Bird populations in the tropics have dropped by roughly 25 to 38 per cent since 1980 due to intensifying heat extremes linked to climate change, with some species declining by more than 50 per cent, according to a new study.

The research, published on Monday in the journal `Nature`, involved scientists from the Potsdam Institute for Climate Impact Research (PIK), the University of Queensland and the Barcelona Supercomputing Centre (BSC).

"It`s a staggering decrease. Birds are particularly sensitive to dehydration and heat stress. Extreme heat drives excess mortality, reduced fertility, changing breeding behaviours and reduced offspring survival," said lead author Maximilian Kotz, a guest researcher at PIK and researcher at BSC.