile soil which also supports lives of animals, plants and micro organisms.

Meanwhile fossils records indicate modern birds are the last remnants of dinosaurs whereby their ancestors evolved from a primitive birdlike very big reptile about 100 million years ago, with reference from Deoxyribonucleic acid or DNA tests, different researches on genetic materials of different species show that a dramatic diversification of this zoological class took place more than 65 million years ago.

History show that different species of birds evolved after a mass extinction event that killed most of plants and animals on Earth from about 75 to 65 million years ago. To cope with a fast changing environment, ancestors of modern birds were forced to develop different strategies which helped them to adapt new topography with strange or harsh weather condition.

An animal that failed to develop new adaptation strategies was forced into extinction just like terror bird which is the largest bird to ever live but got itself into troubles which wiped the whole population on earth about 2.5 million years ago.

Scientists say many factors contributed into the extinction of the terror bird but competition for hunting ground and attacks from larger predators wiped out from the ancient savannah the whole population of these mysterious creatures.

From the time of creation, the history of the world show that there are have been five different mass extinction which at difference time killed more than 90% of all existed species in the ancient world. Scientists believe that after the last particles of dust of the mass extinction fall on the ancient savannah, about 33 million years ago in a geological period called Oligocene, ancestors of the shoebill evolved on the earth.

Geologists, zoologists and other scientists believe that Oligocene is an important period on history of the world because changes on weather allowed the expansion of savannah which took place of ancient tropical forest.

Tropical forest which used to dominate a huge part of the world started to diminish while forcing most of its occupants to go into extinction after the last member of specie died because of hunger, thirsty or got killed by new predators.

Survival for those who are fit is the law of the jungle which has its roots in this period when hungry predators such as the shoebill evolved and started to hunt, kill and eat small and weaker birds and other small animals in the savannah.

The shoebill is a tall bird, it stands between 110 and 150 centimetres tall weighing from four to seven kilogrammes which are not heavy to powerful wings measuring about 260 centimetres, between 23 and 5.3 million years ago, climate changes which affected availability of wetland in the cradle land of these birds in Egypt forced ancestors of shoebill to migrate to South and Eastern parts of Africa.

To adapt life in the new environment, the body of ancient shoebill evolved with special mechanisms which include a long toe measuring about 17.6 centimetres which enable the bird to move along on wetlands, shoebill also adapted long and bigger bill which is used to open its way as a predator is pursuing a prey between long aquatic grasses but the mysterious looking bird was also given a sharp point on its mouth for rupturing.

During breeding season nests are built for about one square kilometres apart because breeding pairs use all their energy to defend territory measuring between two to four square kilometres, the shoebill’s feet are exceptionally large, with the middle toe reaching 16.8 to 18.5 cm (6.6 to 7.3 in) in length, likely assisting the species in its ability to stand on aquatic vegetation while hunting.

Evolution is a very complex process in the history of the world because about 23 million years ago when volcanic activities were cutting the Great Rift Valley in East Africa at the same time savannah ecosystem was expanding very fast, at that time when the shoebill concentrated into the wetlands, about ancestors of Secretary bird evolved in different parts of Africa and southern Europe.

Different scientific researches indicate that during those years temperature on surface of the world was moderate warm but took a sharp downturn to push the Antarctic ice sheet into its present size while opening more position for savannah grassland in the world.

Expansion of the savannah allowed secretary bird to flourish in Africa in the open grasslands in sub Saharan region but evolution helped this specie by shaping their bodies to meet a long period accompanied with dry weather condition.

From that time, nature gave secretary bird long legs measuring from 90 to 137 centimetres which make it the tallest among birds of prey in the modern savannah where this height is used to locate prey.

Secretary bird live by hunting and eating insects, mammals ranging in size from mice to hares and mongoose, crabs, lizards, snakes, tortoises, young birds, bird eggs, and sometimes dead animals killed in grass or bush fires.

In the savannah, Secretary birds catch prey by chasing it and striking with the sharp bill then swallowing small prey but large prey like snakes are stamped to death by using long legs, the secretary bird may sometime find its prey behind a raging wildfire where it may compete with Marabou stork another big bird which dwells in the savannah and wet lands of Africa south of Sahara.

The history of evolution in the savannah show this bird evolved in the grasslands between 5.3 and 2.5 million years ago at the time when temperature in the world rose rapidly which caused the disappearance of tropical forests and the spread of grasslands and savannah.

To live into this new but harsh condition, ancestors of Marabou stork went through adaptive morphological change which enabled them to work in hot weather of savannah in Africa, scientists say although before human’s eyes this bird may appear old fashioned and ugly but on its side the bald head is an adaptive feature which helped Marabou stork to live in the savannah.

Marabou stork live mostly by eating carrions from the dead animals in the savannah where its bald head penetrates deep into a carcass to enable the long bill to collect suitable parts but remain clean as it is being retrieved, at the time of food scarcity Marabou stork migrate into dumping areas of different cities and towns in Africa leaving the savannah for Ostrich the brave and courageous birds of the African grasslands.

Ostrich evolved into the savannah about 2.5 million years ago when the present continents of the world were in the same position during those days the world experienced a long period of El nino weather which originated from Pacific Ocean and Indian ocean.

It is believed that during this period the ice sheet on Mount Kilimanjaro was very huge but on the other side El Niño weather played a big role on the expansion of Maasai plains where one of the first generations of ostrich evolved, this bird is one of the most spread bird in Africa but mostly it dwells in the savannah of north, south and east Africa where national parks like Serengeti, Tarangire, Mkomazi and Ruaha are well known to harbor a good population of these birds in Tanzania.

Unlike other big birds, the shoebill is facing a big challenge from human’s economic activities which are destructing some wetlands in Africa, it is estimated that there are about 6,500 individuals in the wild.

Bird Life International an international organization which deal with conservation of birds has classified shoebill as a bird which is at risk, it says the only reasonable population is available in Democratic Republic of the Congo, Uganda, Zambia and Tanzania especially in Katavi, Mahale and Gombe national parks.

rstanslaus@yahoo.com

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Author: Reginald Stanislaus Matillya

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