WINTER VISITORS
The world of bird migration
is ancient and fascinating. And a peep into it is engrossing.Bird migration can
be broadly defined as a seasonal journey made by birds. They make this journey
for various reasons, the primary one being climate, food availability and
habitat. Birds use migratory flying corridors known as “flyzways”, that span
many continents, mountain ranges, rivers and coastlines. Research into their
migration shows that they avoid geographical barriers and very large stretches
of water.“How do they know where to go and when to go?” is an oft asked
question among people as they sight the arrival or departure of the migratory
birds. It has now been discovered that these routes may be genetically
programmed into the birds or else it was learned and mastered over the years of
flying.It has been found that birds fly at different altitudes during their
long journey. According to an expedition team in the Himalayas, skeletons of
the pin-tail and Black-tailed Godwit and Bar-headed Geese have been found in
the Himalayas. It is said that sea birds fly low over water and rise to a
greater altitude when over land.
Bird sightings were made
about 3,000 years ago by Greek poets Homer, Hesiod and Aristotle.
Muththappulavar, a poet from Madurai, wrote about the migrating white storks
known as — Valasai.
The Bible too has references to bird migration.“Does the hawk take flight by
your wisdom and spread his wings toward the south?” (Job 39:26)Resident
migratory birds build nests and breed in India, whereas migratory birds come
visiting in search of food.With the approach of winter, day light wanes and
birds find it difficult to feed. Food is important to have a healthy
reproductive system. So, they fly to warmer climes, feed well and when they
know that it is time to fly back home, they leave. This is the reason why
migratory birds do not build nests and breed in their host country.“Another
special feature to be noticed during these months is the breeding plumage. When
they are flying in, they are normally dressed in rather drab colours. During
the breeding time, they are decked up in flamboyant colours,” says Mr.
Thirunaranan, of Nature Trust, Chennai. He points out that Vedanthangal and
Koondankulam in South India are hospitable places for the birds as regards to
food and breeding. Vedanthangal especially has 22 lakes around it.The
Bar-tailed Godwit is known for the longest known non-stop migration of any
species – it flies up to about 10,200 kms.
However, all is not well in
the avian world. Climatic changes and global warming have played a heavy hand and
there are cases of overstays. Another serious problem faced by migrating birds
is that of poaching and hunting on their stop overs. For example, the
population of the Siberian Cranes declined due to hunting when they broke
journey in Afghanistan and Central Asia. According to reports, these birds were
last spotted at the Keoladeo National Park in 2002.Visitors of any species are
a joy to have around. We, as hosts must make it our responsibility, that they
are treated well before they leave, whether they be two-legged or feathered.
Can you imagine a world without the varied colours of our migrant- feathered
friends?
The Point Calimere Wildlife
and Bird Sanctuary in the Nagapattinam district, in South India, is a meeting
place for migratory water birds in India. In October, these water birds arrive
from the Rann of Kutch, Eastern Siberia, Northern Russia, Central Asia and
parts of Europe for their feeding season and begin their return journey in
January.These water birds include threatened species such as Spot-billed
Pelican, Nordmann's Greenshank, Spoonbill Sandpiper and Black-necked Stork.
Near-threatened species include Black-headed Ibis, Asian Dowitcher, Lesser
Flamingo, Spoonbill, Darter and Painted StorkResearchers at The Bombay Natural History
Society have captured, studied, ringed and released over 2,00,000 birds during
the course of several ornithological studies.
Prof. John Kurakar
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