New Delhi, Aug 11 (PTI) Heat extremes driven by climate change may have reduced the world's tropical bird population by 25-38 per cent on average since 1950, a study has estimated.
Findings published in the journal Nature Ecology and Evolution suggest that climate change is endangering tropical bird populations even in the absence of direct human pressures, such as changes in land use, researchers said.
The world's tropical regions -- having a high biodiversity -- are home to nearly half of all bird species. However, many species are said to be living at temperatures close to their tolerance thresholds.
The team, led by researchers at Spain's Barcelona Supercomputing Centre and Potsdam Institute for Climate Impact Research in Germany, said that impact of heatwaves on birds, including tropical populations, remains under-studied.
They analysed data gathered from monitoring over 3,000 bird populations across the world during 1950-2020, resulting in over 90,000 observations.
Compared to a scenario where there is no human-caused climate change, "the historical intensification of heat extremes has caused a 25-38 per cent reduction in the level of abundance of tropical birds, which has accumulated from 1950 to 2020," the authors said.
An exposure to extreme heat -- defined as days registering temperatures among the highest one per cent for a region -- was strongly related with a reduced growth in yearly bird numbers, especially in tropical regions.
The researchers said that the analysed impacts of heatwaves were consistent across modelling approaches and migratory behaviours of the bird species.
They added that the total impact of human-caused intensification of heat extremes over the decades was more than that from direct human pressures in the studied tropical populations.
The study highlights the growing threat of climate change, with heat extremes playing a critical role in endangering bird numbers in tropical regions.
Along with strategies to mitigate greenhouse gas emissions, the authors also called for conservation measures addressing both habitat protection and the growing threat of climate extremes.