Species aren't adapting fast enough to climate change

Climate change is outpacing the ability of birds and other species to adapt to their changing environment, according to an international team of 64 scientists.

Climate change can threaten species and extinctions can impact ecosystem health. It is therefore of vital importance to assess to which degree animals can respond to changing environmental conditions — for example, by shifting the timing of breeding — and whether these shifts enable the persistence of populations in the long run.

To answer these questions, researchers led by Viktoriia Radchuk, Alexandre Courtiol and Stephanie Kramer-Schadt from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) evaluated more than 10,000 published scientific studies to relate changes in climate over the years to possible changes in traits possessed by various species, including birds, turtles and some mammals. The team then evaluated whether observed trait changes were associated with desired outcomes, such as higher survival rates or increased number of offspring.

They found that species respond to climate change by shifting the timing of important biological processes, such as hibernation, reproduction and migration. The study found those changes, known as phenological traits, occurred more commonly in temperate regions, where biological processes were shifted to earlier dates than in the past. Species also can experience changes in morphological traits, such as body size and mass, but the study found no systematic pattern to explain how climate change affects these traits.

“We demonstrate that in temperate regions, the rising temperatures are associated with the shift of the timing of biological events to earlier dates,” Radchuk said. Co-author Steven Beissinger, Professor at the University of California, Berkeley, added, “This suggests that species could stay in their warming habitat, as long as they change fast enough to cope with climate change.”

However, the researchers also compared the rate of climate change responses observed in the scientific literature with a rate modelled to reflect how traits would have to shift to track climate change precisely. As outlined by senior author Alexandre Courtiol, from Leibniz-IZW, “Even populations undergoing adaptive change do so at a pace that does not guarantee their persistence.”

Even more worrisome for the researchers is the fact that the data analysed included predominantly common and abundant species such as the great tit (Parus major), the European pied flycatcher (Ficedula hypoleuca) and the common magpie (Pica pica), which are known to cope with climate change relatively well.

“Adaptive responses among rare or endangered species remain to be analysed,” said Stephanie Kramer-Schadt, Head of the Department of Ecological Dynamics, Leibniz-IZW. “We fear that the forecasts of population persistence for such species of conservation concern will be even more pessimistic.”

Fredric Janzen, from Iowa State University, added that long-lived species such as painted turtles may seem like they are successfully adapting to altered environmental conditions brought on by climate change, when this isn’t necessarily the case. He speculated that climate change may cause breeding declines in turtle populations that could threaten their existence years hence, saying, “It’s possible we’ll have populations that will be functionally extinct but won’t be able to produce sufficient offspring to replenish themselves in the long term.”

The scientists hope that their analysis and the assembled datasets, published in the journal Science Communications, will stimulate research on the resilience of animal populations in the face of global change and contribute to a better predictive framework to assist future conservation management actions.

Image caption: The study focused on abundant bird species such as the great tit (Parus major), which are known to have developed adaptations to climate change. Image ©Bernard Castelein.

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