The Humboldt penguin (Spheniscus humboldti) is a medium-sized penguin. It resides in South America, along the Pacific coast of Peru and Chile. Its nearest relatives are the African penguin, the Magellanic penguin and the Galápagos penguin. The Humboldt penguin and the cold water current it swims in are both named after the explorer Alexander von Humboldt. The species is listed as vulnerable by the IUCN with no population recovery plan in place. The current wild population is composed of roughly 23,800 mature individuals and is declining. It is a migrant species.
Humboldt penguins nest on islands and rocky coasts, burrowing holes in guano and sometimes using scrapes or caves. In South America the Humboldt penguin is found only along the Pacific coast, and the range of the Humboldt penguin overlaps that of the Magellanic penguin on the central Chilean coast. It is vagrant in Ecuador and Colombia.C. Michael Hogan (2008) Magellanic Penguin, GlobalTwitcher.com, ed. N. Stromberg The Humboldt penguin has been known to live in mixed species colonies with the Magellanic penguin in at least two different locations at the south of Chile.
The Humboldt penguin has become a focus of ecotourism over the last decades.
Etymology Both the Humboldt penguin and the Humboldt current were named after Alexander von Humboldt. It is known in Peru as the , which translates to "baby-bird", due to their waddling gait and flightless wings held out suggesting the image of an infant toddling on the beach. Distribution and habitat The Humboldt penguin is endemic to the west coast of South America.
The Humboldt penguin's breeding distribution ranges from southern Chile along the dry and arid coastal regions of the Atacama Desert to subtropical Isla Foca in north Peru. Its range is restricted to the coast and offshore islands affected by the Humboldt current, which provides a continuous supply of nutrients and food, thus supporting huge populations of seabird. In Chile, the most important breeding colony is at Isla Chañaral.
In July 2002, a Humboldt penguin was caught in a fishing net off the coast of Prince of Wales Island in Alaska. The penguin was released from the net, and eventually sent back to the water by one of the fishermen. This is the first and only record of a penguin in the wild in North America. It is unknown whether the penguin was a wild penguin or an escaped pet or zoo animal. Description Humboldt penguins are medium-sized penguins, growing to long and a weight of . The sex of the Humboldt penguin cannot be recognised via differences in plumage, as they are monomorphic. The male is heavier and larger than the females. Their sex can be determined via head width and bill length; the male has a longer bill than the female. While all the Spheniscus penguins are close to each other in size, the Humboldt penguin is the heaviest species in the genus, with 123 females weighing on average and 165 males averaging . Humboldt penguins have a black head with a white border that runs from behind the eye, around the black ear-coverts and chin, and joins at the throat. They have blackish-grey upperparts and whitish underparts, with a black breast-band that extends down the flanks to the thigh. They have a fleshy-pink base to the bill. Juveniles have dark heads and no breast-band. They have spines on their tongue which they use to hold their prey.Penguins of the World.- By Wayne Lynch. 2007. 2nd Edition. Firefly Books Ltd., Richmond Hill, Ontario, Canada.
Vocalisation The Humboldt penguin has different calls that it uses to communicate in different ways. The function of its calls are consistent among Spheniscus species. If an individual comes too close to an adult Humboldt penguin, the Yell is a warning call which is followed by pecking or chasing if ignored. A higher density of penguins leads to more territorial and aggressive behaviours, which leads to more Yells. The Throb is a soft call between pairs at the nest, used by incubating birds when their mates return to the nest. The Haw is a short call given by juveniles alone in the water and by paired birds when one is on the water and the other is on land. It has significant individual variation in duration and frequency. The Bray is a long call used to attract a mate and advertise a territory during the pre-laying and pre-hatching periods. It is an individually distinct call in all variables: syllables per call, duration, inter-syllable intervals, duration of syllables and frequency. When calling, the bird points its head upwards and flaps its flippers slowly. The Courtship Bray is similar to the Bray, however a different posture is assumed and is given synchronously by pairs during the pre-laying period: the birds stand together pointing their necks and head up, with flippers out to the side. The Peep is given by chicks begging for food.
Moulting
Most penguins moult between mid-January and mid-February, however the initiation varies with latitude and favourable conditions such as food abundance. Humboldt penguins are confined to land until they finish moulting. They become hyperphagic during the pre-moulting period. The feathers are lost and replaced within 2 weeks.
Ecology Diet The Humboldt penguin feeds predominantly on pelagic schooling fish. The consumption of cephalopods (namely Antarctic flying squid) and crustaceans vary between populations. Northern colonies consume primarily Atlantic saury and garfish, whilst southern populations primarily consume anchovy, Araucanian herring, silver-side, pilchard and squid. There are seasonal differences in the Humboldt penguin's diet that reflect the changes in availability of fish species across seasons.
Foraging behaviour
The Humboldt penguin is a visual hunter. Humboldt penguins leave their islands for foraging after sunrise and different populations have different preferred foraging distances from the colony. Their foraging rhythm depends on the light intensity. They spend more time foraging during overnight trips. Fish are mostly seized from below through short, shallow dives.
The foraging range of Humboldt penguins is between from Pan de Azúcar, with 90% of the foraging being from a range of around the island and 50% from a range of . The maximum depth reached is .
Failed breeders take longer foraging trips with longer and deeper dives. They also dive less often than breeding penguins.
Courtship During courtship, the Humboldt penguins bow their heads to each other and exchange mutual glances with each eye, alternatively. In the ecstatic display to attract a partner, the bird extends its head vertically, collapses its chest, flaps its wings and emits a loud call resembling the braying of a donkey. The mutual displaying consist of the pair standing side by side and repeating the actions of the ecstatic display.
Reproduction
The Humboldt penguin nests in loose colonies, with most pairs laying two eggs of the same size 4 days apart that require 41 days of incubation. Their breeding schedule is adjusted depending on the abundance of food. They breed immediately after moulting, when food is abundant and solar radiation is reduced.
The Humboldt penguin lay eggs from March to December, but also with peaks in April and August–September, due to individuals having a second clutch. Half of the females successfully have two clutches per year and most were double broods. If pairs lose their eggs during the first breeding season, they lay a new clutch within 1–4 months. The incubation shifts last, on average, 2.5 days, before one parent takes over and allows the other to forage. There are no differences in the contribution to provisioning from the male and female parents.
Chicks hatch generally 2 days apart. Chicks are semi-altricial and nidicolous and guarded by one parent while the other forages. Chicks are fed only once every day. Chicks are left unattended at the nest site after a certain age and both parents forage simultaneously.
Breeding sites The historical breeding sites of this species are burrows on guano layers. Nests of the Humboldt penguin can also be found at caverns, hollows, cliff tops, beaches and scrapes covered by vegetation. They also nest at few Peruvian islands where true soil can be found for digging. The majority of penguins breed on cliff tops.
Migration Humboldt penguins are sedentary during the breeding season, staying in proximity to their nests and show fidelity to breeding site. They can cover large distances, particularly in response to food shortages or changes in environmental conditions.UNEP (United Nations Environment Programme). (2003). World Conservation Monitoring Centre report on the status and conservation of the Humboldt penguin Spheniscus humboldti. United Nations Environment Programme World Conservation Monitoring Centre, Cambridge. They are a true migrant between Peru and Chile.
Threats
El Niño-La Niña dynamics The ecosystem of the Humboldt current is affected by the El Niño phenomenon. During the El Niño, upwelling of nutrient-rich bottom water in the south-eastern Pacific Ocean is depressed, as well as sea surface temperature anomaly (SSTA) value increases. Massive mortality, especially of juveniles, nest desertion and lack of reproduction occurs. Humboldt penguins migrate south as marine productivity decreases, following the anchovy stocks. Humboldt penguins expend more time and energy foraging as SSTA increases.
Fisheries The estimated energetic demands of the total Humboldt penguin population during breeding season sums up to 1,400 tons of fish. The Humboldt penguin depends on commercially exploited, schooling prey species including anchovies. This makes them susceptible to changes in prey availability due to overfishing. They are also susceptible to entanglement in fishing nets.
Human presence
Humboldt penguins are extremely sensitive to human presence, with little habituation potential. Passing at a distance from an incubating Humboldt penguin provokes a response, which is the greatest response distance reported for penguins to date, making it the most timid penguin species so far studied. Humboldt penguins need up to half an hour to recover to normal heart rates after human approach, however, this time decreases with repeated visitation. Cumulative stress by frequent visits and delayed return of foraging partners leads to nest desertion, consequently causing decreased breeding success at frequently visited sites.
Habitat disturbance and feral species The introduction of feral goats on the Puñihuil islands had a detrimental impact on the Humboldt penguin population. The feral goats browse the vegetation the penguins use to build their nests and they can lead to collapse to dirt burrows. The connection of the island to the mainland also led to the movements of mammals onto the island.
In central Chile, European rabbits and Norway rats graze on the vegetation. Norway rats and black rats also predate on eggs. Feral cats and dogs consume chicks, fledglings and adult Humboldt penguins.
Industrial development Some Humboldt penguin colonies face emerging pressures from industrial development; the construction of coal-fired power plants and mining proposals in Chile. Peru's largest colony faces the prospect of a major new industrial port in close proximity to the country's largest colony, at Punta San Juan. Oil spills have previously impacted some colonies. The colony of 800 birds at Cachagua was exposed to two oil spill events in 2015–16. Oil spills related to port and shipping activities have impacted many species of penguins across the southern hemisphere.