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The Sociable Nest
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Written by Candice Swarts
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Monday, 01 December 2008 |
Life Cycle of a BirdPart 4: On the Wing
Being able to fly makes a bird so much more unique and intriging than any other animal... Their five-fingered limb has developed into a more suitable structure, ultimately making them airbourne. Each bird's wing is unique in shape and size. This gives them a wide range of different flying methods, manoeuvrability and speed. The heaviest flying bird is the Great Bustard weighing in at a maximum of 21 kg.
Searching for Food
The power of flight gives a bird huge advantages especially in the search of food. Birds can hawk insects out of the sky, hover over a flower to extract nectar or chase after their prey. Peregine Falcons are the fastest-moving birds when diving. It can reach speeds of up to 250km/h. Birds of prey make use of a soaring technique by means of thermals and updrafts. This saves energy and enables them to search for food for long periods. The Condor is the longest soaring land bird. Vultures have the slowest wingbeat at 1 beat/sec.
The Ruppell's Griffon Vulture can reach high altitudes of 11,300m (as a result colliding into aeroplanes). This makes them the highest flying birds. Once they find a carcass, they will gorge themselves so much that they can bearly fly. 
(Photo of a Griffon Vulture by Ben Bawden)
Hummingbirds, Kingfishers and Kestrels are well known for their ability of hovering. Hummingbirds have the fastest wingbeat at 90 beats/sec. The nectar from flowers are quick fuel sources for them.
(Photo of a Hummingbird by Gustavo Durán)
Migration Over half of the world's bird species carry out long range movements or migrations. This is to exploit the seasonal food changes and to breed where the supply is best. Birds migrate in flocks or singularly. The V-shaped formation is a common method for reducing energy spent during migrations.
(Photo of Canadian Geese by Denis Collette)
Migration is a dangerous and risky task. Millions of birds are blown off course, die of starvation or are attacked by birds of prey gathering along migration courses. Some birds will fly through the night to reduce the risk of being attacked. Up to three-quaters of the current years Barn Swallow young fail to reach their birth place.
 Light Blue: | Northern Wheatear | | Dark Blue: | Short-tailed Shearwater
| | Green: | Amur Falcon | Yellow:
| Ruff | Pink:
| Swaison's Hawk | Red:
| Arctic Tern |
Birds instinctively know when the time has arrived to set off.  In the weeks leading up to their departure, most migrants store extra body fat for fuel to power their flight. They become increasingly restless and some species form flocks that make several 'false starts' before their real journey begins.
(Photo of Snow Geese by Sonya)
However, the set off time may vary with weather conditions as seen more recently due to Global Warming. The longest two-way migration is the Arctic Tern at 40 200 km.
A lot of research has been done to determine how birds know their direction. These are the methods researchers believe birds use for navigation:
Compass: Birds have a natural compass as they have magnetite in their nostrils which enable them to sense the Earth's natural magnet (North).
Sight: Birds use familiar land marks to map their way home.
Smell: Birds use distinctive smells from the oceans, forests, beaches etc. to pin point their location.
Sun and Stars: This is another compass that a bird may use.
Endurance The Wandering Albatross has the greatest wingspan at up to 3,63m. This is followed close behind by the landbirds, Andean Condor and Marabou Stork, tied at a wingspan of 3,2m. Having a large wingspan helps with endurance. Although, the Sooty Tern can fly for 3 to 10 years without landing. The Common Swift has a record of 3 years without landing. Because legs are virtually non-existent in swifts, they live most of their life airbourne. The family scientific name comes from the Ancient Greek απους, apous, meaning "without feet", since swifts have very short legs and never settle voluntarily on the ground, perching instead on vertical surfaces. The tradition of depicting swifts without feet continued into the Middle Ages.
(Photo of Swifts by Andy Orenstein)
» 4 Comments
1Comment
at Thursday, 04 December 2008 08:42
each time I read about the migrations and the distances travelled it astounds me anew; it honestly is almost beyond comprehension! A great read, thank you, Candy!!!!
2Comment
at Thursday, 04 December 2008 12:32
Yeah a great read and a brilliant post - thank you Candyfloss!!
3Comment
at Thursday, 04 December 2008 17:05
"the Sooty Tern can fly for 3 to 10 years without landing. The Common Swift has a record of 3 years without landing"
How do they sleep? I have to know! :-)
4Comment
at Monday, 08 December 2008 11:32
I've read that swifts mate and sleep in the air. The sooty tern also sleeps in the air but I'm not sure if they mate in the air as well.
Sooty Terns do not sleep on the water as their feathers soak up to much water and as a result they sink. The terns sleep in short snatches on the wing.
Swifts stretch out their feathers so that they glide and are then able to sleep.
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The Sociable Nest 
