For breeding, the emperor penguinsuse certain criteria to choose a spot: it must be solid ice year long, and norisk of ice becoming too soft.
At the end of Antarctic summer, the breeding ground is not farfrom the open water where the penguins can feed, but by the end of winter, thebreeding ground is very far away from the nearest open water. To get access forfood, all the penguins of breeding age must travel this great distance.Behavior and adaptation of emperorpenguins:Tosurvive in a very low temperature, the emperor penguins have large stores ofinsulating body fat and several layers of scale-like feathers that protect themfrom icy winds. They also huddle close together in large groups to keepthemselves, and each other, warm.Comparedto other bird species, the emperor penguin breeds in the coldest environment. Water temperature is a frigid which is muchlower than the emperor penguin’s average body temperature of 39 °C(102 °F). The species has adapted in several ways to counteract heatloss.
Feathers provide majority of insulation, and it has a layer of skin fatwhich is thick enough before breeding. (Williams, Tony D. 1995). This gives the fatty skin layer whichhinders their movement. Another penguin, the Magellanic penguins has less insulation fat (Hogan C.M. 2008).
A bird’s down feather isthe numbers of which form an insulating layer under the contour feathers. Thereason that the densityof contour feathers is approximately 9 per square centimeter is because it is acombination of dense afterfeathers and down feathers. This high density is crucial for insulation (Khan, A., 2015). The feathers are held erect on land by muscles andthus decreases heat loss by trapping a layer of air next to the skin. On theother hand, the feathers are flattened in water, thus waterproofing the skinand the downy under-layer. (Williams,Tony D.
1995). Kooyman et al. described that the feathers aremaintained oily and water-repellent, and thereby insulation, that is importantfor preening. (Kooyman GL et al, 1976).At a threshold of body mass, a metabolic and endocrineshift, possibly related to a limited availability of fat stores, acts as a”refeeding signal” that improves the survival of penguins to fasting (Robin etal., 1998).Thermoregulation in emperorpenguins:Without changing its metabolism, the emperor penguin canmaintain its core body temperature that extends from ?10 to 20 °C (14 to68 °F). (Williams, Tony D.
1995). Below this temperature range, its metabolic rateincreases significantly, although an individual can maintain its core temperature from 38.0 °C (100.4 °F) down to ?47 °C (?53 °F). Emperor penguin increasesits metabolism by Movement by breakdown of fats by enzymes, induced by ahormone glucagon, swimming, walking, andshivering. At temperatures above 20 °C(68 °F), an emperor penguin usually gets agitated as its body temperatureand metabolic rate rise to increase heat loss. Raising its wings and exposingthe undersides increases the exposure of its body surface to the air by 16%, facilitatingfurther heat loss. Abioticvariables with data loggers glued to the feathers of eight individually markedemperor penguins were performed by investigators to research theirthermoregulatory behavior and to estimate their “huddling timebudget” throughout the breeding season (pairing and incubation period).
Contrary to the classic view, huddling episodes were discontinuous and of shortand variable duration. Despite heterogeneous huddling groups, birds had equalaccess to the warmth of the huddles. Throughout the breeding season, theambient temperature is raised. Due to the tight huddles, ambient temperatureswere above 20 degrees C of their huddling time. This complex social behaviorenables all breeders to get a regular and equal access to an environment whichallows them to save energy and successfully incubate their eggs during theAntarctic winter. (Gilbert C et al, 2006).
Walking200 km (from the sea to the rookery and back) requires less than 15% of theenergy reserves of a breeding male emperor penguin initially weighing 35 kg.The high energy requirement for thermoregulation (about 85%) would, in theabsence of huddling, probably exceed the total energy reserves. (PinshowB, et al,1976).Le Maho et al, found that the metabolic rate during treadmill walking increasedlinearly with increasing speed (Le Maho, 1976).
As mentioned before, thereare about seventeen or eighteen penguin species in the world, in this review, someof the penguins are compared with emperor penguins. The king penguins are about 32 inches tall, but shorter than emperorpenguin. They breed at the northern Antarctica, and the FalklandIslands. Compared withother birds, the energetic cost of feather synthesis is the lowest in king penguins andconsequently the energetic efficiency is the highest (Cherel Y, et al. 1994).
The Macaroni penguin (Eudypteschrysolophus) is a species of penguin that are found in the Sub Antarctic to the Antarctic Peninsula. One of six species of crested penguin, it is very closely related to the royal penguin, and some authorities consider the two to be asingle species. It bears a distinctive yellow crest, and the face andupperparts are black and sharply delineated from the white underparts.
Like allpenguins, it is flightless, with a streamlined body and wings stiffened andflattened into flippers for a marine lifestyle.The only residence of the Adéliepenguin (Pygoscelis adeliae) is along the entire Antarctic coast, They are among the most southerly distributed of all seabirds, along with the emperorpenguin, the southpole, Wilson’s storm petrel, the snowpetrel, and the Antarcticpetrel. They are namedafter AdélieLand, in turn named for Adèle Dumont D’Urville, the wife of French explorer Jules Dumont d’Urville, who discovered these penguins in 1840. Adélie penguins usually swim at slightly lower speedthan emperor penguins (Sato, K.
et al, 2010).