G L Khajuria
Aristotle, the world renowned Philospher had more than two thousand years back had known how the Avian (Bird) migrate with seasonal changes but in fact it was in Mazzy, 1822 a day of bewilderedness for ornithologist that during this period they observed that a stork with its neck pierced was caught in Mecklenburg, Germany. In fact this stork with arrow had come from Africa and established for the migration though the fact goes that there are references in Sanskrit, by the Greek Philospher in the old testament and allied scriptures . In line with supporting fact, The German emperor Freidrich (1194-1250 AD) Observed South bound flights of bird crossing Meditarranian sea during winter.
The migration of birds is normally effected with the change of season and the birds have the record if flying over thousand of km and find the same locations where they had built their nests or habitats a year before. Why do birds migrate is a matter of mystery. After deep thought, it was established by the ornithologist that the migration triggered is to escape from cold, seek food and to choose new breeding grounds. And of all these birds, the most ones are those who don’t feel eagerness of migration despite the impending cold or weather changes that take place.
Ornirthologists establish that out of around 8-10 thousand species of birds those inhabit this planet, two third are migratory amd strangest fact is that these fly too high mountaneous regions like that of Himalayas or so. The Siberian crane is a regular migratory bird from Siberia to India flying long and hazardous routes.
After a great deal of studies ornithologist have established that American golden ploru (pluriallis) flies from Aractic to South America covering a long stretch around 7000 kms or so. The Red -Throated humbing bird barely 10 inches of size flies about 2500 Kms from Canada to Florida and the swallow (Hirundspp) measuring about 10-15 cms migrates covering a distance around 7000 Kms from Europe to South Africa crossing over Atlantic. The Northern pintail duck (Anas acuta) and garany duck (Anas queiquedula) which breeds in the Siberian tundra and taiga cover long long distances during their migration.
Similarly, the birds inhabitating in Delhi zoo also migrate long distances with the change of climate for food and finding new ground apart from 1200 species which are spectacular and inspiring. The Bharatpur Bird Sanctuary is a paradise of magnificent birds and same is with wildfowl refuge in Rajasthan which is barely 26 sq Kms in area and much of its area is marshy, besides the cover of woods. It is no denying the fact that the domesticated pigeon can obviously find its way home after having been shifted to unknown strange place or location. Similarly, it was experimented with wild manx shearwater, taken from its nest off the sea coast of UK and released in Boston USA. Surprisingly enough, the bird returned or navigated or to say avigated to its original habitat. The avigation of birds have been studied using advanced technology like radar, keeping the birds in planetarium, putting bands of light metal etc and the studies have shown miraculous results.
Ornithologist have established that birds navigate not only with the help of sun but these also pursuit or take cue from the position of stars of night sky. The German biologist FA Scheneider established that the bird navigate with the help of sun in 1996.
Stephen T Emin, professor at cornell university conducted detail studies to ascertain as to how the bird could orient the visibility of stars correctly. In his experiment, he turned off the light in the planetarium where birds were kept. Emin and other observers found that the birds fluttered aimlessly revealing that they took the celestial bodies if sky is their guide.
The ornithologists are not in consonance with the outdated idea that the birds are guided by the Earth’s magnetic field or that of gravitational field. In the experiment so conducted, the birds were put in a strong magnetic field with magnified plates attached to their wings and resultantly revealed insensitiveness to electromagnetic field or the result were inconclusive.
According to some researches, the birds, however can synthesize a magnetic compound capable of indicating the earth’s magnetic field.
It is astonishing to note that the avians are capable of forecasting weather conditions and their changes. Studies on pigeons have shown astonishing result that these can see polarised light and ultraviolet light. The birds, in fact , can hear infrasound (noise in ultralow frequencies which carry vast varied distances). As a corollary, it has been attributed that birds do not live in sensory world as we human do.
The birds during the course of long distant migration are having very sharp and keen eyesight. Physiologically their body weight is low as the skeletal structure is hollow whereas the pectoral muscles are strong enough to take long flights. Besides, the respiratory system is well adopted to meet up their metabolic activities involved during their long in that distance flights.
(The author is former Dy Conservator of Forest)
