by Mike Bingham
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Humboldt PenguinSpheniscus humboldti
Breeding Range: Northern Chile & Peru
World Population: 12,000 breeding pairs
Humboldt penguins are only found along the Pacific coast of South America, from Isla Foca (5°S) off the coast of Peru, down to Algarrobo (33°s) in Chile, with additional isolated colonies further to the south on the Punihuil Islands (42°S). The total world population of Humboldt penguins currently stands at around 12,000 breeding pairs, with about 8,000 pairs in Chile and the remaining 4,000 pairs in Peru. The population is currently undergoing a serious decline, and the major causes are thought to be over-fishing of prey species, entanglement in fishing nets and commercial guano removal.
The Humboldt penguin is similar in size to Magellanic penguins, having an average length of around 70cm., and an average weight of 4kg. The plumage is also similar, except that the two white bands merge to form one thick band across the throat of Humboldt penguins. The eyes are reddish brown, and the bill is slightly larger than that of Magellanic penguins. The females are slightly smaller than the males, but have similar plumage.
Egg-laying can occur at any time of year between March and December, although two peaks of activity occur around April-May and September-October, depending on the locality. It is quite common for Humboldt Penguins to rear two successive broods in a single season, when conditions are favourable. This results in a yearly cycle which comprises of a 2 month moult period, followed by two 5 month breeding cycles. As a consequence, Humboldt penguins can be seen around their breeding sites throughout the year. As with all Spheniscids, Humboldt penguins strengthen their pair-bonding by allopreening.
Two equally sized eggs are laid with a 2-4 day interval, in burrows, rocky crevices or surface scrapes. Incubation takes about 40-42 days, with both adults changing incubation duties regularly. The major causes of egg loss are from flooding of nests during ocean storms, accidental breakage, nest desertion, and predation by gulls.
Chicks hatch about two days apart, and are fed on a daily basis, with adults leaving the colony in early morning, and returning with food later the same day. The time spent foraging for food increases as the chicks become larger, and require more food, but adults rarely forage more than 35 km from the nest site during chick-rearing.
Chicks remain within the nest until they have fully developed mesoptile plumage. Even then, chicks rarely stray far from the nest prior to fledging. The fluffy mesoptile plumage is browny grey above and creamy white beneath, and in conjunction with metabolic changes, it enables the chick to maintain its own body temperature. This allows both adults to leave the burrow to feed, in order to meet the ever increasing demands placed upon them by the growing chicks. When living in burrows, the chicks have no need to form creches in the way that surface breeding birds do.
The very arid climate in Perú and northern Chile means that Humboldt penguin nests are not generally at risk from being flooded by heavy rain, except at the colonies in Central Chile, where climate is more temperate with a rainy season in autumn and winter. Burrows close to shore are occasionally flooded by ocean swells.
The chicks fledge at about 10-12 weeks of age, and leave the breeding site for several months to forage at sea. The fledglings have similar markings to the adults, except that they are drabber and lack the black line down the sides of the abdomen. Breeding success rates can be very variable, but are generally in the range of 0.5 to 1 chick fledged per clutch. Adults show high pair fidelity, with most pair-bonds remaining unless one partner dies. They also show high site fidelity, with males showing higher site fidelity than females.
Once the second brood of chicks have fledged, the adults undertake a two week period of foraging at sea, before returning to undergo their annual moult in January and February, which lasts around three weeks. After the moult, adults again leave the colonies for about two weeks, to regain weight and condition, prior to returning to begin courtship once more. Humboldt Penguins are capable of breeding at 2 years of age, and can live to over 30 years of age in captivity, although few would achieve this in the wild.
Adults feed close to shore, taking various species of fish (Engraulis ringens, Sardinops sagax, Odonthestes r.regia, Normanichthys crockeri, Scomberesox sp.) squid (Todarodes fillippovae) and crustaceans. Most foraging is done at depths of less than 60m, often amongst weed beds, but they have been known to reach depths of up to 150m. Foraging rarely occurs more than 35km from the colony during the breeding season, but during the austral winter, birds may migrate several hundred kilometres from the breeding site before returning to breed again.
The coastline along which the Humboldt penguin is found is particularly susceptible to the influences of El Niño Southern Oscillation (ENSO) events, which occasionally bring seasons of extreme food shortage. During such years, cool nutrient rich waters which normally flow northwards along the coast of Chile and Peru, become displaced by warmer nutrient poor waters flowing from the central Pacific. This loss of nutrients results in a slowing down of primary production by phytoplankton, which in turn affects the entire marine food chain. Being top predators within the marine ecosystem, penguins are amongst the worst affected species, and often face complete abandonment of breeding, and even possible starvation. The Humboldt Penguins are particularly dependent on the availability of fish, which are forced to move further offshore in search of cooler currents.
Such events are often accompanied by severe weather patterns, which can bring heavy rain and flooding to areas that normally receive little or no rain. Under such conditions, Humboldt penguin breeding sites may be completely washed out, as happened along the coast of Peru and Chile during the ENSO of 1997/98.
In addition to natural predators, such as gulls, vultures, caracaras, foxes, pinipeds and cetaceans, Humboldt penguins also face a number of man-made hazards. Commercial fishing reduces breeding success and survival rates through depletion of food resources. Over-fishing of the Peruvian Anchovy (Engraulis ringens) led to its population collapse in the 1970s. This fish was a major component of the Humboldt penguins' diet, and penguin populations suffered as a result.
Hundreds of Humboldt penguins are also caught and drowned in the nets of local fishermen every year. Accidental entanglement in gill-nets, and the deliberate hunting of adults for food and fishing bait, are the main causes of adult mortality in some areas. Eggs are also taken from many breeding colonies, resulting in disturbance and reduced breeding success.
The breeding habitat of the Humboldt penguin is also damaged by human activity. The guano which builds up around certain breeding colonies due to the arid climate, is scraped off down to the bare rock for use as fertiliser, leaving nothing for the birds to burrow into. Introduced predators, such as wild dogs, also prevent successful breeding on many mainland sites, particularly at Punta San Juan in Perú, restricting most breeding populations to offshore islands or specially protected areas.
Unless mitigating measures are taken to reduce the impacts currently being exerted on this small population, the species will be extinct within a few decades.
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