Page 159 - The Origin of Birds and Flight

Harun Yahya (Adnan Oktar) 157

for any physical, technological or biological process to take place.
Migratory birds must store sufficient fat in their bodies to be able to under-
take their long journeys. But since birds must also be as light as possible,
they need to be free of all unnecessary weight. Thus there is an exquisite
equilibrium in their fuel consumption, and in their flight speeds. If a bird flies
more slowly, it will consume more energy to propel itself. If it moves too
quickly, it will again expend more energy in order to overcome air resist-
ance. Therefore, the bird can fly economically only when it attains the most
appropriate speed for the least fuel consumption. Depending on the aero-
dynamic structure of its own body and wings, every species has its own op-
timal flight speed. For example, this is 45 kilometers (27.961 miles) per hour
in an Aztec dove, and 41.6 km/h (25.849 mph) for a parakeet. Birds con-
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stantly maintain these optimal flight speeds to permit energy savings, but
how they do so is still a mystery to ornithologists.
The fuel consumption of an American golden plover (Pluvialis dominica
fulva), for example, requires a very delicate calculation. Plovers migrate
from Alaska to Hawaii for the winter, flying non-stop over the ocean be-
cause there are no islands en route and unlike seabirds, they cannot rest on
the water. They manage their 4,000-kilometer (2,485-mile) journey in 88
hours, beating their wings continuously 250,000 times. They use up 70
grams (0.154 pound) of their 200-gram (0.440 pound) body weight as fuel.
To obtain the necessary propulsive force and heat to be able to fly, this
bird consumes an estimated 0.6% of its body weight every hour. This
means that after 72 hours—81% of the duration of its journey, this bird will
have consumed 70 grams (0.154 of a pound) of fat as fuel, which should
send it falling into the sea 800 kilometers (497.096 miles) short of its desti-
nation. Yet plovers never face such a danger, because they fly in a V-
shaped formation, thus enjoying a 23% energy saving. After 88 hours, they
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have 6.8 grams (0.0149 of a pound) of fat left. However, this remaining fat
is not a surplus, but is kept as a reserve in case of emergency, such as
when the wind blows from the wrong direction. And so, these birds under-
take an exceptionally long journey with the minimum of fuel.
Professor Werner Gitt, director of the German Federal Physics and
Technology Institute, expresses his admiration for this economical energy
consumption :
The extremely low specific rate of fuel consumption, p=0.6% of its
weight per hour, is all the more amazing when we compare it that of
manmade aircraft which is many orders of magnitude greater (for a hel-
icopter p=4 to 5%; and p= 12% for a jet plane). 3