The Little Blue Penguin ( Eudyptula minor ), also known as the Fairy Penguin or Blue Penguin, is the smallest of all penguin species. These diminutive seabirds are native to the coastlines of southern Australia, New Zealand, and the Chatham Islands. Their diet plays a crucial role in their survival and breeding success.
Physical Characteristics and Distribution
The name "Little Blue Penguin" comes from their distinctive plumage, which is indigo-blue and slate-grey, with white undersides from the chin to the belly. The head and upperparts of adults can vary from slate-blue to indigo-blue, or almost black, depending on their geographic location. They typically stand only 16 to 17 inches tall (41 to 44 centimeters) and weigh about 2 pounds (1 kilogram). Their flippers are blue, and they have a dark grey-black bill that measures 3-4 cm (1.2-1.6 in). The eyes are pale silvery- or bluish-grey or hazel, and their feet are pink above with black soles and webbing. Juvenile birds have lighter upperparts and a shorter bill.
These penguins are found in:
- New Zealand: The south and north coasts of the North Island, the southeast coast of the South Island, the west and southeast coasts of New Zealand Island, and Chatham Island.
- Australia: Mainland Australia, Tasmania, and islands off the coast of New South Wales.
Foraging Behavior
Adult Little Blue Penguins usually forage every day, traveling about 25 km (15.5 mi) from shore in shallow waters where prey is close to the surface. They leave land at dawn under cover of darkness, spend the day at sea foraging in small groups, and return to land at dusk, again under cover of darkness. If there is thick fog and low visibility, they remain offshore. During the breeding period, foraging can take two to three days while incubating eggs. During the non-breeding winter season, they may swim further from the colony. Prey is captured by pursuit diving to depths usually less than 20 m (66 ft). Small fish are swallowed head-first underwater; fish more than 3 cm (1.2 in) long are eaten at the surface.
Dietary Preferences
The diet of Little Blue Penguins varies seasonally and by location, but it primarily consists of small fish, cephalopods, and crustaceans. Key components of their diet include:
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- Fish: Anchovies, sprat, pilchards (sardines), and other small fish. The fish are usually less than 10 cm long and often post-larval or juvenile.
- Cephalopods: Squid, small octopus.
- Crustaceans: Krill, crab larvae, plankton.
In some locations, anchovy and sprat are preferred, while in others, sardines are the fish of choice. In still others, the preference is krill and sometimes squid. Like most penguins, they swallow their food whole.
Diet Variation by Location and Season
The specific composition of the Little Blue Penguin’s diet can vary significantly depending on its location and the time of year. For instance, a study of a Victorian population revealed a diet consisting of 76% fish and 24% squid. Nineteen fish species were recorded, with pilchard and anchovy dominating.
Since the year 2000, the diet of the Australian little penguins of Port Phillip has consisted mainly of Australian anchovies (the primary food source), barracouta, anchovy, and Gould's squid. Pilchards previously featured more prominently in southern Australian little penguin diets prior to mass sardine mortality events of the 1990s.
The Oamaru colony predominantly feeds on smaller schooling species such as sprat and gudgeon, while penguins from the Stewart/Codfish Island colonies more often hunt alone.
The Impact of Diet on Breeding and Survival
Food availability strongly influences the survival and breeding success of Little Blue Penguin populations across their range. Rising ocean temperatures have seen a trend towards earlier onset of breeding in Eudyptula minor which does not always align with the availability of their prey. Variation in prey abundance and distribution from year to year causes young birds to be washed up dead from starvation or in weak condition.
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During the breeding season, female Little penguins arrive in June to the breeding colonies and are met by raucous males who perform complicated courting displays. Peak egg laying time is generally June through August. They lay two eggs at a time which take approximately five weeks to hatch depending on the availability of food supplies.
Little penguins may have one, two, or even three broods (clutches) in a season. Nests are usually located in sheltered rock crevices but where these are not available they dig long burrows instead. Most Little penguins mate for life with both males and females incubating the eggs and caring for the young.
Threats to Food Supply
Several factors threaten the Little Blue Penguin’s food supply:
- Commercial Fishing: Competition from commercial fisheries in foraging areas for their food supply.
- Climate Change: Rising ocean temperatures and changes in prey distribution.
- Mass Mortality Events: Mass sardine mortality events can significantly reduce the availability of key food sources.
- Overfishing: The overfishing of species of preferred penguin prey has caused African penguin populations to decline.
- Pollution: Oil spills and plastic pollution can harm prey populations and contaminate the penguins' food sources.
Conservation Status and Threats
While the Little Blue Penguin is currently listed as a species of least concern by the IUCN, certain populations face significant threats. The small size of Little Blues and the proximity of their habitats to urbanization makes them especially vulnerable to a variety of significant threats resulting from human activities. These include predation by introduced mammalian species-weasels, foxes, ferrets, cats, and dogs. Uncontrolled dogs are a problem in urbanized areas where they roam popular beaches close to nesting sites. Feral cats have been responsible for extinction of one colony of Little Blues. Other threats on land include plastic pollution, roadkill, human harassment, tourism, and development destroying nesting sites. Their predators at sea include fur and leopard seals, killer whales, gulls, and White-bellied Sea Eagles. In addition to oil pollution, other human activities include being caught in fishing nets either as entanglement or by catch and competition from commercial fisheries in foraging areas for their food supply.
Conservation Efforts
Several conservation efforts are in place to protect Little Blue Penguins and their habitats:
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- Protection from Hunting and Egg Collecting: All 18 penguin species are legally protected from hunting and egg collecting.
- Habitat Management: Protecting and restoring nesting sites.
- Predator Control: Managing introduced predators such as cats, dogs, and rats.
- Oil Spill Response: Initiatives like Tasmania’s Penguin Jumpers Project, which provides sweaters for oiled penguins to help them maintain their body temperature and prevent poisoning.
- Fisheries Management: Implementing sustainable fishing practices to ensure an adequate food supply for penguins.