Members of the extant genus, Spheniscus, are known as the banded penguins, because of the band of black coloration that runs around their bodies. The genus name literally means "wedge-shaped". The four extant species are similar in color pattern and are known as "jackass" penguins because they emit loud calls to locate each other that resemble the bray of a donkey (Stefoff, 2005).
A common coloration theme unites the extant species such as, distinct spots on their abdomens, a small vertical stripe upon their back and a small patch of lightly feathered or nude patch of skin around its eyes that has a pink or whitish coloration (Stefoff, 2005).
The genus Spheniscus, both extant and extinct, is not found anywhere along the Antarctic coasts. All but one of the extant species of Spheniscus inhabit temperate climates, which include South Africaand the southern coastal areas of Argentina and Chile. The Galápagos penguin (Spheniscus meniculus) is found on along the coasts of theGalapagos Islands and inhabits one of the most northern extents of the globe occupied by any penguin species (Stefoff, 2005).
All species of penguin within the genus Spheniscus raise their young in burrows (Stefoff, 2005).
The genus Spheniscus (banded penguins) is comprised today of four extant species: Magellanic penguin (Spheniscus magellanicus), Humboldt penguin (Spheniscus humboldti), Galápagos penguin (Spheniscus mendiculus) and the African penguin, black-footed or jackass penguin (Spheniscus demersus) (Stefoff, 2005).
The genus Spheniscus (banded penguins) also presently contains four known extinct species, which include three from the Late Miocene to the Early Pliocene (3.6 -11.6 Ma) of the central Andean coast (Spheniscus chilensis, Spheniscus megaramphus, Spheniscus urbinai) and the oldest known member of the genus is from the Middle to Late Miocene (11–13 Ma) of Cerro La Bruja, Peru (Spheniscus muizoni) (Gohlich, 2007; Ksepka & Clarke, 2010).
Spheniscus demursus is a fairly accurate representative for the genus, Spheniscus. Adults of the species stand around 45 cm tall and weigh an average of 3.1 kg (Cooper, 1977; Stefoff, 2005).
Researchers analyzed skeletal remains and estimated body mass for all fossil penguins. The study found that fossil species ranged from 3 kg to 81 kg in total mass. The largest fossil species of penguin was approximately 2.5 times as massive as the largest extant spheniscid. The findings show that members of Spheniscus are small-sized penguins in both extant and extinct forms (Livezey, 1989).
All extant members of the genus have coloration that serves as camouflage, with a white stomach to match the bright surface of the ocean (to fool oceanic predators from below) and a black coloration on their back that serves disguise them in the water from aerial predators. A common coloration theme unites the extant species such as, distinct spots on their abdomens, a small vertical stripe upon their black and a small patch of lightly feathered or nude patch of skin around its eyes that has a pink or whitish coloration (Cooper, 1977; Stefoff, 2005).
Compared to other genera within the spheniscids, the genus Spheniscusis moderately dimorphic, with size differences between the sexes (Livezey, 1989).
Spheniscus live between 10 to 27 years in the wild. Extinct members of the genus most likely fell within those natural lifespans (Crawford et al., 2001; Stefoff, 2005).
Members of the genus Spheniscus are coastal-dwelling predators and prey on small shoaling fish, such as anchovies (Engraulis capensis) and sardines (Sardinops sagax). Various crustaceans and cephalopods are also known to regularly fall prey to the banded penguin (Cunningham et al., 2008).
Natural predators of the genus Spheniscus include seals, feral cats, genets, leopards, mongooses and toothed whales. Eggs and chicks are also preyed upon by gulls and ibises. They also must compete with breeding space with many pinniped (e.g., seals) species (Crawford, et al., 2001; Randall and Randall, 1990; Stefoff, 2005).
Members of the genus Spheniscus are predators of small shoaling fish, including anchovies (Engraulis capensis) and sardines (Sardinops sagax). Various crustaceans and cephalopods are also known to regularly fall prey to the banded penguin.
A recent study has shown thatSpheniscusdemersus has a functioning sense of smell that assists them in finding and locking onto their specific prey items. This sensory aptitude was, until recently, unknown and significantly increases what we know about their foraging efficiency (Cunningham et al., 2008).
Extant members of the genus Spheniscus are noisy. African penguins (Spheniscus demersus) are also known by the common name "jackass penguins" because of the loud donkey-like sounds that they produce. The noise is for the distinct purpose of communication, and research has shown that there are three types of calls, the bray, the yell, and the haw. Each call is intended to communicate or serve a specific social purpose, to make contact, defend territory or attract mates, respectively. Spheniscus is a very social genus (Frost, et al., 2009; Thumser & Ficken, 1998).
The banded penguins are penguins that belong to the genus Spheniscus. There are four living species, all with similar banded plumage patterns. They are sometimes also known as "jack-ass penguins" due to their loud locator calls sounding similar to a donkey braying.[1] Common traits include a band of black that runs around their bodies bordering their black dorsal coloring, black beaks with a small vertical white band, distinct spots on their bellies, and a small patch of unfeathered or thinly feathered skin around their eyes and underdeveloped fluff sack that can be either white or pink. All members of this genus lay eggs and raise their young in nests situated in burrows or natural depressions in the earth.[2][3]
Banded penguins belong to the genus Spheniscus, which was introduced by the French zoologist Mathurin Jacques Brisson in 1760 with the African penguin (Spheniscus demersus) as the type species.[4][5] The genus name Spheniscus is derived from the Ancient Greek word σφήν (sphẽn) meaning "wedge" and is a reference to the animal's thin, wedge-shaped flippers.[6][7]
The four extant species of banded penguins (Spheniscus) are:
Several extinct species are known from fossils:
The former Spheniscus predemersus is now placed in a monotypic genus Inguza.
Scientists believe that the genus Spheniscus originated in South America, even though the oldest fossils assigned to the taxon are from Antarctica. The oldest Spheniscus fossils are also the oldest penguin fossils from Antarctica.[13] African, Humboldt, and Magellanic penguins all live in temperate climates. The African penguin lives in South Africa, the Humboldt penguin lives in coastal Peru and Chile while the Magellanic penguin lives in coastal Chile, Argentina, and the Falkland Islands. Humboldt and Magellanic penguins are partially sympatric, since their ranges overlap in southern Chile.[14][15] The Galápagos penguin is endemic to the Galápagos Islands, making it the most northerly of all penguin species.[16]
Banded penguins use vocalizations for localization, socialization and to allow recognition for conspecifics or mates.[17] Vocalizations in birds are produced by vibrations of the syrinx, located at the bottom of the trachea.[17][3] These penguins are sometimes referred to as "jack-ass" penguins, since their vocalizations tend to sound similar to a donkey braying.[1] Vocalizations in adult penguins can be classified into 4 distinct categories based on its acoustic properties and the behavioural context in which a vocalization is produced.[17] The 4 categories of vocalizations include contact calls, agonistic calls, ecstatic display songs or mutual display songs.[17]
Contact calls are vocalizations used primarily to maintain unity within a social group, to identify ones self and to maintain contact with a mate.[17] Vocal individuality has evolved in banded penguins due to their large social group sizes.[18] Contact calls are frequently used by banded penguins to form large flocks when foraging at sea.[17] It is easy to become separated while diving for food, therefore these penguins use contact calls to stay in contact with each other when they are out of sight.[17] A contact call can relay an excess of information about an individual penguin, including the penguins sex, age, social status within a group and emotional state.[19]
Agonistic calls are vocalizations used when a banded penguin is demonstrating agonistic behaviour, which is characterized by aggressive interactions or fighting.[3] Typically, banded penguins vocalize agonistic calls when defending a territory, such as their nest, against conspecifics.[17] For nesting penguin species, such as banded penguins, the mating pair and their offspring are the only individuals allowed on their nest.[20] Thus, any conspecific from the large colony that intrudes this territory will be a threat and an agonistic call will be produced.[20]
There are two types of display songs vocalized by banded penguins; ecstatic display songs and mutual display songs.[17] Ecstatic display songs are the loudest and most complex vocalization performed by banded penguins.[3] They are composed of a sequence of distinct acoustic syllables that combine to form a complete phrase and are often displayed during their breeding season.[3] Despite the close relatedness of banded penguin species, the ecstatic display calls of African, Humboldt and Magellanic penguins are distinctly recognizable, even to human listeners.[17] Typically, females respond more strongly to ecstatic display calls from their mates than from other conspecifics.[3] Furthermore, there is evidence to suggest that ecstatic display songs may convey vocal individuality through the type of syllables the song produces.[3] This vocal individuality can convey information such as body size and weight, since heavier penguins typically emit longer and lower-pitched vocalizations.[18] Mutual display songs are similar to ecstatic display songs in that they are also complex sequences of acoustic syllables. However, mutual display songs are performed by mates at their nesting site.[3]
The source-filter theory is a framework used for studying the communication of mammalian animals through vocalizations.[3] According to this theory, acoustic calls are produced by a source and then must be filtered to remove certain frequencies or leave others unchanged, which produces vocal individuality.[3] In mammals, the source is the vibrations in the larynx and the filter is the super laryngeal vocal tract.[3] However, birds use a different source and filter to produce vocalizations. They use a structure called the syrinx as their source of vibrations and their trachea acts as the filter.[3] The source-filter theory has become increasingly popular to study birds, such as various species of banded penguins. This theory can be used to investigate how acoustic variation and individuality within a set of closely related species is attributed to distinct morphological differences in their vocal organs.[3] The equivalence of the source-filter theory in humans is the source-filter model of speech production.
The banded penguins are penguins that belong to the genus Spheniscus. There are four living species, all with similar banded plumage patterns. They are sometimes also known as "jack-ass penguins" due to their loud locator calls sounding similar to a donkey braying. Common traits include a band of black that runs around their bodies bordering their black dorsal coloring, black beaks with a small vertical white band, distinct spots on their bellies, and a small patch of unfeathered or thinly feathered skin around their eyes and underdeveloped fluff sack that can be either white or pink. All members of this genus lay eggs and raise their young in nests situated in burrows or natural depressions in the earth.
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