A new study researchers from the Australian National University (ANU) are pulling back the curtain on half a century of evidence detailing the impact of climate change on more than 60 different bird species.
It found that half of all changes to key physical and behavioral characteristics of birds since the 1960s can be linked to climate change.
The remaining 50% is due to other unknown environmental factors that have changed along with our climate.
The research, published in the Proceedings of the National Academy of Sciences and carried out in collaboration with James Cook University (JCU), focused on birds in the UK and the Netherlands.
“We have shown that climate change is a major driver of these changes in birds, but there is more at play here than we originally thought,” said lead author Dr Nina McLean, from the ANU Research School of Biology.
“Not only were other unknown changes in the environment equally important in driving changes in birds, but surprisingly they generally did so in the same direction as climate change, so their effects compounded. .
“This study shows that the impact of climate change does not act in isolation and that its effects are occurring in a world where the resilience of wildlife is already stretched to its limits due to the many other challenges they face in a landscape. male dominated.
“These non-climate change drivers could include urbanization, land use change, habitat loss, or the introduction of invasive species into ecosystems, but we cannot yet know their identity with certainty.”
The researchers analyzed three key traits in their study: timing of laying, body condition of the birds, and number of offspring produced. All data was collected by volunteers, otherwise known as citizen scientists.
The study found that, overall, almost all birds laid their eggs earlier due to climate change.
“For example, climate change has caused chicks to lay their eggs six days earlier for the past 50 years, but other unknown environmental factors have caused six extra days, which means that in total they are now laying their eggs 12 days earlier than they did half a century ago,” said Dr Martijn van de Pol, from the JCU College of Science and Engineering.
Dr McLean said there were “winners and losers” from these environmental changes driven by rising temperatures.
“For offspring count and fitness, we see it’s a mixed bag,” she said.
“Some species are clearly increasing their body condition and number of offspring, while others suffer.
“For example, garden warblers in the UK have seen a 26% decline in their average number of offspring over the last half-century, which is really concerning for the long-term fate of this species, but only half of this reduction, 13 percent, can be attributed to climate change.
“By comparison, the redstart has seen a 27% increase in the number of offspring over the past half-century, but again, only part of this increase is due to global warming.”
Researchers say continued global warming could present a “double whammy” for species that are already struggling to adapt to other non-climate environmental changes.
“Rising temperatures, compounded by these unknown environmental factors, could pose a significant threat to the livelihoods of some species that are already suffering,” said study co-author Dr Loeske Kruuk, also from the ‘ANU.
This study also involved researchers from the University of Edinburgh, the British Trust for Ornithology, the Sovon Dutch Center for Field Ornithology and the Dutch Center for Avian Migration and Demography.