Spheniscus humboldti

Geographic Range

Humboldt penguins are endemic to the subtropical Pacific coasts of Chile and Peru. Their range extends from Isla Foca in the north to Punihuil Islands to the south. This area is located adjacent to the Humboldt Current, a large oceanic upwelling characterized by cold, nutrient rich waters.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Humboldt penguins spend a majority of their time in coastal waters. The amount of time the spend in water is associated with breeding status. Non-breeding penguins spend an average of 60.0 hours in the water before returning to land with the maximum trip lasting 163.3 hours. Breeding penguins spend less time offshore with trips averaging 22.4 hours with a maximum of 35.3 hours.

As is the case for many penguins, Humboldt penguins must come ashore to rest, breed, and raise young. The Pacific coast of South America is characteristically rocky and is also known for having large deposits of guano. Penguins will choose such sites for nesting but will occasionally use a cave along the shore.

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

• Aquatic Biomes
• coastal coastal

Physical Description

Humboldt penguins are medium-sized, ranging from 66 to 70 cm in length and weighing from 4 to 5 kg. They have blackish-gray feathers on the back and white feathers on the chest. Humboldt penguins have black heads with white stripes under the eyes that wrap around the side of their head and connect at the chin forming a horseshoe shape. Distinctive of the species is a solid, black breast band that helps to differentiate them from Magellanic penguins ( Spheniscus magellanicus ). The solid breast band also helps in distinguishing adults from juveniles who have a darker head.

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

• Sexual Dimorphism
• male larger

Reproduction

Humboldt penguins are monogamous and recognize their partner in the colony through distinct vocal cues. Although they are typically monogamous, in rare cases the female will solicit another male for mating. Extra-pair mating is always initiated by the female but the costs and benefits of this strategy are not well understood.

Another rare aspect of the mating of Humboldt penguins is that males may start usurps, defined as an unpaired male that invades the nest of an established pair. While this strategy is used to gain mates, there is risk of injury and even death of the invader. A situation that might make usurpation favorable includes periods of low food availability that are characteristic of El Niño events. Research has shown that females are disproportionately effected at these times leading to male-biased sex ratios. With more males losing mates to mortality, the rate of usurpation may increase.

• Mating System
• monogamous monogamous

Humboldt penguins can reproduce nearly all year long due to the relatively warm onshore climate in the region they occupy. Breeding takes place between March and December with peaks in April and August to September. Before reproduction occurs penguins will molt. During molting, penguins stay on land and are in a fasting state for about two weeks. They will then go to sea to feed before returning to the breeding grounds to mate.

Humboldt penguins use covered nests that protect their eggs from both intense solar radiation, and aerial and terrestrial predators. Oftentimes penguins use the thick deposits of guano found on the shore line to create their nests. They create burrows and deposit their eggs safely inside. Females lay two, similar sized eggs per clutch. After the eggs have been laid the male and female will share the duty of attending to the nest for the full extent of the approximately six week incubation period.

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

As mentioned previously, both sexes watch and protect the nest before hatching occurs. After the eggs have hatched, the parents share in the responsibility of feeding the chicks. Adults must provide enough food at frequent intervals for chick survival but his must be balanced with self maintenance. This balance is met by switching between short foraging trips in order to feed the chicks and longer trips for maintenance. Taylor et al. (2001) showed that penguins raising chicks generally forage during the day and make short, shallow dives. Once molting occurs, which marks the beginning of the juvenile stage, offspring will go into the ocean to forage on their own and are fully independent.

• Parental Investment
• 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

There is little known about the lifespan of Humboldt penguins. Information from the wild is lacking, but Sea World reports that penguins live between 15 to 20 years in their facilities. It is thought that captive penguins will live longer than wild penguins because captive penguins do not deal with predators and also receive a healthy, balanced diet. It is also noted that less than half of chicks make it past their first year of life.

Behavior

Humboldt penguins typically molt in January. Studies have shown that this behavior is correlated with a spike in thyroid hormones at the same time that sex steroid hormones are at their lowest concentration. Molting is the process of replacing old worn feathers with new ones. For penguins this is extremely important as they need their feathers for insulation and to seal water out. Over the two week period that molting is occurring, the penguins will fast because they are unable to enter the water to forage.

Humboldt penguins have been found to be extremely sensitive to human presence. Their breeding success was significantly reduced at sites that were highly visited by tourists. Heart rate drastically increased with the presence of a human at 150 meters away and it took 30 minutes for the penguin to recover. This sensitivity to humans may be due to a history of being hunted.

Humboldt penguins live in large colonies and are considered highly social except during foraging. Foraging behavior is dependent on whether the adult penguin is raising chicks or not. Penguins not raising fledglings are able to explore different foraging habitats that are further away because they are able to be away from the colony for longer periods of time. Penguins raising fledglings rarely take overnight foraging trips and generally exhibit a shallower, shorter dive.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• colonial colonial

Home Range

Satellite monitoring of free ranging Humboldt penguins shows has found that 90% of all satellite locations came from a range of 35 km around their breeding ground with maximum distances of 100 km. These values increase during El Nino events. Penguins will abandon their nests and may forage up to 895 km offshore. These results contradicts an earlier hypothesis that Humboldt penguins are primarily sedentary and remain close to the breeding ground year round.

Communication and Perception

Individuals have vocalizations that are unique and distinguishable by mates. Humboldt penguins display three calls which include the contact call, the display call, and a threat call. In recent studies, Humboldt penguins have been found to have an acute sense of smell. Odors create learned preferences to parental smells in chicks and are thought to play a role in social and family interactions. It is hypothesized that because of natal philopatry, selection favors kin recognition in order to avoid incest with siblings that were born in different years and are therefore unfamiliar. Humboldt penguins explore unfamiliar scents but will return to a familiar scent and prefer it. Therefore, prior association of a scent likely allows for recognition of nest-mates or colony mates. Familiar scents may also be associated with locating burrows at night.

Humboldt penguins are believed to use the same visual mechanisms as other penguins. They cannot perceive prey under low light conditions. They accommodate by decreasing the radius of curvature of the anterior surface of their lens. They can see equally as well in the air and the water. The loss of corneal power under water is mitigated by having a flat cornea and a spherical lens. This is also aided by accommodation. It was once believed that penguins were myopic in air but evidence from current studies contradicts this.

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

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

Food Habits

Humboldt penguins specialize on pelagic schools of fish. Penguins located in the northern regions of Chile ate almost exclusively garfish those found in central Chile preferred anchovy, pilchard, and squid. The difference is believed to be due to the availability of the different prey types in the particular foraging regions. Additionally, Humboldt penguins consume Araucanian herring and silversides.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore

• Animal Foods
• fish

Predation

In the ocean, Humboldt penguins are predated on by sharks, fur seals, and sea lions. On land, the nests are preyed on by feral cats, dogs, foxes, snakes, and rodents. In some cases, these predators attack a juvenile or adult Humboldt penguin if it is of smaller size. Insular penguins lack anti-predatory tactics to rats and feral cats due to their recent introduction of these predators on islands by humans. To a lesser extent, gulls are also known to predate nests. Humboldt penguins use guano to create burrows for their eggs that help to reduce exposure to predators. The large colonies that Humboldt penguins live in also provide defense by number. In the water, their main defense is their ability to swim quickly and with agility.

Ecosystem Roles

Humboldt penguins are one of the main predators in the Humboldt current system.

Economic Importance for Humans: Positive

Humboldt penguins were considered an important source of guano. Guano is a rich fertilizer and a major source of income for the Peruvian government.

In recent years, ecotourism has begun to focus on the species. However, Humboldt penguins are shy and acutely sensitive to human presence. In 2010, regulations were established to assist with breeding success while maintaining tourist activity.

• Positive Impacts
• ecotourism ecotourism
• produces fertilizer

Economic Importance for Humans: Negative

There are no known adverse effects on humans.

Conservation Status

The major factors contributing to decreases in Humboldt penguin populations are fishery activity and human disturbances. Penguins are at risk of entanglement and drowning in fishing nets while fisheries threaten food availability. Guano extraction has also reduced the breeding success of penguins. Guano reserves are being formed in order to reduce this threat to population viability.

Additional Links

Encyclopedia of Life

Contributors

Heidi Nissley (author), Indiana University-Purdue University Fort Wayne, Mark Jordan (editor), Indiana University-Purdue University Fort Wayne, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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