Thought Leaders

Introduced Bird Species are Failing to Replace Extinct Bird Roles

Thought LeadersFerran SayolMarie-Curie Postdoc Fellow University College London

AZoCleantech speaks to Ferran Sayol from University College London who has researched human effects on bird biodiversity. Sayol details his recent study looking at how introduced bird species are failing to replace the roles of extinct birds.

How did you begin your research into human-caused extinct bird species?

This research was part of a project funded by the Swedish Research Agency (Skatteverket) to Søren Faurby, aiming to understand how human impacts can bias our understanding of biodiversity patterns. I started as a postdoc in this project in 2018 and started to gather information on human-caused bird extinctions.

What is the current extent of bird species extinction?

We have compiled records of more than 600 bird species that have potentially gone extinct because of humans. Currently, there are about 10,000 extant birds, but around 14% of them are threatened with extinction.

What are the main causes of extinction in birds?

The main causes are habitat destruction, direct persecution (i.e., hunting) and invasive species such as cats or rats. This later threat is especially important on island birds, as they have evolved in an ecosystem lacking mammal predators.

What direct consequences occur due to bird extinctions?

One consequence of bird extinctions is the loss of some ecological functions. For instance, the extinction of nectarivores might then cause the extinction of flowers that were pollinated by birds. Other examples of functions that have been lost are the extinction of giant flightless birds such as the moas of New Zealand and the elephant birds of Madagascar that were probably acting like large terrestrial herbivores, as ungulates do in the continents.

How successful have bird introductions been throughout the world?

Introduced species are always related to human activities but can be intentional or accidental. For instance, “Acclimatization societies” encouraged the introduction of non-native species during the 19th and 20th centuries. The purpose of these associations, born when Europeans were establishing many colonies around the world, was to make some regions more familiar to Europeans, by releasing animals and plants from Europe elsewhere. The success of introductions can depend on different factors related to the introduction event, such as how many birds have been released, but also on the species' characteristics. Some traits can make species more prone to establish when introduced, such as having a relatively larger brain or reproducing multiple times each year.

Your study found that introduced species are not replacing the roles of extinct species. Can you please explain this further?

Some of the extinct species had a role in the ecosystem that have not been replaced by other birds. For example, some giant flightless species, like the moas of New Zealand and the elephant birds of Madagascar, were probably acting like large terrestrial herbivores, as ungulates do in the continents, but unfortunately were driven extinct by humans.

Why is it the case that larger birds and flightless birds are more likely to go extinct and what ecological effect does this have on the world?

Flightless birds are more prone to extinction as they have generally evolved in ecosystems with no predation. Therefore, when humans or invasive species arrive, they are not adapted to escape. In the case of body size, larger species are more prone to extinction for several reasons: First, they are easier to find, and they would be a rewarded target for hunting. In addition, they reproduce more slowly, taking longer to recover from population declines.

What do you feel must be done to reduce the number of birds being driven to extinction worldwide?

We should try to reduce habitat destruction (i.e., deforestation) in many tropical areas, where we have biodiversity hotspots. We also need to stop the introduction of invasive species in ecosystems, as they are also a main cause of extinction.

Do you have any further research that you are able to discuss?

In a previous study, we found that flightless species have been particularly prone to human-caused extinctions. Among extant species, only 0.5% of them are flightless (including iconic species such as ostriches and penguins). However, among extinct birds, almost 30% were flightless, including the famous Dodo from Mauritius, but also many other strange creatures such as flightless ducks in Hawaii or flightless owls in Cuba.

Where can readers find more information?

Current study (Functional loss):

Previous study (Flightless birds):

Video/Interview about flightless birds:


About Ferran Sayol

My research aims to understand how biodiversity has been originated and how it can be lost by anthropogenic impacts. I use a macroevolutionary approach, mainly using birds as a study model.

I did my Ph.D. in Barcelona (UAB, 2018), where I focused on the evolution of brain size in birds. Then, I conducted a postdoc at the University of Gothenburg, where I developed a project on global patterns of bird extinctions, aiming to understand how trait distributions are affected by non-random extinctions. Currently, I am a Marie-Curie Postdoc fellow at University College London, now focusing on the evolution of ecological niches and functional roles of birds.

Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.

Laura Thomson

Written by

Laura Thomson

Laura Thomson graduated from Manchester Metropolitan University with an English and Sociology degree. During her studies, Laura worked as a Proofreader and went on to do this full-time until moving on to work as a Website Editor for a leading analytics and media company. In her spare time, Laura enjoys reading a range of books and writing historical fiction. She also loves to see new places in the world and spends many weekends walking with her Cocker Spaniel Millie.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Thomson, Laura. (2021, December 14). Introduced Bird Species are Failing to Replace Extinct Bird Roles. AZoCleantech. Retrieved on May 27, 2024 from

  • MLA

    Thomson, Laura. "Introduced Bird Species are Failing to Replace Extinct Bird Roles". AZoCleantech. 27 May 2024. <>.

  • Chicago

    Thomson, Laura. "Introduced Bird Species are Failing to Replace Extinct Bird Roles". AZoCleantech. (accessed May 27, 2024).

  • Harvard

    Thomson, Laura. 2021. Introduced Bird Species are Failing to Replace Extinct Bird Roles. AZoCleantech, viewed 27 May 2024,

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Your comment type

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.