Spheniscus magellanicus
Magellanic penguin

Magellanic penguins live and breed in the Neotropical region along the southern coast of South America. They are found from about 30°south in Chile to 40° north in Argentina, and the Falkland Islands. Some populations on the Atlantic coast migrate north up to the Tropic of Capricorn. ("Species factsheet: Spheniscus magellanicus", 2011; "Spheniscus magellanicus", 2010; Boersma, 2009)

Magellanic penguins primarily inhabit temperate regions of South America, but during the non-breeding season may follow oceanic currents northward into more tropical latitudes. During the breeding season, Magellanic penguins nest on shoreline grassland habitats that provide adequate, shrubby vegetative cover, but are near the ocean so parents can easily forage. This species may also nest within burrows on cliff faces. When not breeding, Magellanic penguins live pelagic lifestyle and spend nearly all of their time off the southern coast of South America. Individuals typically travel anywhere from 100 to 1,000 km off shore. While at sea, this species has been recorded to dive to depths of up to 76.2 meters. ("Magellanic Penguin", 2011a; "Spheniscus magellanicus", 2010; Boersma, et al., 1990; Stokes and Boersma, 1991)

Magellanic penguins' weights vary with the season. They tend to weigh the most directly prior to molt (which begins in March) since they are preparing to fast for the following few weeks. Males have a mean weight of 4.7 kg and females weigh a mean of 4.0 kg. The mean flipper length for males and females is 15.6 cm and 14.8 cm, respectively. The average beak length is 5.8 cm for males and 5.4 cm for females. Males and females have webbed feet that are, on average, 12.2 cm and 11.5 cm long, respectively. Adults and juveniles both have black bills, black backs, and white fronts. Adults have a symmetrical white band that originates at each eye, arches back on the sides of their heads, and comes together above their necks. Adults also have two black bands underneath their neck; juveniles only have one band. Juveniles display a range of white to dark gray patches on their cheeks. Juveniles have two layers of down before they develop their adult plumage. (Boersma, 2009)

Magellanic penguins are a monogamous species that upholds their pair-bonds for many seasons. An unmated male attracts a mate first by calling, which is more accurately described as "braying" like a donkey. Once an interested female comes forward, the male will walk in a circle around her and eventually will rapidly pat her with his flippers. A breeding pair often performs mutual preening to uphold their pair-bond.

Male Magellanic penguins also fight each other for both nests and females. When males fight before females have laid eggs, the larger male typically wins. These winners are more likely to breed and thus have more chicks. The winners' nest sites tend to be more covered and protected from the elements as well. When fighting occurs after egg laying, the winner, regardless of size, is typically the owner of the nest that he is trying to protect. ("Magellanic Penguin", 2011a; Martella, 2001; Stokes and Boersma, 1998; Williams, 1995)

Magellanic penguins nest close to shore. They prefer to build their nests under a bush, but will also dig burrows into substrate if necessary. They choose areas where the substrate is composed of small particles such as silt and clay and low amounts of sand. Magellanic penguins breed in dense colonies where nests may be only 123 to 253 cm apart. Adults will arrive at their breeding grounds in early September and lay two eggs in late October. The average annual reproductive success is 0.52 chicks per nest. The clutch hatches asymmetrically, and the first hatched generally is bigger and better able to obtain food from the parents. Thus, one chick typically dies from starvation unless there is an overabundance of food or the colony size is small. Eggs weigh 124.8 grams and are 7.5 cm long. The incubation period lasts for 40 to 42 days and the chick brooding period lasts from 24 to 29 days. The young fledge at 40 to 70 days old, typically during January to the beginning of March. Fledglings group together in creches and immediately take to the water, while adults remain on shore for several weeks to molt. Juvenile Magellanic penguins do not reproduce until 4 years of age. (Boersma, 2009; Borboroglu, et al., 2002; Reid and Boersma, 1990; Stokes and Boersma, 1998; Yorio and Boersma, 1994)

Both male and female penguins defend their nest, eggs, and young. Once the clutch is laid, incubation duties are shared and initially each parent will perform a two-week long shift. Parents switch more frequently as the incubation period progresses. When the young hatch after 40 to 42 days, they are semi-altricial meaning they are downy, immobile, and completely dependent on their parents for food and temperature regulation. Parents continue to alternate incubating and foraging duties, and the young are fed through regurgitation. The young are constantly cared for and brooded for 24 to 29 days, after which the parents spend extended periods of time foraging and will return to the nest every 1 to 3 days. At 40 to 70 days old, the young fledge and immediately take to the water in large groups, or creches. Fledgling penguins do not receive further parental care, as the parents remain on shore to molt. Once the adults have fledged, mixed groups of juvenile and adult penguins migrate north to the wintering grounds. (Martella, 2001; Williams, 1995; Yorio and Boersma, 1994)

Magellanic penguins live for an average of 25 to 30 years in the wild. Juvenile penguins suffer the highest mortality rate during their first pelagic migration, but annual survival slowly increases as they age. Causes of mortality for both juveniles and adults include predation, climatic variation, discarded human garbage, oil spills, and commercial fishing. (Boersma and Stokes, 1995; "Magellanic Penguin", 2011b)

Like most penguins, Magellanic penguins are primarily pelagic and are specialized for foraging in the open ocean. Magellanic penguins are migratory birds that travel south to breed on the southern shores of South America and nearby oceanic islands. During the breeding season they are significantly more terrestrial, as they nest and care for their young on sandy shores or cliff faces. At the end of the breeding season, adults and juveniles migrate north and take on a pelagic lifestyle, capable of foraging up to 1,000 km off shore.

Although both male and female Magellanic penguins are known to fight in defense of their nests, most fights involve two males who fight in territorial disputes. These fights are common on the breeding grounds, where colonies of up to 200,000 individuals are densely crowded and pairs may nest within 200 cm of each other. When they are ready to leave the nest, fledgling penguins immediately take to the ocean in large groups or creches. Adults will later join them at sea, and all will travel northward together in cold ocean currents.

Magellanic penguins display behavioral adaptations to cope with warm weather. If they get too hot, they can extend their flippers upward in order to increase the amount of surface area exposed to a breeze. (Borboroglu, et al., 2002; Walker, et al., 2005; "Magellanic Penguin", 2011b; Williams, 1995)

Specific territory size is currently unknown for Magellanic penguins. Individuals do not defend a feeding territory in the open ocean, but both males and female vigorously defend the immediate area surrounding their nests. The defended area fluctuates in size depending on nesting densities, but may be as small as 3 square meters. (Borboroglu, et al., 2002)

Magellanic penguins perform a variety of vocalizations and are able to discriminate between conspecific calls. Such calls include ecstatic display calls, mutual display calls, fight calls and contact calls. Males perform ecstatic display calls in the beginning of breeding season to attract a mate and during altercations with other males. These calls are described as "braying" for their similarity to the calls of donkeys. Both males and females use a mutual display call when they meet at their nest in the beginning of the breeding season and when they switch duties during incubation. Females respond more strongly to their mates' calls than to other male calls. The females stand up, look around and sometimes call back. Chicks can also discriminate between their parents' mutual calls and the mutual calls of another set of parents.

Mated pairs also use tactile and visual displays to communicate with each other and strengthen their bond. To show interest in a female, the male will walk circles around a potential mate and then pat her rapidly with his flippers. A mated pair will remain together for many years, and often perform mutual preening to uphold their bond.

Studies have suggested that penguins, in general, rely heavily upon their sense of sight to obtain food and navigate underwater. It has been suggested that these birds can see at least a portion of the ultraviolet spectrum. Study of the retina has also revealed that it lacks the ability to perceive the color red, and that they are very adept at perceiving blue or green spectra. This likely is connected to the fact that in the deep ocean, there is an abundance of blue and green coloration while red is rather rare. It has also been suggested that penguins' eyes are specially adapted to aquatic environments, as they share similar sensitivities with the eyes of fish.

Like most birds, Magellanic penguins perceive their environments through visual, tactile, auditory and chemical stimuli. (Clark, et al., 2006; Martin, 1985)

Magellanic penguins are piscivores. While their basic diet consists mainly of pelagic fish, their particular choice of prey varies on where they reside. Penguins that inhabit northern colonies, such as San Lorenzo, Punca Clara, Punta Loberia, feed primarily on anchovies. In the southern colonies of Monte Leon and Punta Dungeness, penguins prey on squid (Loligo and Illex species), sprats and hagfish. They can dive more than 76.2 meters while hunting. ("Magellanic Penguin", 2011a; Laurenti and Gallelli, 1999)

Penguin eggs and young chicks are prime targets for kelp gulls, lesser grisons and large hairy armadillos. While on land, red foxes, gray foxes, pampas cats and pumas prey on older penguin chicks, juveniles, and adults. Sea dwelling predators, including giant petrels, South American sea lions and orcas, feed on fledglings, juveniles, and adults. (Boersma, 2009)

At all life stages, Magellenic penguins are a valuable food source for various terrestrial and aquatic animals. As predators themselves, Magellanic penguins keep local populations of small fish and squid balanced. ("Magellanic Penguin", 2011b)

During their breeding season, magellanic penguins are popular tourist attractions. Over 100,000 people visit their nesting grounds at Punta Tombo each year. For a few years after 1982, this species became the target of human exploitation for their meat and skins, which were used to make gloves. ("Magellanic Penguin", 2011a; Boresma, 2008; Müller-Schwarze, 1984; Walker, et al., 2005)

There are no known adverse effects of Spheniscus magellanicus on humans. ("Spheniscus magellanicus", 2010; "Magellanic Penguin", 2011b)

When last assessed in 2010, the IUCN Red List categorized Magellanic penguins as near threatened. While an overall moderately rapid decrease is apparent, some smaller colonies of penguins have grown. During their annual migrations, penguins would often drift into shipping lanes and get oiled. However, changes to the Chubut provisional law moved the designated lanes to reduce oiling incidents. Magellanic penguins are also unintentionally caught in fishing nets and die as a result. Through commercial fishing humans are depleting populations of small fish which are a main component of Magellanic penguins' diets. The IUCN has proposed reducing by-catch of an anchovy fishery in Argentina and monitoring the effects on a penguin population in Punta Tombo as a possible solution. ("Magellanic Penguin", 2011a)