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Sunday, October 11, 2009

Bird migration: why do they do it?




An interesting new article concerning why birds migrate has been posted on the internet. Here is a part of the article:

Written by 



"Bird migration looks like a bad idea at first glance — all that energy needed to fly thousands of kilometres, all those predators along the way and the promise of doing it all over again just a few months later."
"But of course Mother Nature knows exactly what she is doing. If you've ever wondered, as we did, what all that back and forth across the sky is about, read on."


Why migrate in the first place?
"Two words: food and babies. It turns out the longer days of the northern hemisphere's summer mean a bumper crop of yummy bugs, which in turn means more baby birds."
"Even though migration is quite an investment and quite risky, the payoff can be pretty huge," says biologist Jody Allair of Bird Studies Canada, a non-profit conservation group.
"If you've spent any time up in a bog in Algonquin Park in early June, you'll know why. The food abundance is just out of control."
"But the good times don't last forever. Starting in late summer, the bug banquet tapers off, and within weeks there's a chill in the air signaling the killing cold to come. Time to head south."


To read the remainder of this article please click on the following link:
http://www.cbc.ca/technology/story/2009/09/16/f-birds-migration.html

From research I have done I discovered that Bird Studies Canada has a website where you can get involved in reporting 
bird migration you see to experts. This can be done at the website:
http://www.bsc-eoc.org/volunteer/cmmn/index.jsp?lang=EN&targetpg=index

From the website:


"Watching birds is more popular than ever, and thousands of Canadian citizens are contributing their bird observation skills to science by participating in Bird Studies Canada's bird population surveys.  These "Citizen Scientists" provide a tremendous service to all Canadians by volunteering their time to track the health of bird populations." 
"Not only are birds important in their own right, they also serve as early warning systems for problems in the environment we all share.  Peregrine Falcons signaled the cumulative effects of DDT, American Crows and Blue Jays reflect the spread of West Nile Virus, and many bird species are responding to perhaps the greatest challenge facing us now, global climate change."



Bird Studies Canada has a number of options for people who want to volunteer to report what they have seen while engaging in bird watching. Please click on this link to see the types of volunteer options available to you:
http://www.bsc-eoc.org/volunteer/index.jsp?lang=EN&targetpg=progchoose

"Many birds that breed in North America migrate to areas south of the Tropic of Cancer (southern Mexico, Central and South America and the Lesser and Greater Antilles in the Caribbean Sea) in the fall (August-October) because of a decrease in their food supply. Many of these birds are insectivores; they eat mainly insects. (Most insects do not survive the North American winters except in larval or egg forms.) These birds remain on their non-breeding (wintering) grounds until April. Then in spring they migrate back to their breeding grounds in North America to take advantage of the plentiful insect food supply to breed and raise young."

"These birds that migrate south of the Tropic of Cancer are called Neotropical migrants. A more correct term now used is Nearctic migrants. Nearctic is a word that refers to the Arctic as well as the temperate parts of North America. Since these birds spend more time in the tropics than on their North American breeding grounds, they would be migrating into the Nearctic region. Thus, they would be Nearctic migrants. They actually may be tropical birds that have learned to fly north to exploit the plentiful insect food resources there."

"To prepare for migration, birds become hyperphagic. That means they eat more food, which is stored as fat for their long journey. Fat is normally 3% to 5% of the bird's mass. Some migrants almost double their body weights by storing fat before migration. The ruby-throated hummingbird weighs only 4.8 grams and can use stored fat to fuel a non-stop, 24-hour flight across a 600-mile stretch of open water from the U.S. Gulf coast to the Yucatan Peninsula of Mexico!"

How far do birds migrate?




"It depends on the bird species."
"The arctic tern may hold the record for longest migration distance since it flies about 30,000 km (18,600 miles) each year traveling between its arctic breeding ground and non-breeding area in the Antarctic. This amazing feat is possible because terns eat fish and can feed during their long journey."
"Most songbirds don't fly to their non-breeding grounds non-stop. They stop a number of times to rest and feed during migration. The places they stop are called stopover sites, or staging areas. Birds remain at stopover sites for varying amounts of time based on the weather and how much fat they have stored. Some birds stop only one day to rest and feed, and then continue their migration. Others will remain at stopover areas for weeks. Most Neotropical migrants stop
along the way to rest and feed."


"Some birds are short-distance migrants and migrate only as far as they need to find food such as insects, seeds and berries."
"Some birds are austral (southern) migrants. In the tropics, they migrate north to breed, then head south at the end of the breeding season. In Belize, they also are called dry-season residents because they migrate north to breed during Belize's dry season."

How high do birds fly when they migrate?



"Some geese and ducks fly at incredible heights. Bar-headed geese have been recorded as high as 29,000 feet when they migrate over the Himalayas! That's five miles above our heads, even higher than Mount Everest!"
"Most night-migrating songbirds fly below 2000 feet (600 m) when flying over land. Some will fly as high as 6,500 feet (1,980 m). Occasionally, they may fly higher to reach favorable winds."
"The wind sometimes causes birds to fly at certain heights. When the bird is flying into the wind (called a headwind), it flies very low. When the wind is blowing the same direction as the bird, pushing it along (called a tailwind), it will fly high, where the wind is the fastest."
 How do birds navigate?


Birds have excellent vision and rely on visual landmarks for local and long-distance migration. They use key land features such as mountains, rivers, coasts or even large buildings.
There are three types of "compasses" a bird uses to find its way. Birds can use the sun, the stars and the Earth's magnetic field.
  1. Birds use the sun as a compass. They use the positions of the sun during the day to navigate. They also can use the setting sun as an indication of due west.

  2. Night flyers use celestial navigation, which means they find their way by knowing the patterns of the stars in the sky, and by knowing special stars like the North Star. In their first year of life, birds memorize the position of the constellations in relation to the North Star. These star patterns stay the same even though the Earth moves through space, making the constellations appear to move to different spots in the sky during the year.

  3. Birds have tiny grains of a mineral called magnetite just above their nostrils. This mineral may help them to navigate using the Earth's magnetic field, which tells the bird what direction is true north.
Petrels and pigeons can use their sense of smell to find their way, but it is used only in addition to the sun, stars and magnetic field.




 Source of image:http://www.vaneedenupick.com/birdwatching.html

Here is are two links to videos about bird migration:


http://open-video.org/details.php?videoid=6130  (click on the format of video you wish to view the video in)


http://www.science.gc.ca/default.asp?Lang=En&n=75365FD3-1

or  http://www.science.gc.ca/videos/ET_2/et2_4_LAN_e.rm  (to view this video you need to use Real Player)

Here are some other websites which discuss bird migration:

http://www.naturia.per.sg/buloh/birds/migration.htm

http://www.paulnoll.com/Oregon/Birds/Avian-migration.html

http://www.wbur.org/news/npr/113663006

A Discussion of North American Migration pathways:  http://www.birdnature.com/flyways.html

A map showing Migration pathways birds take to the Arctic: http://maps.grida.no/go/graphic/major-global-bird-migration-routes-to-the-arctic



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Thoughts worth thinking about

"Our subconscious minds have no sense of humor, play no jokes and cannot tell the difference between reality and an imagined thought or image. What we continually think about eventually will manifest in our lives."-Sidney Madwed



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A person's true wealth is the good he or she does in the world. - Mohammed



Our task must be to free ourselves... by widening our circle of compassion to embrace all living creatures and the whole of nature and its beauty. -Albert Einstein



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The unselfish effort to bring cheer to others will be the beginning of a happier life for ourselves. - Helen Keller



Aim for success, not perfection. Never give up your right to be wrong, because then you will lose the ability to learn new things and move forward with your life. Remember that fear always lurks behind perfectionism. Confronting your fears and allowing yourself the right to be human can, paradoxically, make yourself a happier and more productive person. - Dr. David M. Burns



Life is as dear to a mute creature as it is to man. Just as one wants happiness and fears pain, just as one wants to live and not die, so do other creatures. -His Holiness The Dalai Lama



Mankind's true moral test, its fundamental test (which lies deeply buried from view), consists of its attitude towards those who are at its mercy: animals. And in this respect mankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it. -



Milan Kundera, The Unbearable Lightness of Being



The worst sin towards our fellow creatures is not to hate them, but to be indifferent to them. That's the essence of inhumanity. -George Bernard Shaw

Ego's trick is to make us lose sight of our interdependence. That kind of ego-thought gives us a perfect justification to look out only for ourselves. But that is far from the truth. In reality we all depend on each other and we have to help each other. The husband has to help his wife, the wife has to help the husband, the mother has to help her children, and the children are supposed to help the parents too, whether they want to or not.-Gehlek Rinpoche Source: "The Best Buddhist Writing 2005 pg. 165

The hostile attitude of conquering nature ignores the basic interdependence of all things and events---that the world beyond the skin is actually an extension of our own bodies---and will end in destroying the very environment from which we emerge and upon which our whole life depends.