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Nature and the Magnetic Compass-S.Ananthanarayanan

 

Nature and the magnetic compass

 

Blue light and a special protein help birds use the earth’s magnetism to find their way, says S.Ananthanarayanan.

 

 

That birds and many living organisms use the earth’s magnetic field to orient behaviour has been known for decades. But what could be the physical basis for such sensitivity has been elusive. One possibility is that birds have magnetic material embedded in their heads to help the bird sense magnetic force. The other theory is that the body has chemical agents which are sensitive to magnetism. Evidence has been found for both.

 

Pigeons follow nose

 

The homing pigeon has remarkable sense of direction. Pigeons can remember pathways that do not depend on visual signposts - for instance, getting to their ‘home’ rooftop even when landmarks are pulled down. They can do it when the sun shines from different directions at different times of the day or when it is overcast and the sun cannot be seen.

 

Dr Cordula Mora and her team in Aukland, New Zealand found that pigeons actually sense magnetic fields through iron-rich materials found in their beaks. The birds were placed in a cylinder with a food tray at both ends and an electric coil to create a magnetic field. The birds were rewarded if they followed the field and moved the correct way by placing food on the correct tray. The birds were found to learn very fast, which means they could clearly sense the magnetic field, as if it were a colour or sound of a particular pitch.

 

But if small magnets were taped to their beaks, or if the beaks were anaesthetized, the birds did not react to changing the direction of the field. This showed that it was in the beak that the birds had their magnetic field sensing equipment.

 

Sensitive to light

 

There is also evidence that with many birds, the sensors of magnetic fields is located in the eyes and depends on certain shades of light being present. This suggests a different mechanism – one where light of specific energies sets off a chemical process which depends on the orientation of the magnetic field. If this process is perceptible to the bird, it could adjust its direction of flight according to the magnetic field! A paper in Nature, published in July 2008, reports the identification of such a mechanism.

 

 A simple chemical arrangement that is sensitive to magnetic fields is a pair of electrically charged groups of atoms. Molecules are generally formed by atoms or groups of atoms which mutually borrow and lend charged particles, to get both groups into a more stable condition – a kind of co-operative co-existence. But the partners also get separated sometimes, and they float in their ‘more stable’ state, but with a net charge so long as they are separate. Such free-floating charged segments of groups of atoms are called radicals and a pair of them would be a radical pair.

 

Pairs of radicals are then lightweight but important players in chemical reactions and they have strong magnetic properties. Because they are magnetic, a magnetic field could orient them to react in one way when the field is strong and another way when the field is weak. The radicals would then go for one chemical reaction in one kind of magnetic field and for another reaction when the field is different. If the different reactions could affect the light sensitivity of the eye, differences in magnetic fields may be perceived in some visual manner!

 

 

[the writer can be contacted at simplescience@gmail.com]

Eco-travel

Mangalajodi - Community, Conservation and Culture - Dr.Pankaj Sharma

Mangalajodi - Showcasing Community, Conservation and Culture through Eco Tourism

-Dr. Pankaj Sharma

Mangalajodi –a village on the banks of Northern Chilika, is known for its tireless efforts in conserving birds which come to visit Chilika every year.  Mangalajodi was famous as ‘Poachers Village’ because of the involvement of villagers in Bird Poaching and selling it in the local market.  It was going on massive scale till Wild Orissa- a Bhubaneswar based NGO started working in the area and constituted the community into Bird Protection Groups. Transition was not easy; but continuous efforts through awareness and support from different agencies proved effective.  Community members made a formal organization called Sri Sri Mahavir Pakshi Surakshya Samiti (Bird Protection Committee) on 10 Dec 2000 and took a pledge not to kill the birds as well as not allowing anyone to do so. Committee members started conservation activities by regular patrolling in Mangalajodi Wetland. Annual Census started registering more number of birds each year.

Transformation from poachers to conservationist was not easy but more difficult was the rehabilitation and restoration of livelihood for those who have no skills other means of living than killing birds. Mangalajodi Ecotourism is a community led Eco-Tourism initiatives started with a goal to provide livelihood support to local community involved in conservation of Mangalajodi Wetland. Project is implemented by CPSW- an Orissa based NGO which is handholding the community to manage the facilities and improve the services for visitors. Earlier different methods were employed by the villagers in killing birds which also made them aware of feeding habits, distribution and migration pattern of birds. Their knowledge is now employed in making them Ecoguides, who give visitors an authentic experience of learning about Birds.  Mangalajodi hosts over 400000 birds of 200 different species during the peak season of which at least 80 are migratory birds.

 

What Mangalajodi offers to (Eco) Tourists?

·                    Birding from the Watch Towers: Mangalajodi is nearest place from Bhubaneswar to see birds in Chilika. It is also the place offering Birding from closest distance possible;

·                    Guided Boat ride on special routes to spot birds: Knowledge of Birds, their migratory patterns and breeding cycles from poachers-turned-ecoguides.

·                    Taste local cuisines which are prepared and offered on boat;

·                    Hear the story “Poachers to Protectors” from the locals;

 

 

How to reach Mangalajodi

Mangalajodi is approx. 75 Kms from Bhubaneswar en route to Chennai on NH-5. Bhubaneswar is well connected by air and train. Nearest Bus stand is Chandpur Tangi. Nearest Railway stations are Kalupada Ghat and Mukateswar.

 

Interested in visiting Mangalajodi (Chilika), please write to us at: dmecotourism@gmail.com or Call: + 91- 9238398849

 

Photo credits

Group of Godwits at Mangalajodi by Aditya Panda

Hand driven boat at Mangalajodi by Ghani Zaman

 

           

 

Web Page

Link of the Month

Mr Sharad Apte, an ornithologist, has recorded bird calls of birds in the Western Ghats with sophisticated equipments. He has spent 20 years of leisure time and resources studying birds and bird songs and has spent almost 10 years recording them .

Bird’s song and call are roughly classified; by their purpose; such as breeding songs and calls, alarm call, rising and retiring call as well as calls for communications etc. These are accompanied by colorful photographs of each bird enabling viewers to listen to bird songs along with the pictures. You will also enjoy the expert comments on seasonal behavior of the birds and the purpose behind each call.

Visit the following link for more information about his work

http://www.birdcalls.info/

 




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