Comparison of penguin species

Please click on the diagrams for an enlarged view.

Weight

The Emperor Penguin is the heaviest among the penguin species (averages: male 36,7 kg; female 28,4 kg). The lightest penguin species is the Little Blue Penguin, the weight of both sexes is about 1 kg.
Generally, the male is heavier than the female. But the data of both Rockhopper Penguin species and the Macaroni Penguin show that the females have a higher weight than the males. It could be that above averaged females and below averaged males were weighted. Especially the sample size in the Southern Rockhopper Penguin is with 10 penguins per sex very low, so that it is not really representative. For a significant comparison more specimen are needed, so I cannot decide definitely which sex is heavier in these species.

Data information:
Reference: Penguins - Natural History and Conservation, edited by P. G. Borboroglu and P. D. Boersma, 2013, University of Washington Press
The specimen were weighted at arrival in colony, before courtship and before breeding (exceptions:in Yellow-eyed Penguins the weights of the nest guards are given. No information of measuring time in Erect-crested, African, Magellanic, Humboldt, Galapagos and Little Blue Penguins. In Royal Penguin I chose the mean of the range). There was no weight named for the female in Snares Penguin. If there were more weight data of different researchers, I calculated the mean and charted it in the diagram.

Size

The tallest penguin species is the Emperor Penguin, it can growth over one meter (in this source it is 117 cm). The Little Blue Penguin is the smallest (36 cm). The size of the most penguin species is between 50 and 70 centimeter. The male is generally taller than the female.

Data information:
Reference: Penguin Pedia, David Salomon, 2011, Brown Books Publishing Group
In this book only the range of the sizes of different penguin species are given. The values in the diagram above are the medium values between minimum and maximum.

Comparison of egg sizes

Genus Eudyptes (Crested Penguins)

Generally, Crested Penguins lay two eggs. As you can see in the diagram above the eggs vary in length and width. The second egg is bigger in all species of this genus. This so-called egg dimorphism leads to the fact that only one chick survives mostly. It is said that the weight difference between the first and second egg is up to 85% in Erect-crested Penguins.
In Erect-crested, Macaroni and Royal Penguins the chick of the first egg does not hatch at all, only the chick of the second egg could be strong enough to survive. In Fiordland and Snares Penguins the chick of the first egg does hatch but it mostly dies after a few days. If the conditions are good, the first chick could survive, too.
There is no definite explanation of this strange breeding behaviour. Researchers suggest that this strategy could be a prevention of predation. In New Zealand the weka (another flightless bird) often steals the eggs of the Macaroni Penguin. The probability that one chick survives could be higher with two layed eggs.

Data information:
Reference: Penguins - Natural History and Conservation, edited by P. G. Borboroglu and P. D. Boersma, 2013, University of Washington Press
The values in the diagram are the calculated means of the data of different researchers.

Genus Spheniscus (Banded Penguins)

Generally, Banded Penguins lay two eggs, but sometimes only one or up to three. You can also find differences in the first and second eggs in the species of this genus: the first egg is longer and narrower than the second egg which is shorter and broader. In contrast to the genus Crested Penguins there is no consequence in survival rate of the chick. Normally, both chicks hatch and are reared equally.

Data information:
Reference: Penguins - Natural History and Conservation, edited by P. G. Borboroglu and P. D. Boersma, 2013, University of Washington Press
The values in the diagram are the calculated means of the data of different researchers. There were no data given for Humboldt Penguins.

Population size and IUCN status

Last update of IUCN status: January 2022.
Source: website of IUCN Redlist

The Macaroni Penguin is the species with the biggest population size. However, the IUCN registrated this species as "vulnerable" on their Red List of Threatened Species because the population was declined by 30% in the last 10 years. The main reasons are human impacts, for example fisheries and changings in marine environments.
Due to a very narrow distribution area the Galapagos Penguin is listed as "endangered" by the IUCN. The population size is small and it can be reduced drastically because of natural catastrophes, the weather phenomenon el nino, climate change and increasing tourism.

King, Chinstrap and Little Blue Penguins are listed by the IUCN as "least concern". In the last time the population of King Penguins is increased and the population of Little Blue Penguins is stable. Actual studies point out that the population of the Chinstrap Penguins is declining. Possible reasons could be for example climate changes and fisheries. That is why the development of the population sizes of this species should be observed in the next time.

All in all the half of all penguin species are vulnerable or even endangered. That is why conservation in penguins is very important!

Data information:
References: Penguins - Natural History and Conservation, edited by P. G. Borboroglu and P. D. Boersma, 2013, University of Washington Press
Penguin Pedia, David Salomon, 2011, Brown Books Publishing Group
In the book only the estimated range of the individual and breeding pair numbers are given. The values in the diagrams above are the medium values between minimum and maximum.