A new study suggests a rising global temperature has reduced the birth rate of most birds across the planet, although some smaller birds appear to benefit from climate change.
Dr. Martijn van de Pol and Lyanne Brouwer, both researchers at James Cook University's College of Science and Engineering, took part in the study.
"Global temperature has increased 1°C during the past 50 years. Previous studies have shown how changes in temperature altered the timing of when birds breed. We systematically examined what this change means for the number of offspring produced," said Dr van de Pol.
The global team of scientists, led by Dr Lucyna Halupka from the University of Wroclaw, examined breeding data for 201 populations of 104 bird species from around the world between 1970 to 2019.
"More than 56% of bird populations in the study showed a decline in offspring production while 44% showed a positive trend.
"A decline was most common in migratory and large birds. However, other birds like small non-migratory species seem to benefit from global warming," said Dr Brouwer.
"Large species may be slower in responding to changing climatic conditions due to fact that they are long-lived, take several years to start breeding and produce small broods.
"Non-migratory species, especially smaller ones, are usually better able to adjust to changes in local conditions and may benefit from climate warming," said Dr Brouwer.
The researchers said declining birth rates could not fully explain why the vast majority of the bird species studied are declining in numbers, suggesting other causes for declines in avian biodiversity are also in play.
