From Penguins to Petrels: Why Antarctic Birds Matter Worldwide

New research reveals that most birds worldwide share similar traits, such as body size and diet. Yet, some stand out from the flock and many of them reside in the Antarctic. 

The Antarctic is well known for its captivating and unique birds. 56 species call Antarctica and the sub-Antarctic islands home, many of which are found nowhere else on Earth. Ranging from the iconic emperor penguin to the nomadic wandering albatross, these species have captured the attention of tourists and researchers alike for decades.

But how unique are Antarctica’s birds compared to those elsewhere, and what is their importance on a global scale?

A recent study published in Ecology Letters by Saxbee Affleck and Melodie McGeoch lends an answer to these questions. Seeking to describe the relationship between trait distinctiveness and geographic range size in the world’s birds, the research measured how similar species were in relation to their body size, diet, foraging strategy, dispersal ability, life span, clutch size and activity period – quantifying the trait distinctiveness of each species.

The findings revealed that most birds worldwide share many similar traits, such as similar body sizes and diets. Yet, some species stand out from the crowd due to their unique combination of characteristics. Many of these distinct birds inhabit the Antarctic.

Antarctica’s unique ensemble of birds

Not surprisingly, Antarctic birds display above-average trait distinctiveness compared to other birds worldwide. The challenging Antarctic and Southern Ocean environments have led these birds to evolve hardy adaptations for survival, which are reflected in their traits.

The scarcity of plants, especially on the Antarctic continent, limits available food sources. As a result, most Antarctic birds rely on fish, krill, or even other birds’ eggs or chicks, as seen with the notorious South Polar Skua. This scarcity of resources often limits the number of offspring each species can raise in a season.

Yet, 41 Antarctic birds have considerably widespread distributions and large populations. For instance, several albatross species, including the Black-browed and Grey-headed Albatrosses, inhabit multiple sub-Antarctic islands and vast areas of the Southern Ocean.

Sub-Antarctic islands also serve as occasional havens for visiting species not commonly observed in the Antarctic region. Cattle egrets, White-crested Elaenia, and Yellow-billed Pintails have been spotted on islands such as South Georgia and the Falklands, adding to the region’s bird diversity.

(Figure 1) Average position of Antarctic and sub-Antarctic island bird orders based on their global trait distinctiveness and geographic range size – adapted from Affleck and McGeoch 2024.

Why are Antarctica’s birds important globally?

The distinctive traits of many Antarctic species make them important among the world’s birds, especially when it comes to conserving global functional diversity.

Functional diversity captures the range of traits across all bird species, reflecting the ecological roles and functions they perform in their environments. Preserving this diversity is vital for maintaining healthy, resilient ecosystems worldwide.

Because many Antarctic birds have unique traits, few, if any, species elsewhere perform comparable roles, particularly within the Antarctic region itself. Losing these birds could harm not only Antarctic ecosystems but also reduce functional diversity at a global level.

However, as the triangular relationship between trait distinctiveness and range size identified in this study highlights, traits aren’t the only aspect that matters; species abundance is also vital.

Keeping common species common and distinct

Many Antarctic birds are not only distinct but also widespread and are, therefore, expected to have large populations. Because of the high number of individuals interacting with their environment and other species, these species are expected to have a greater overall impact within ecosystems.  

If these abundant yet distinct birds were to decline, we might observe significant shifts in ecosystems long before these species face extinction. Without other species with similar traits to “pick up the slack,” these impacts could happen even faster in Antarctica than elsewhere.

Antarctica’s birds illustrate why it’s essential to keep common species common, especially when they are also carrying a distinct set of traits. The persistence of these birds is crucial for maintaining global functional diversity and ensuring that Antarctic ecosystems remain resilient against global change.

The unique traits of these Antarctic birds have captured our attention and now call for our protection. 

Read more

Affleck, S. & McGeoch, M.A. (2024) Global avian functional diversity depends on the world’s most widespread and distinct birds. Ecology Letters 27, 10. https://doi.org/10.1111/ele.14552