The penguins of Antarctica

Author

Selina Baldauf

Published

October 16, 2025

1 Introduction

There are three main penguin species in Antarctica (Chinstrap, Gentoo, Adelie). You can see them in Figure 1:

Figure 1: Illustration of the three penguin species by Allison Horst

In this paper we want to answer the following questions

  1. How bill depth depends on bill length?
  2. Which penguin species has the highest body mass?

2 Methods

All analysis was done using R version 4.1.3 (R Core Team 2022) and Quarto (Allaire 2022)

2.1 The data

The data was collected on islands in Antarctica and published by Gorman, Williams, and Fraser (2014). You can find the original paper with the title “Ecological sexual dimorphism and environmental variability within a community of Antarctic penguins (genus Pygoscelis)” (Gorman, Williams, and Fraser 2014) in PLoS ONE1

The data is published via the palmerpenguins R package (Horst, Hill, and Gorman 2020) which you can find on this website.

The data contains (among others) the following measurements:

  • bill length
  • bill depth
  • body mass
  • sex
    • male
    • female

2.2 The analysis

We did some plots, calculated some summary statistics and a linear model of the form \(y = ax + b + \epsilon\)

3 Results

The mean weight of all penguin species is 4201.754386 g. Gentoo penguins have an average weight of 5076 g, Adelie penguins of 3701 g and Chinstrap penguins of 3733 g.

Figure 2 below shows that Gentoo penguins have the highest body mass.

Figure 2: Histogram of weight of the three penguin species.

There is a positive relationship between bill length and bill depth for all 3 species, as Figure 3 shows.

Figure 3: Scatter plot with regression lines showing the relationship between bill length and bill depth for the 3 penguin species

In general, it looks like the body characteristics differ between the sexes but also between the penguin species, as Table 1 below illustrates:

Table 1: A summary of the penguin data
species sex bill_length bill_depth flipper_length body_mass
Adelie male 40.39041 19.07260 192.4110 4043.493
Adelie female 37.25753 17.62192 187.7945 3368.836
Gentoo female 45.56379 14.23793 212.7069 4679.741
Gentoo male 49.47377 15.71803 221.5410 5484.836
Chinstrap female 46.57353 17.58824 191.7353 3527.206
Chinstrap male 51.09412 19.25294 199.9118 3938.971

4 References

Allaire, JJ. 2022. “Quarto: R Interface to ’Quarto’ Markdown Publishing System.” https://CRAN.R-project.org/package=quarto.
Gorman, Kristen B., Tony D. Williams, and William R. Fraser. 2014. “Ecological Sexual Dimorphism and Environmental Variability Within a Community of Antarctic Penguins (Genus Pygoscelis).” Edited by André Chiaradia. PLoS ONE 9 (3): e90081. https://doi.org/10.1371/journal.pone.0090081.
Horst, Allison Marie, Alison Presmanes Hill, and Kristen B Gorman. 2020. Palmerpenguins: Palmer Archipelago (Antarctica) Penguin Data. https://doi.org/10.5281/zenodo.3960218.
R Core Team. 2022. R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing. https://www.R-project.org/.

Footnotes

  1. paper available here.↩︎