Spheniscus mendiculus

Geographic Range

Spheniscus mendiculus is found on the Galapagos Islands, off the western coast of Ecuador. Spheniscus mendiculus is a year-round resident of the majority of the 19 islands in the Galapagos chain. Most individuals are found on the two larger islands of Fernandina and Isabela.

• Biogeographic Regions
• neotropical neotropical
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Galapagos penguins occupy coastal areas and offshore waters where the cold Cromwell Current brings food and other population-sustaining necessities into the vicinity. These birds rest on sandy shores and rocky beaches and nest on areas of sheltered coast. Galapagos penguins primarily breed on the larger islands of Fernandina and Isabela where they lay eggs in caves or holes found in the volcanic rock of the islands. When feeding, they will hunt for small fish and crustaceans in the coastal waters, diving to a depth of approximately 30 m.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial
• saltwater or marine saltwater or marine

• Terrestrial Biomes
• desert or dune desert or dune

• Aquatic Biomes
• coastal coastal

• Other Habitat Features
• caves

Physical Description

Galapagos penguins are fairly small penguins, averaging only 53 cm in height and ranging in weight from 1.7 to 2.6 kg. Sexual dimorphism exists, in that males are slightly larger than females. Galapagos penguins are the smallest members of the Spheniscus or "banded" penguins . Members of this species are mainly black in color with white accenting colors on various locations of the body and a large white frontal area. As in all banded penguins, the head is black with a white mark that begins above both eyes and circles back, down, and forward to the neck. They have the narrowest head-stripe of the banded penguins, a factor that distinguishes them from the similar Spheniscus magellanicus . Below the head stripe, S. mendiculus has a small black collar that merges into the back. Below the black collar there is another white stripe that runs the length of both sides of the body, followed by a black stripe that also runs the length of the body.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Breeding in Galapagos penguins involves a fairly complex set of courtship rituals before copulation occurs. First, male Galapagos penguins must locate a mate if they do not already have one. Since these penguins generally copulate with the same mate throughout their lifespan, each year only a handful of adult penguins need to attract a new mate. Those that are searching for a new mate exhibit various courtship rituals that attract a mate and strengthen the bond between the two partners. Paired individuals also participate in courtship rituals that enhance the pair bond. Such courtship rituals include displays of mutual preening, flipper patting, and bill dueling. After finding a mate, but before copulation, each penguin pair builds a nest that is continuously renovated until the eggs are laid. When the complex courtship and initial nest building are complete, the penguins begin mating. In Galapagos penguins, as in all other penguins, mating involves a balancing act in which the male climbs upon the back of the female that is sprawled upon the ground on her stomach. Once on top, sometimes after several tries, the male and female copulate--the process usually only takes about one minute. Steady copulation usually begins to occur early before the first egg is laid. As egg laying draws closer the penguins may copulate more frequently, mounting up to 14 times a day. Once the eggs are laid, both male and female S. mendiculus care for the young, including incubating the egg, fasting, and foraging for food. This reproductive process occurs every time a pair of Galapagos penguins mate, up to two or three times a year.

• Mating System
• monogamous monogamous

Galapagos penguins breed two to three times a year, producing two eggs per clutch. As the breeding season lasts year round, most breeding occurs whenever coastal waters are cold enough and abundant with food supplies. These factors, necessary for breeding, occur most often between May and July, thus prompting most of the breeding of Galapagos penguins to occur during these months. However, as climatic changes are unpredictable, breeding can occur at any time of the year when conditions are favorable. Galapagos penguins construct nests in caves or volcanic-formed cavities before copulation takes place. At egg-laying Galapagos penguins incubate their eggs, which lasts from 38 to 42 days. After hatching, the same process of caring for the chick and foraging for food continues. Chicks fledge at approximately 60 days and are fully independent within 3 to 6 months. Female Galapagos penguins must wait another 3 to 4 years to reach sexual maturity while males must wait another 4 to 6 years.

Their nesting behavior is unique. Galapagos penguins will make their nests out of any resources that are available and often steal pebbles, sticks, and other components from a neighboring nest when the inhabitants are not present.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Parental investment of Galapagos penguins is divided between both males and females. Incubation duties are shared and, when one incubates, the other ventures to coastal waters to forage for food. Similarly, at hatching, one parent broods and guards the newly-hatched chick while the other forages for food to nourish itself and the chick. The foraging parent returns with food to regurgitate for the chick. This intense guarding and feeding process occurs for about 30 to 40 days, at which point the chick has grown substantially and can then be left alone for periods of time while the parents forage. This post-guarding period generally lasts about one month, at its completion the chick will have completed its growth into an adult penguin.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

Galapagos penguins can live for 15 to 20 years. Because of high mortality rates due to predation, starvation, climatic events, and human disturbance, most Galapagos penguins do not live to such ages.

Behavior

Galapagos penguins are social animals that live in large colonies. By living in large colonies, these penguins can take advantage of group hunting and deterring predators. These penguins are awkward on land as a result of their short legs and small wings that provide little balance. When walking, Galapagos penguins waddle with outstretched wings. They are agile swimmers.

• Key Behaviors
• terricolous
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• colonial colonial

Home Range

Spheniscus mendiculus is endemic to the Galapagos archipelago. Galapagos penguins roam for food within the coastal waters of these islands, but specific home ranges are not reported. Galapagos penguins live in colonies and are territorial, protecting their nesting area from neighbors. Territory size depends on population density.

Communication and Perception

Galapagos penguins rely on a series of vocal calls and sounds as well as a complex array of body movements for varying communication purposes. Vocalizations are crucial in helping to identify mates and chicks. These calls, along with body movements such as wing-flapping, help to deter egg-snatching predators. In courtship rituals, S. mendiculus relies heavily on displays and postures that advertise sexual status (paired or not paired), help to attract a mate, and reinforce the bond between the pair. Spheniscus mendiculus also uses vocalizations and body movements for general communication, such as greetings and displays of emotion.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• duets duets

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Galapagos penguins are carnivorous and eat all types of small fish (no longer than 15 mm in length) and other small marine invertebrates. Prey species include anchovies ( Engraulidae ), sardines and pilchards ( Cleupidae ), and mullets ( Mulgilidae ). Galapagos penguins use their short wings to swim through the water and their small, stout beaks to capture small fish and other small marine organisms. Galapagos penguins usually hunt in groups and capture small prey by seizing them from below. The position of their eyes in relation to the beak means that they see prey best from a position below the prey.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods

• Animal Foods
• fish
• mollusks
• aquatic crustaceans
• other marine invertebrates
• zooplankton zooplankton

Predation

Galapagos penguins lay their eggs in caves or holes in the volcanic rock, reducing predation on their eggs. They also vocalize, attack, and use body movements (wing-flapping, vocal calls, etc.) to frighten away predators. This is most effective when a group of penguins confronts a predator. Predators on young penguins include rats, crabs, and snakes. As adults, Galapagos penguins are preyed on by hawks and owls, as well as feral cats and dogs. When foraging for food in the water, Galapagos penguins are preyed on by sharks and other large, marine animals. The pattern of black and white countershading on their body makes them difficult to see underwater. A predator looking from above will see a black-colored backside of the penguin that blends in with the darker, deeper water. A predator seeing the penguin from below will see a white underside that blends with the lighter-colored, shallow water.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Galapagos penguins are major predators of small fish and other marine invertebrates in the coastal waters of the Galapagos. They also act as prey for marine and avian predators in the Galapagos.

Economic Importance for Humans: Positive

Galapagos penguins provide economic value to humans who use this species and its coastal habitat to promote ecotourism. Many tourists and avid birdwatchers will pay to travel and visit the habitats of the Galapagos penguins.

• Positive Impacts
• ecotourism ecotourism

Economic Importance for Humans: Negative

Galapagos penguins may cause minor economic harm to the seafood industry for humans. As S. mendiculus relies heavily on a diet of small fish, such as anchovies and sardines, collectively the species can have an effect on the number of small fish available to catch for human consumption in their range. It has been shown that a penguin population can eat upwards of 6,000 to 7,000 tons of food locally, approximately 3,000 tons of that total has some economic value to humans.

Conservation Status

According to the IUCN Red List and the United States Endangered Species Act, Galapagos penguins are currently listed as endangered. Due to climatic changes brought about by El Niño and La Niña cycles, the food supply available to the Galapagos penguins varies greatly. These unpredictable shifts in food supply often lead to starvation and deaths and a substantial decline in the already dwindling penguin population. Furthermore, human disturbances and predation are major factors contributing to the decline of S. mendiculus . Human disturbance is the main cause for ecosystem harm that affects the nesting grounds of Galapagos penguins. Few efforts are underway to protect S. mendiculus . However, recently the Galapagos Conservation Trust launched the Sylvia Harcourt-Carrasco Bird Life Fund for Galapagos that will aim much of its efforts at conserving the population of Galapagos penguins. This fund provides a push for the conservation of S. mendiculus that may lead to other conservation actions, and eventually to a restored, healthy population.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Joshua Wahlstrom (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

References

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