C. Michael Hogan PhD
November 27, 2008
This flightless bird is a medium sized penguin found in temperate marine environments, breeding chiefly in coastal areas of Patagonian Chile and Argentina. This penguin is the most abundant and southernmost distributed of the Spheniscids, although it is not nearly as cold-tolerant as its southern neighbor species: Gentoo, Emperor and Chinstrap.
DISTRIBUTION AND HABITAT
The northernmost Atlantic colonies are at the Valdes Peninsula and a small rookery immediately south of Punta Ninfas, where about 50 breeding pairs are found. One of the largest colonies, numbering 450,000 to 600,000 breeding pairs, is located at Punta Tombo, Argentina. At about one degree latitude further south there are colonies on Isla de Tora and Isla de Torita. Then at about ten degrees latitude further south there is a rookery at Isla de los Estados. They breed as far south as Cape Horn, the location where the first European, Ferdinand Magellan, sighted the species in 1519. Winter migration along the Atlantic coast reaches southern Brazil. Along the Pacific Ocean coast breeding occurs as far north as Concepción, Chile and winter migration extends to central Chile, overlapping the Humboldt Penguin range. Accidental occurrences have been noted in New Zealand.
Adults have a body mass of approximately five kilograms with overall length of about 70 cm. The wings are elongated, exhibiting a fused wrist joint that denies flexing, but provides a rigid form enhancing swimming strength, that is also abetted by the species webbed feet. (Lynch) The wedge-shaped tails is abbreviated in length. The majority of S. magellanicus sport a white band on each side of the cranium, along with an additional white band, starting below the throat, and extending along the flank; plumage consists of very stiff feathers. There is a yellow cross-stripe on the bill. Similar to other penguin species, Magellans manifests counter shading, a black dorsal contrasted with a silver-white ventrum.. Such colouration provides camouflage for its predatory ways, but also a defencive element to deceive its enemies. Chicks and juveniles have grey-blue plumage; they also exhibit white blotches on their feet, which colouration persists until about age nine.
Sexual maturity for both genders occurs at approximately age three. The breeding season is bifurcate, with an initial period in September/October (Müller-Schwarze) and a second period at the beginning of the calendar year (Todd). Combat may occur over nesting sites, particularly between males. Magellanic Penguin couples click the tips of their bills together in a courtship ritual Both sexes contribute to the construction of one to three meter deep burrows in near coastal locations, where they can find soft soils, which also manifest structural integrity. The female typically lays two off-white eggs within the burrow, with an average mass of about 130 grams. Hatching usually occurs within six weeks, with both parents participating in incubation as well as parenting in their first four weeks of life. Fledging occurs two to four months after hatching.
I observed the Magellanic Penguin to achieve a respectable running velocity compared to some of its cold weather cousins, such as the Emporer Penguin, whose speed and mobility are impaired by a thick blubber layer. S. magellanicus also is able to climb rocky bluffs with ease, but this endothermic bird is correspondingly intolerant of very cold weather, due to its lack of dermal insulation. After moulting on land and fledging of the chicks, colony members marshal on the beaches preparing to re-enter their marine hunting waters.
A chief predator is the Patagonian Fox, but I also observed the Great Skua to be a constant harassing threat to eggs and chicks, especially when nesting sites are chosen on exposed cliffs rather than subterranean burrows S. magellanicus is most at home in the marine waters as an adept swimmer and diver. There it hunts primarily fishes, and can consume a herring or other prey whole. Nest materials are typically tussock grasses gathered from the coastal plain, which are abundant for example in locations such as Seno Otway. The coastal plain at the Otway colony is characteristic of an ideal situation for Magellanic Penguin breeding; the rolling dunes are stabilized by tussock clump grasses that offer wind protection and hold the soil together for good burrow construction.
S. magellanicus can interbreed with other genus members, most notably observed being hybrids with the Humboldt Penguin. Penguins are very social animals, with several breeding pairs sometimes sharing a common burrow. In mild wind periods it is common to see Magellanic Penguins standing at the edge of a burrow and conducting mutual preening, especially with a breeding pair.
Oil spills or other chemical marine upsets remain the greatest episodic threat to this penguin, due to the concentration of birds within a dense colony setting. Oil in the marine evironment poses a risk by subjecting the skin to coating and interfering with thermo-regulatory functions. A 1991 oil spill in near Punta Tombo affected 17,000 penguins with various degrees of outcome from death to severe weight loss. (Fiedler) Exposure to petroleum also radically alters hormonal balance; for example the oil affected females had severely diminished levels of luteinizing protein, testosterone and plasma estradiol. These alterations explain the reduction in fertility observed; moreover, in oil-exposed females elevated levels of corticosterone are found, an indicator of increased stress. Interestingly this stress indicator is further elevated, if oil is washed from the plumage, indicating that the conventional strategy of cleaning birds is not necessarily a fruitful solution.
The species is particularly vulnerable to tanker oil spills, since its breeding colonies are concentrated along major petroleum shipping lanes. Progress has been made in coastal species protection through implementation of the Patagonian Coastal Zone Management Plan.(Conway) For example a Japanese company had proposed to kill 48,000 Magellanic Penguins per annum to make golf gloves, but that effort was defeated.
* R.N. Gibson, R.J.A Atkinson and J.D.M. Gordon (2007) Oceanography and Marine Biology, CRC Press, 560 pages ISBN 1420050931
* Wayne Lynch (1997) Penguins of the World, Firefly Books, 143 pages ISBN 1552091805
* Dietland Müller-Schwarze (1984) The Behavior of Penguins: Adapted to Ice and Tropics, SUNY Press, 193 pages ISBN 0873958667
* Frank Todd (1981) Sea World of Penguins, Harcourt, New York
* William Conway (2005) Act III in Patagonia: People and Wildlife, Island Press, 344 pages ISBN 1559635185
* Peggy Lee Fiedler and Peter M. Kareiva (1998) Conservation Biology: For the Coming Decade,
Published by Springer, 533 pages ISBN 0412096617