A new research has claimed that climate change is an important emerging driver of change in bird communities and a particular concern for tropical montane, polar, and migratory species.
Global bird populations have steadily declined for the last three decades. The continued growth of human footprint on the natural world, which has led to the degradation and loss of natural habitats, and the direct overexploitation of many species are the key threats to avian biodiversity, says research titled ‘State of the World’s Birds’ published in Annual Review of Environment and Resources on May 5.
“Approximately 48 per cent of extant bird species worldwide (5,245) are known or suspected (based on inference from trends in habitat extent/condition and incomplete or anecdotal information) to be undergoing population declines, compared with 39 per cent (4,295) with stable trends, 6 per cent (676) showing increasing populations trends, and 7 per cent (778) with unknown trends. Habitat loss resulting from land-use change typically occurs concurrently with habitat fragmentation and habitat degradation, which interact synergistically to drive changes in avian community composition,” the research stated.
The study, which involved scientists from Manchester Metropolitan, Cornell University, Birdlife International, University of Johannesburg, Pontifical Xavierian University and Mysuru-based Nature Conservation Foundation, India, reviewed changes in avian biodiversity using data from the International Union for Conservation of Nature’s Red List to reveal the changes in fortunes of the globe’s 11,000 bird species.
The findings state that human infrastructure and artificial light at night (ALAN, a form of pollution), often associated with buildings, impact the ability of migrating birds to access cues for navigation and orientation and act as a major sublethal impact to birds.
“Globally, there has been a deterioration in the conservation status of the majority of bird populations, including that of many formerly abundant species, especially at temperate latitudes. Threatened species are concentrated in the tropics, which host the richest avian diversity. The most significant threats to avian biodiversity are habitat loss, fragmentation, and degradation coupled with human overexploitation and invasive alien species,” the research stated.
Dr Alexander Lees, senior lecturer at Manchester Metropolitan University and lead author of the study, said: “Avian diversity peaks globally in the tropics and it is there that we also find the highest richness of threatened species. We know a lot less about the fortunes of tropical bird species than we do about temperate ones, but we are now witnessing the first signs of a new wave of extinctions of continentally-distributed bird species which has followed the historic loss of species on islands like the Dodo.”
Dr Ken Rosenberg, a conservation biologist at the Cornell Lab of Ornithology, Cornell University, added: “After documenting the loss of nearly 3 billion birds in North America alone, it was dismaying to see the same patterns of population declines and extinction occurring globally. Because birds are highly visible and sensitive indicators of environmental health, we know their loss signals a much wider loss of biodiversity and threats to human health and well-being.”
Alongside tropical forests, natural grasslands emerge as a habitat which is particularly threatened, with strong declines in grassland birds observed in North America, Europe and India.
Dr Ashwin Viswanathan, a researcher at the Nature Conservation Foundation, India, said: “If unique ecosystems like grasslands are to retain their diverse birdlife into the future, both Governments and research groups must prioritise such landscapes and their inhabitants for conservation and ensure that they do not become plantations or woodlands. To save our birds and their habitats, facilitating easy, focused and extensive research of threatened species is key. The more we understand about these birds, the better our chance of saving them.”
Dr Stuart Butchart, chief scientist at BirdLife International, said: “The world’s birds are in trouble, with their populations being rapidly reduced by a range of different threats. This is alarming, because of the key role they play in ecosystems and their trends signal broader environmental losses. It is not too late to save our natural heritage but substantial action is urgently needed. The world’s birds point the way to the steps required for a nature-positive future.”