Eudyptes robustussnares penguin

Geographic Range

Eudyptes robustus is restricted to Snares Island, south of New Zealand, and the adjacent ocean. Snares Island is a marine sanctuary that restricts access to humans (Muller-Schwarze 1984). (Muller-Schwarze, 1984)

Habitat

Eudyptes robustus lives in the temperate subantarctic subzone. This habitat provides enough vegetation for nest building and roosting. Snares Island is heavily forested, but the shores are rocky with mosses filling in the gaps. The main rock type is muscovite granite. The ground is cover to a depth of two meters with peat. This is the area where E. robustus builds its nests (Russ 2000).

Physical Description

As with the other five species of Eudyptes, E. robustus has characteristic yellow plumes or crests on the head (Muller-Schwarze 1984). Eudyptes robustus stands between 50 and 60 cm tall. They are physically similar to the Fjordland penguin (Eudyptes pachyrhynchus). They have a thick heavy bill, with white or pink skin around the base of the beak. They have all black feathers on their cheeks as opposed the white feather tufts on the cheek of the Fjordland penguin. Eudyptes robustus has broad crests that grow from the beak to the back of the head (Penguins Around the World 2000). Males and females are physically very similar, however the male is usually a little taller and weighs a little more.

  • Range mass
    3000 to 4000 g
    105.73 to 140.97 oz
  • Range length
    50 to 60 cm
    19.69 to 23.62 in

Reproduction

There are around 135 breeding colonies for E. robustus on Snares Island, with approximately two nests per square meter. These colonies produce an average of 44 fledglings per year. Breeding begins around age six. The reproductive cycle begins in the first three weeks of September.

The nests are created by digging shallow holes in the ground. These holes are lined with twigs and small branches. Eudyptes robustus builds the nest under trees and shrubs to shield themselves from the sun. If the vegetation is destroyed by storms the breeding grounds are moved (Penguins Around the World 2000).

The first egg is laid is usually small, then 4-5 days later a larger egg is laid. Both parents take turns incubating the eggs for the first 10 days. At this point the male goes to the ocean to feed the female who incubates the eggs for twelve days straight. When the male returns, the female goes to the ocean to feed and the male incubates the eggs for the next eleven days. The first three weeks after the chicks hatch, the male acts as a guard, protecting them from predators. Usually only one of every two chicks survive the guard stage. This high mortality rate is due to weather, primarily rainstorms. Predation and parasites are not significant sources of mortality. Approximately 75 days after hatching the chick goes to sea with the parents and then continues on its own (Muller-Schwarze 1984).

Behavior

Penguins show three types of behavior: general, aggressive, and sexual. General behaviors include huddling, in which the birds gather together to minimize heat loss, and preening, in which the bird gathers oil from a preening gland on the rump and applies it to the feathers. This is done to maintain the feathers and prevent water infiltration.

Aggressive behaviors include point and gape, in which the penguin points at an intruder and opens his bill, growling, to warn intruders that they are entering that penguin's territory. Another aggressive behavior is charging, in which the bird charges the intruder with its wings extended and beak open. This can be done silently or with a growl.

Sexual behaviors include the ecstatic display, in which the bird stands up right with its wings extended. The bird then repeatedly pumps its chest. This is done by single males to attract females. Bowing is done in pairs when the male returns to the nest. The female will bow to the male and then the male will bow to the female. The mutual display and trumpeting are both acts done when the male returns from an extended absence. These two behaviors are very similar. In the mutual display, the returning male will face the female, bow, and then extend his beak vertically in the air and call out. The female will then repeat the act. Trumpeting is the same act as the mutual display, except it is done with the pair standing side by side (Welch 1997).

Communication and Perception

Food Habits

The diet of the Snares Island Penguin is not well known, however, researchers believe that it is made up of krill, squid, and fish (Barham and Barham 1996). Fish makes up approximately 18% of its diet.

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Economic Importance for Humans: Positive

Because E. robustus has almost no contact with humans, it has no positive or negative impact on humans.

Conservation Status

At present, there are no conservation issues facing E. robustus. All 17 species of penguins are legally protected from hunting and egg collecting. There are no introduced land predators on Snares Island, however, researchers believe that the introduction of the Norwegian rat (Rattus norvegicus) could pose a serious problem. At present the only predators of adult E. robustus is the Hooker's sea lion. Eggs and chicks are subject to predation by brown skuas and giant petrels. Because the population is restricted to Snares Island, there is no danger from human contact (Sea World 2001).

Other Comments

There are currently 17 recognized penguin species. Scientists also recognize 32 species of extinct penguins.

Currently there are estimated to be between 25 and 35 thousand pairs of E. robustus living on Snares Island. The average penguin lives between 15 and 20 years (Welch 1997).

Contributors

Nick Bellows (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

tactile

uses touch to communicate

visual

uses sight to communicate

References

June 21, 2000. "Penguins Around the World" (On-line). Accessed March 23, 2001 at http://www.siec.k12.in.us/~west/proj/penguins/index.html.

Barham, P., B. Barham. June 29, 1996. "Pete and Barbara's Penguin Pages" (On-line). Accessed March 23, 2001 at http://ourworld.compuserve.com/homepages/Peter_and_Barbara_Barham/frame_ndx.html.

Muller-Schwarze, D. 1984. Behavior of Penguins. Albany, New York: University of New York Press.

Peterson, R. 1979. Penguins. Boston, MA: Houghton-Mifflin.

Russ, R. July 1, 2000. "Heritage Expeditions: Antarctic Expeditions" (On-line). Accessed March 23, 2001 at http://www.heritage-expeditions.com/snares.htm.

Sea World, March 17, 2001. "Penguins" (On-line). Accessed March 23, 2001 at http://www.seaworld.org/penguins/appendix.html.

Welch, K. 1997. "The Penguin Page: A Journey to the Bottom of the World" (On-line). Accessed March 23, 2001 at http://users.capu.net/~kwelch/pp/.