A new study by researchers from The Australian National University, (ANU), sheds light on the half century of evidence detailing climate change’s impact on more than 60 species of birds.
It was discovered that climate change is responsible for half of all changes in key bird characteristics and physical traits since the 1960s.
The remaining 50 percent is due to unknown environmental factors that have also changed simultaneously with our climate.
The research was published in Proceedings of the National Academy of Sciences This research was done in collaboration with James Cook University (JCU) and focused on birds in the United Kingdom & the Netherlands.
“We have shown that climate changes are a major driver of these changes for birds, but there’s more at work here than we initially thought,” said Dr Nina McLean, lead author from the ANU Research School of Biology.
“Not only were other unknown environmental changes equally important in driving changes for birds, but they also did so in the same direction that climate change, so that their effects compounded.
“This study shows climate change is not an isolated phenomenon. Its effects are already being felt in a world where wildlife’s resilience is already at its limits due to other challenges they face in a human-dominated environment.
“These non-climate-change driven factors could include urbanisation and changing land use, habitat loss, and introducing invasive species to ecosystems. But, we don’t know their identity yet.”
As part of their study, the researchers looked at three key traits: the timing and body condition of the birds as well as the number of offspring. The data was collected by volunteers, also known as citizen scientists.
The study revealed that almost all birds lay their eggs earlier due to climate change.
Dr Martijn van der Pol from the JCU College of Science and Engineering stated that climate change had caused chiffchaffs’ eggs to be laid six days earlier in the last 50 years. However, other unknown environmental factors resulted in an additional six days. This means that they now lay their eggs twelve days earlier than they did half-a century ago.
Dr McLean stated that there are both winners and losers in these environmental changes caused by rising temperatures.
She stated, “For offspring numbers and body condition, we see that it is a mixed bag.”
“Some species are clearly improving their body condition and offspring numbers, whereas others are suffering.
“For instance, in the UK, garden warblers have experienced a 26% decline in their average number offspring over the past 50 years, which is worrying for the long-term fate. But only half of this decrease, 13%, can be attributed climate change.
“By comparison, redstarts have seen a 27% increase in their offspring numbers over half a century, but again, only a small portion of that increase can be attributed to global warming.”
According to the researchers, continued global warming could lead to a “double whammy,” for species that already struggle to adapt to other nonclimatic environmental changes.
Dr Loeske Kruuk, a co-author of the study, stated that rising temperatures and unknown environmental factors could be a threat to certain species already suffering.
This study also included researchers from the University of Edinburgh and the Sovon Dutch Centre for Field Ornithology and Sovon British Trust for Ornithology.
