Little Penguin

Written By: Valerie Grabski, Biology 487, Autumn 2009

littlepenguin

Photo by M. Kuhn

Eudyptula minor

STATUS (IUCN v3.1)
Least Concern
Little Penguins, with the exception of the White-Flippered, are numerous on both New Zealand and Australia. Although the population has been decreasing over the past century, new colonies have been established in urban areas, like St. Kilda Beach in Melbourne.

White-Flippered Penguins (E.m. alobsignata) are listed as Endangered. The White-Flippered Penguin is found only on the Banks Peninsula and nearby Motunau Island in New Zealand. The mainland population has declined by 60-70% since the 1960s. There has been a small increase on Motunau Island.

TAXONOMY

Number of subspecies: 6

Subspecies were originally determined by morphological differences relating to location, reinforced by genetic differences in the mtDNA between the different geographical regions. Little Penguins probably first evolved in New Zealand, migrated to Australia, and then some migrated back to New Zealand.

The White-Flippered Penguin (E. m. albosignata or E. albosignata albosignata) is considered by some to be a different species based on these genetic differences.

CONSERVATION CONCERNS

Most Little Penguin colonies are on offshore islands, as the impact of European settlement in Australia and New Zealand has had a detrimental effect on the population.

Introduced Species: The main land-based predators for the Little Penguins (including White-Flippered Penguins) are introduced species. In New Zealand mustelids, such as ferrets and stoats will prey on adults, chicks, and eggs. Feral cats and red foxes kill penguins and domestic dog attacks are deadly. Norwegian rats will feast on eggs, lowering already low breeding success rates. Predation by these animals has contributed to more than 75% of the mortality on Philip Island.

Climate Change: For most of the Little Penguin’s range, El Niño conditions have been shown to delay egg-laying and thereby decrease the number of penguins which can breed twice during the season. For Phillip Island, warmer sea-surface temperatures in March correlate to earlier egg lay-dates. The average lay-date at Phillip Island has been steadily getting later over the past four decades. In addition, wetter weather means more burrow collapse and therefore an increased chick mortality rate.

Fisheries: Although fisheries are not currently impacting prey availability, penguins get caught in near-shore set nets.

Other Human Activity: Although Little Penguins can live in urban environments, the colonies at St. Kilda and Sydney Harbor both number under 100 pairs. Where people are, automobiles and dogs pose a threat to the penguins. Oil spills, like the 1995 spill of the Iron Baron off the northern coast of Tasmania, are especially deadly. The number of penguins that died at sea is greater than is found in all but the largest colonies.

DISTRIBUTION

MAP2_GRABSKI_LITTLE

MAP1_GRABSKI_LITTLE

POPULATION TREND

TREND_GRABSKI_LITTLE

DESCRIPTIVE CHARACTERISTICS

LittlePenguin2

PLUMAGE

Head and back indigo-blue to slate grey, with the sides of the face and ear coverts a slate-grey blending into the white chin and throat. Front to the underside of the tail is white. Flippers are indigo-blue with a thin white trailing edge.

The white-flippered penguin is similar in coloration except that its flippers have thin white bands on both the leading and trailing edges, which in males may join across the flipper. Feet are white.

WhiteFlipperedPenguin

Photo by Aaron Jacobs

Eudyptula minor albosignata 

Juveniles are similar in color to adults, although lighter and brighter.

Chicks are covered in a brown-black down.

MEASUREMENTS

Although the average height of the Little Penguin is ~33 cm, all measurements vary for the different subspecies of Little Penguin.

E. m. novaehollandiae (Australian Little Penguin)

Males
Weight: 1.172 kg
Bill length: 3.77 cm
Bill depth: 1.4 cm
Flipper: 12.04 cm
Foot: 5.07 cm
Females
Weight: 1.048 kg
Bill length: 3.65 cm
Bill depth: 1.34 cm
Flipper: 11.73 cm
Foot: 4.81 cm

E. m. albosignata (White-Flippered Penguin)

Males
Weight: 1.357 kg
Bill length: 3.9 cm
Bill depth: 1.704 cm
Flipper: 12.6 cm
Foot: 5.45 cm
Females
Weight: 1.279 kg
Bill length: 3.63 cm
Bill depth: 1.541 cm
Flipper: 11.95 cm
Foot: 5.39 cm

VOCALIZATION

Adult penguins have three types of calls, contact, sexual, and agonistic. The contact call heard on land and at sea is short monosyllabic “huk huk”. Sexual calls which consist of a braying which ends in an inhalant squealing sound and is used by single males advertising at burrow entrances, during courtship between two mating penguins, and as greeting calls in mutual displays at nest sites. The most common agonistic call is a growl produced as the bird exhales. This can turn into a bray with an inhalant trill which becomes more defined as the bird becomes more provoked. Hisses, aggressive barks and yells are also heard.

Chick vocalizations consist of a “peep peep” that becomes more individualized as the chick ages. Full adult calls develop during chick molt.

BREEDING BIOLOGY

Little Penguins usually lay two eggs per clutch, with the second being laid within 2 to 7 days. They are more likely to be double-brooded (have two clutches) when the first clutch is laid early in the season. At some breeding sites 20-40% of breeding pairs are double-brooded.

Nest fidelity at Lion Island, NSW is 76% for females and 79% for males. Penguins arriving earlier in the season and that nest at Lion Island tend to have more breeding success. The divorce rate at Lion Island is 11% whereas at Philip Island, Victoria, Australia, it is 19%. There is a slight, but noticeable increase in separations following less successful breeding years. This may be because of the death of a partner.

This information is for Phillip Island and will vary from colony to colony:

CYCLE_GRABSKI_LITTLE

Average arrival date: Early September
Egg laying average date: October 10
Incubation: 40-42 days
Nest: Burrows, caves, bushes.
First egg weight: 53.67 g
First egg length: 5.583 cm
First egg breadth: 4.197 cm
Second egg weight: 53.48 g
Second egg length: 5.461 cm
Second egg breadth: 4.22 cm
Chick rearing period: 60-120 days
Fledgling period: November – December
Average annual reproductive success: 1.1 chicks/nest.
Age at first breeding: 2-4 years, females younger than males
Max lifespan: 20+ years
Average lifespan: 7 years
Molt: Adult molting lasts approximately 17 days, with the penguins losing about 1 kg of weight.

PREDATORS AND PREY

PREY

Little Penguins have a generalist diet made up mostly mid-water species of schooling fish, like Pilchard (Sardinops neopilchardus) or Australian Anchovy (Engraulis australis), as well as squid (especially Notosdarus gouldi) or krill Nyctiphanes australis). Years when Pilchards and Anchovies are scarce at Philip Island, juvenile Red Cod, Barracuda and Blue Warehou become important in the diet. Around Tasmania, blue grenadier are part of the diet.
The availability and the amount of effort put into catching prey can affect breeding success. Years with poor breeding success at Phillips Island are usually associated with the absence of pilchard in the diet.

PREDATORS

Feral animals and introduced species, including cats, dogs, mustelids and foxes prey on adults, juveniles, chicks and eggs. Large reptiles will also prey upon eggs and chicks. Predators on the Chatham Islands include Pacific gulls, sea eagles, kelp gulls and brown skuas. At sea, adults and juveniles are preyed upon by seals (particularly the New Zealand Fur Seal), and “sharks,” a term used in the literature to refer to any large-toothed fish. Juveniles and fledglings are more susceptible to parasites.

References