The Birdman Chronicles: The Penguin = AotW

This is the first entry in a new weekly feature for the blog. Now normally it would be a single species but this has fallen perfectly as today is penguin awareness day! So this week I'll be doing a little piece on the penguin.

The Penguin

Although all penguins share common features they are all uniquely different, they occupy different types of coast, different regions and climates, they also have different lifestyles and make use of different resources, this is what gives them their individuality in the ecosystem.

Penguins are a flightless group of birds, which belong to the family Spheniscidae. Across the world there are 17 species of penguin, all of which can be found in the southern hemisphere. In light of not being able to fly the penguin has evolved quite differently to a lot of other avian species, birds that fly need a skeleton which is as light as possible, whereas the penguin is much heavier and robust as a light skeleton is not advantageous, a light, hollow skeleton would mean the bird would need to use a considerable amount of energy to overcome their natural buoyancy, a denser skeleton gives them greater strength and reduced buoyancy.

The distribution of penguins in the Southern hemisphere

The penguins history is thought to lead back to 50 million years ago, giving them a relativity long evolutionary history, this explains some of their unique structural differences, such as flippers (instead of wings) and a modified breast bone. despite this, many of the penguins alive today are very similar, they mostly have blackish upperparts and whitish underparts on the abdomen and flippers, acting as camouflage against the lighter sky when viewed from below and vice versa. Another unique adaptation are its interlocking feathers which act as barrier to water, each feather contains small muscles which allows them to be held tightly down against the birds body whilst it swims, acting as a sort of water proof layer. Not only this but it also means that little air is trapped within the plumage helping to further reduce buoyancy. In contrast, when on land these feathers are erect to do the opposite by trapping warm air to provide sufficient insulation. Fat deposits under the skin also provides insulation; a highly adapted vascular system is also present to maximize this. It works in such a way that heat loss can be greatly reduced from the extremities (flippers and feet) by keeping them as low as 6 Celsius despite a core body temperature of 39 Celsius, this reduces heat loss during winter and vice versa in summer months through a reversal of the system.

Penguins must retain their waterproof coating in their plumage, to do this they annually push out the old feathers and grow new ones during a molt. This requires a period of fasting by the penguin as they cannot reenter the water until their plumage has fully returned, and the water is where their entire food source is located. Incubation and brooding are also periods of fasting for penguins. During these phases they can greatly reduce their metabolic rate in order to reduce the rate at which fat reserves are used. To ensure the feathers keep their waterproofing, feathers are preened constantly with a waxy substance from a gland at the base of the tail. In areas that are inaccessible for self preening allopreening within the flock is seen, this is also part of their pair bonding behaviours. However, this is not seen in all penguin species

Whilst ungainly on land the penguin is a perfect aquatic predator in the water, they can reach speeds of up to 14km per hour for prolonged periods of time. They dive in search of prey and when located, they chase it and swallow it whole under the water, they have good all round vision and are able to alter the lens in their eye depending on if they are on land or in water, enaing they can compensate for the differing refractive indexes. The penguins eye is also more sensitive to greens and blues (due to hunting in the water). They eat fish, cephalopods and crustaceans as well as the occasional small stone to help break up food in the stomach. All penguins have the ability to dive to around 100m but larger species such as the king and emperor penguins have been recorded at around 500m. Healthy adult penguins have few natural predators on land, although on occasion Sea Lions have been known to take them on land. On land it is the eggs and chicks that are more at risk, Skuas and Gulls will often predate them, whereas in the water adults are prey to leopard seals, sea lions and orca.

As a last note I will say that penguins are declining on a global scale. the main suspects are climate change, fisheries and disease and pollution. A greater understanding is needed of these great birds, in terms of their ecology and how they are affected by such threats. That is where days like today are great, in raising the awareness needed to help support the penguin.

(Information from a variety of sources including the International Penguin Conservation Work Group (IPCWG) go check out their website and their specific work in protecting this marvelous bird)

http://www.penguins.cl/index.htm