Global warming is leading to a decline in the number of nestlings of migrating birds and large birds, according to a new international study that included the University of Haifa and the Shamir Research Institute in Katzrin. Conversely, the study found an increase in the number of nestlings among smaller, non-migrating birds.
“The concern is that if the downward trend in the number of baby birds unable to leave their nests continues, this will impact the ability of the large and migrating bird species to survive in the long term. These birds play an important role in maintaining the global ecosystem,”
Dr. Motti Charter
“The concern is that if the downward trend in the number of baby birds unable to leave their nests continues, this will impact the ability of the large and migrating bird species to survive in the long term. These birds play an important role in maintaining the global ecosystem,” explained Dr. Motti Charter of the University of Haifa and the Golan Heights Institute, which has been operating for over 30 years to advance the practical, applicable and academic research in a varied gamut of subjects.
The study has just been published in the prestigious journal PNAS under the title “The effect of climate change on avian offspring production: A global meta-analysis.” Edited by Nils Stenseth of the University of Oslo, Norway, it included a few dozen ornithologists and other experts around the world from Poland and Mexico to the US and Portugal.
How has climate change impacted birds?
Numerous studies have shown that climate change has altered avian timing of breeding and its impact on birds’ reproduction and migration habits, but little is known about climate-driven changes in offspring production.
In the current study, the large team of researchers set out to examine the impact of global warming on the reproduction of birds and specifically the number of nestlings they produce. To study and identify a connection between climate changes and alterations in the number of birds, the researchers used data collected from specific species around the globe over 15 years.
“The number of researchers worldwide who have long-term monitoring data of a specific species is fairly small, making this study unique,” Charter commented. The team collected information on 201 breeding populations from 104 species of birds from every continent and a total of 745,962 nests. They included data from the breeding seasons in 1970 to 2019, including daily temperatures, the number of eggs, nestlings per pair and the number of nests for each population.
Global temperatures have been rising significantly during the 20th and 21st centuries, they wrote. Higher temperatures and changes in precipitation patterns have resulted in shifts of climatic zones, altering the conditions that animals experience in their breeding grounds, their wintering grounds and during migration.
The study results showed that global warming decreased the number of nestlings produced in 57% of the species. Conversely, in 43% of the species, an increase was seen. Charter noted that the data reflect the complex impact of climate change and global warming.
More specifically, the findings showed that large and migrating birds’ reproduction decreased, whereas smaller, non-migrating, resident birds increased the number of nestlings they produced. “Smaller bird species may have a preference for warmer weather, and they may also be able to adapt more rapidly to changing temperatures.”
They found that large and migrating birds are producing less young. In addition, these birds play an essential ecological role in areas such as the dissemination of nutrients, pest control, maintaining biological balance and more, so damage to these species may be significant.
Furthermore, if global warming continues, the decrease in the number of nestlings produced by migrating and large birds potentially can push sensitive species to extinction, thereby greatly damaging the ecosystem,” Charter warned.
The authors suggested that future studies should identify the reasons for nest failures to understand better the factors underlying declines in offspring production in avian populations.
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