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et al. investigated the changes in the rate of body mass loss, body
composition, and plasma concentrations of uric acid and urea. In chicks, after
the first few days, a steady state was reached in the proportions of the energy
derived from proteins and lipids with proteins accounting for a constant 4%,
and the remaining 96% being from lipids. The same proportions were maintained
until body mass had decreased to 24 kg. Below this value the proportion of
energy derived from proteins increased progressively. Rate of body mass loss
and plasma uric acid and urea concentrations closely reflected the changes in
protein utilization: Emperor penguins fast during the spring, but for periods
of only 2-3 wk. They found a 2.5 times higher value for rate of body mass loss,
uric acid, and urea during spring, suggesting lower effectiveness in protein
sparing at that time. It may be attributed to the lower initial lipid reserves
of spring birds. (Robin, J. al, 1988).

Breeding patterns:

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Emperor penguins are monogamous (Williams, Tony D. 1995). In May and
June, during
each breeding season, female lays her egg and then she hands over to the male.
After that she travels to the sea to feed. Unlike other birds, no nest is built.
The egg is incubated on the feet of the parents. The eggs are hidden from harsh
weather and protected by feathered skin. This process is called, brood pouch. In the next 2 months, the male
emperor penguins must adjust and survive with the adverse weather condition,
without eating. Compared with other penguin species who are usually
aggressively territorial, emperor penguins huddle together for warmth. This
togetherness is unique for this species. They take turns moving towards the
inside of the pack, where it is warmer, thereby sustaining the entire group. Males just sit and wait and
protect their egg (later the chick) for over 120 days (average 115), during
this time they will lose about 40% of their body weight.  The females come back in July, bringing with them food in
their bellies which they regurgitate for the chicks to eat. When females
return, they relive the male from taking care of their babies/chick. The males
then travel to the ocean for their own food. After a few months, the
juveniles leave the shelter of their mother’s brood pouches (Williams,
Tony D. (1995). The Penguins. Oxford, England: Oxford University
Press. ISBN 0-19-854667-X. p 28) and the chicks huddle together in creches for warmth and
protection, whilst both parents head to the ocean to fish. In December, penguin
chicks become independent during the height of the summer food supply and thus
able to survive better.

Emperor penguins are adapted to travel using strong claws on
their feet to help grip the surface. If they find a good downslope, they also
slide on their sleek bellies. The emperors have developed unique voices,
recognizing each other. They produce distinctive tones that their breeding
pairs and even their offspring can identify. They stay in and around the
Antarctic ice their entire lives.

During the entire time
of breeding, they do not eat anything. Most male penguins will lose about
12 kg (26 pounds) while they wait for their chicks to hatch (Daddy Dearest, 2012). The
mean weight of males at the start of the breeding season is 38 kg
(84 lb.) and that of females is 29.5 kg (65 lb.). After the
breeding season, this drops to 23 kg (51 lb.) for both sexes (“Emperor Penguin, Aptenodytes
forsteri at Marine”. Retrieved 3 November 2008).  

The emperor penguins have no breeding territories. Both
members of a pair are not to be separated until the egg is laid and transferred
to the male. Both birds remain silent after mating and thereby reduce the risk
of having the pair bond broken by unpaired birds. A key energy saving technique
is Huddles. Ancel et al, studied the behavior of four pairs before laying.
Temperature and light intensity measurements allowed them to precisely detect
the occurrence of huddling episodes and to determine the surrounding
temperature. The four pairs huddled simultaneously for only 6 per cent of the
time when weather conditions were harshest. Despite this asynchrony, the
huddling behavior and the resulting benefits were similar between pairs. By
contrast, the huddling behavior of mates was synchronized for 84 per cent of
events. By coordinating their huddling behavior during courtship despite the
apparent confusion within a huddle and its ever-changing structure, both
individuals save energy while securing their partnership. The cold and
the long breeding fast continuously form and break up, but not all birds are
involved simultaneously. The male emperor penguins must huddle together
to keep themselves warm in windy wintry weather.
They take turn to go to center in the giant hurdles ( Ancel, A et al,  2009). In the hardship of travel, courtship, and
incubation in about 120 days, the males lose about half of their weight.  Hatching may take as long as two or three
days to complete, as the shell of the egg is thick. (Williams, Tony D.1995).
Newly hatched chicks are covered with only a thin layer. They are dependent
on their parents for food and warmth. If the chick hatches before the mother’s
return, the father feeds it a curd-like substance composed of mainly protein and lipid, which is produced by a gland in his esophagus. (Williams, Tony D. 1995). The young
chick is incubated in what is called the guard phase,
spending time balanced on its parent’s feet and sheltered in the brood pouch. (Burnie D and Wilson DE 2005).

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