A new study published in Science reveals that the extinction of hundreds of bird species by humans over the past 130,000 years has resulted in significant reductions in avian functional diversity. This measure reflects the range of roles and functions that birds perform within their environment. The loss of these species has also led to the disappearance of approximately 3 billion years of unique evolutionary history. The research, led by the University of Birmingham, underscores the severe consequences of the ongoing biodiversity crisis and emphasizes the urgent need to identify the ecological functions that are being lost through extinction.
The study highlights the impact of human-driven extinctions on avian biodiversity, focusing on the wider implications beyond just the number of extinctions. Scientists have evidence of at least 600 bird species that have become extinct as a result of human activities since the Late Pleistocene. These extinctions have had significant repercussions on the planet, affecting important ecological roles performed by birds such as controlling pests, recycling dead matter, pollination, and seed dispersal. When these species become extinct, the functional diversity they provide also disappears, disrupting ecosystems and the services they provide.
Lead author Dr. Tom Matthews explains that each bird species carries a certain amount of evolutionary history, and when they become extinct, it is akin to cutting off a branch of the tree of life. This loss of phylogenetic diversity further exacerbates the impact of extinctions on the environment. The research found that the scale of anthropogenic bird extinctions has resulted in the loss of approximately 3 billion years of unique evolutionary history and 7% of global avian functional diversity. These losses are larger than expected based solely on the number of extinctions, indicating the far-reaching implications of these extinctions on ecosystem functions.
The consequences of avian extinctions extend beyond just the loss of species diversity. The reduction in avian functional diversity has disrupted important ecological processes such as flower pollination, seed dispersal, and top-down control of insect populations. This disruption can lead to increased pest populations, disease outbreaks, and challenges for plant species to adapt to climate change. The downsizing of the global avifauna documented in the research is likely to have significant impacts on ecosystem dynamics and the ability of species to adapt to changing environments.
Dr. Matthews emphasizes the importance of understanding and predicting the impacts of past anthropogenic extinctions on ecosystem function to prepare for future losses. With an estimated 1,000 bird species projected to become extinct over the next two centuries, it is crucial to take action to mitigate the potential consequences. This information is essential for informing global conservation strategies, ecosystem restoration efforts, and rewilding initiatives. By recognizing the impacts of human-driven extinctions on avian functional and phylogenetic diversity, researchers can work towards setting effective targets for conservation and restoration to preserve the complex web of life on Earth.
